Pauldos Personal Laser Blog

Laser Blog

Pauldos!

Laser Blog

More solutions for laser levels
Posted by Pauldos! on 18/04/2010

I have been a bit surprised by the response to this blog. I wasn't even sure anyone has been reading it. But the hit counter down there shows that hundreds of visitors have read this column, and I have been getting a hell of a lot of emails from readers hungry for more information on repairing laser levels. So therefore I have begun compiling information on repairing laser levels, and I will be opening a whole new website to present them. Once it is open, this little blog will be closed down.

The new website won't be free for everyone, as it is taking me some time and effort to compile all the repair techniques I have developed over the last few years.

I am hoping to make it a community site, where all members contribute repair information, so I will be offering it for free to those who can contribute. If these techniques can help us to do more repairs in-house, our customers will be happier, and we will be wealthier.

Obviously it will be aimed at technicians in the laser repair industry, as a certain level of skill will be required to carry out most of these repairs. But as a lot of the repair techniques I have developed are in my head, it will take some time to generate pictures, schematic diagrams, and write up procedures. I hope to open the site by the end of May.

The website has been created, and the upload of information has begun. It has not been submitted to the search engines yet, so don't bother searching for it.

I will update this entry with the URL as soon as it is ready. Stay tuned !!

Coming Soon...

On 25/11/2011, Ton had this to add -Dear Pauldos! I'm offered a broken Topcon RL-20. Since you seem to have quite a lot experience on laser equipment repairs, you might be willing to give me some advise. Can you make an educated guess on what's causing the laser beam malfunction? Do laser diodes(?) wear-out? If yes, are replacement diodes only available through Topcon, or are this standard part that you can buy somewhere? Have you reversed engineered the Topcon 20 electronics? I have qute some electronics knowledge, and suffiecient equipment to carry out repairs like this. What missing is specific know how on laser devices. I would be very gratefull if you would contact me on fuerteventurafunAThotmail. Thanks in advance, Ton. PS where are you living?? I live in the Netherlands.

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1271564216

Leica Rugby 100 Levelling Problems
Posted by Pauldos! on 12/09/2009

I have had a number of Leica Rugby 100 lasers presented to me with the complaint that the laser either does not self-level, or is out of it's calibration range. The regular solution is to return these lasers to the manufacturer, who will replace the levelling block or the entire upper optics assembly. This is an expensive solution that the customer may be unwilling or unable to pay for, which often results in the customer abandoning the laser and either buying a cheap laser or going without a laser entirely.

In this article, I will present a solution that will take a couple of hours of work, and provide a reasonable cost solution for your customer, and provide income that you would not get if the customer abandoned the repair.

The fault, either not levelling or out of calibration range, usually presents after a fall or similar heavy shock to the laser. In the case of not levelling in one or both axes, one or both of the levelling vials in the levelling block are broken. In the case of the laser being out of calibration range, one or both of the levelling vials in the levelling block have moved out of position. Most of this procedure covers both faults. You'll get the idea.

As always with working on lasers, perform this procedure in a clean work area, with clean hands and tools. The internal optics will be exposed during this procedure, so take care not to touch or damage the optics. If you cannot complete this procedure in a single sitting, cover the optics while not being worked on.

Remove the battery. Disassemble the laser. Remove the upper optics assembly by removing the three screws.

Loosen the two screws on the levelling block lever arms. Pull out the lever arm pins.

Removing lever arm pins

Turn the upper optics assembly over and remove the spring. Remove the three screws securing the levelling block to the upper optics assy. Remove the levelling block. The laser diode focusing lens will now be exposed. The coating on the lens is delicate and it should not be touched.

Removing the levelling block

Remove the level-sensor PCB by removing the three retaining screws and lifting the PCB straight upwards. If you have a broken level vial, it should now be obvious.

Removing the level-sense PCB

The exposed level vials, undamaged in this instance

Each level vial is held in place by a spring steel retainer. The fingers of the retainer are glued to the level vial, so you will have to cut under the finger with a scalpel or sharp thin-bladed knife. Cut in small slices until the finger is released from the vial. If you try to cut the finger away in one slice, or try to break the finger away from the vial, it is likely that the vial will shatter. If the vial is already broken, this is not much of a concern.

The levelling block has been manufactured with holes at each end of each level vial cavity, tapped M2.5. I suspect that these holes are used to set the position of the level vial during manufacture. We will use them to make the vial position adjustable. I obtained a couple of springs from the Seal and Bearing shop around the corner. I fitted an M2.5 x 16 screw to the end of each vial cavity, and fitted the spring so that it pushed on the other end of the vial (see picture below). If you are using the existing level vials, glue a small piece of rubber to the end of the vial so the the end of the screw does not damage the end of the vial. Put the spring retainer back in, but don't glue it to the level vial, or at least don't glue it to the vial until you have calibrated the vials.

The laser featured here had two smashed level vials, so I had to replace them both. (the picture above is from another Rugby 100 which was out of calibration range, also repaired with this procedure) It took me some time to find suitable level vials suitable for this laser. The main concerns about the level vials are the size of the vial and the size of the bubble in the vial. If the level vial is too large or too small, it won't fit in the vial cavity properly. If the bubble in the vial is too small, the laser will 'hunt' for level. If the bubble in the vial is too large, the levelling deadband will be too large, and the laser will find arbitrary level.

The level vials out of a Bear TL-18 laser spirit level proved to be ideal. Many thanks to Doug from Cody Corporation for providing the TL-18 for this article. The level vials were fitted with the screws and springs as mentioned above.

Once the level vials are fitted, or refitted, reassemble the laser. With the housing removed, set the laser up on your calibration range. Allow the laser to find level. Adjust the M2.5 screws until laser is calibrated, allowing time for the laser to re-adjust to level after each movement of the screws. This will be tedious and slow, and you probably won't be able to get the laser perfectly calibrated by these adjustments. You just need to get it close, and do a regular calibration procedure after. Once the laser is calibrated, put a small drop of glue on the threads of the M2.5 screws to prevent movement.

The laser featured here was tested extensively over the next two weeks, and there was no evidence of hunting or arbitrary levelling. It was then placed in the hire fleet, and it's calibration checked before and after each hire. There was no loss of calibration. And as anyone who hires out equipment can tell you, there is no better test of the ruggedness of an instrument than hiring it out. The featured laser was recently sold to a customer who will regularly bring it in for checking, but I don't anticipate any problems. As at the writing of this article, two Rugby 100's have been repaired this way, one with broken vials, and another that was out of calibration range.

The replacement level vials with springs and adjuster screws.

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1252729875

Thermal Stability Tests of Green Laser Levels
Posted by Pauldos! on 01/08/2008

Within the company I work for, we have two departments. Building and Construction Lasers, and Industrial Lasers. I am in the Industrial Lasers department, manufacturing our own brand of industrial lasers and servicing/maintenance of other brands of industrial lasers. Obviously, I also provide technical support to our B&C lasers department. Recently one of the staff of the B&C department approached me with a problem.

We have been selling, apparently, green beam levelling lasers. I'm not a fan of the green beam laser, professionally. They're OK as toys. The problem is that Diode-Pumped, Solid-State, Frequency-Doubled (DPSSFD) lasers are not temperature stable. Excellent laser-man, Sam, has some details about DPSSFD lasers and why they are unstable. Read his explanation here

. Wikipedia has a concise description of the construction of DPSSFD lasers here

. DPSSFD lasers can be stabilised with the use of a Thermo-Electric Cooler (TEC), but TEC's require a lot of power, so temperature stabilisation using a TEC is pretty much ruled out in battery-powered applications.

The problem that the B&C staff had was with the CST/Berger model ALHV-G. All of the few units that we had acquired had powered up with no beam in the morning. One unit that had been sold to a customer had come back the very next day. The customer that purchased it was not amused that it did not have a beam when he went to use it on it's first day on the job. These lasers were returned to the supplier, but the B&C staff had concerns about the model, and asked me to test the replacement lasers before they were put back on the shelves. The manufacturer's stated operating temperature range is 0 degrees to +40 degrees.

I buried a precision temperature sensor at the top of the tripod mount and packed it with foam-rubber. The cast aluminium chassis, and surrounding battery pack provided sufficient thermal mass to get a close enough reading of the temperature of the laser diode. The laser was then placed in the lunch-room refrigerator overnight. The staff have seen many scientific experiments conducted in the fridge over the years, so no-one asked. By the way, the lunch-room fridge frequently contains beer on Fridays, and the beer-drinkers claim that the fridge temperature is 'about two degrees'. These experiments confirmed that the fridge temperature is 1.71 degrees. The laser was removed from the fridge in the morning and setup on the bench. Conveniently, these lasers can have the rotation stopped, so the beam was aimed into the power meter's sensor head about 100mm away. I monitored the laser as the temperature slowly rose to ambient, and recorded the output power at half-degree intervals. Once the laser reached ambient, I switched on an overhead heat lamp to bring the laser up to higher temperatures. At the low temperatures, I had to wipe the condensation from the lighthouse before taking the power reading.

The results were scary. This laser had no output at temperatures below 16 degrees. I will get another one or two on the test bench to confirm this, but anecdotal evidence from the B&C staff is already confirmed by these results. It has been uncharacteristically cold the past couple of weeks here in Queensland, which may be why this problem has cropped up, but I can't explain why this hasn't been seen in the southern states, where it is normally colder. Curious. My employer has suggested that maybe our suppliers have deliberately sent us the lasers that failed the 'cold day' tests, presumably thinking that the problem may escape notice in the warmer climate, but I don't believe that. Perhaps it has been uncharacteristically warm down south?

Following the test on the CST/Berger, I conducted the same test on a David White A3150-G, and on an MCE LAS.203.G, for comparison. More tests to follow.

The David White laser was remarkably stable for a DPSSFD laser. Average output power is around 1mW.

Temp -vs- Power of a David White A3150-G

The MCE laser humorously specified an operating temperature range of -20 degrees to +50 degrees.
Gotta make sure that snow is level...
But as we can see here, it is pretty much dead below 6 degrees.

Temp -vs- Power of an MCE LAS.203.G

Temp -vs- Power of another CST/Berger ALHV-G

I also tested a Laser Alignment 6790 green beam pipe-laying laser. The stability was so surprising that I called out to the workshop staff "Hey, this one's got a control circuit !!"

Temp -vs- Power of a Laser Alignment 6790

I recommend the MCE laser. It's cheap, it's reasonably stable down to 6 degrees, but more importantly, it has bags of power.

The B&C staff will supply me with more green beam lasers, including trying to 'borrow' a Topcon RL-VH4G, for testing. I will test these lasers over the coming weeks, production schedule permitting, and update this article with the test results as they become available.

Temp -vs- Power of a CST/Berger ALHV-G, the laser of main concern.

On 27/04/2010, nox had this to add -David White A1350-G?? or 3150-G

On 27/04/2010, Pauldos had this to add -Yes, you're right. Corrected. Thanks.

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1217596159

Pro-Shot L4 Laser Diode Current Control.
Posted by Pauldos! on 20/04/2008

An L4 came into the workshop recently with the customer complaint 'no beam after 5 minutes'. It was tested by one of the lower-order technicians, pronounced 'OK', and returned to the customer. When it bounced, that is, the customer brought it back again, it was brought to my work area for deeper scrutiny. When I read the complaint, my experience told me that this would be a temperature-related problem. I set the laser up in my temperature controlled workshop and let it run. It performed flawlessly for two hours. I then put it in the oven and brought the laser up to forty degrees, whereupon the fault presented itself. The beam faded away till there was no detectable output. Visual inspection showed nothing untoward about the circuitry, and the fact that it operated normally at room temperature indicated that the laser diode was not faulty. The laser diode output power was 0.9mW at 26 degrees. A little low for my liking, but I have noticed that L4's, and indeed many makes and models of laser, have a widely varying output power from one unit to the next. OK, time to get serious.

First of all, let's find out what part of the laser is temperature sensitive. With a mini heatgun, I heated up various areas of the PCB, with no effect. When I heated up the laser diode housing, the power plummeted precipitously. This is not unusual. Laser diodes are affected by temperature and in fact many 'current-control-mode' laser diode power supply circuits incorporate a thermistor to compensate for temperature variations. So, back to the PCB. Checking the laser power adjustment, I discovered that it was already at maximum. Could the L4 be a current-control circuit? The laser diodes has a monitor photodiode, so why wouldn't the manufacturer use it? The monitor of the laser diode definitely seems to be a part of the diode control circuit. I'm going to need a circuit diagram to get to the bottom of this.

I reversed-engineered the laser diode control. The diagram is presented below. Q3 is controlled by the microprocessor, to power up the laser diode circuit when the compensator is in range. I don't know what the hell Q7 is doing, perhaps a future input point for modulation? Anyway. The laser diode runs from the 3V3 rail. The forward voltage drop measured across the laser diode at 80mA was 2.45V. That doesn't leave much overhead for the regulator circuit, so I think I already know what the problem is going to be. Looking up the datasheets for Q2 and Q3, I found that there was no stated 'minimum' or 'typical' collector-emitter saturation voltage for either transistor, only a 'maximum' of 0.5V for the MPS6521 and 0.4V for the 2N4401. I measured the voltage across the collector-emitter junction of both transistors and Q2 was 0.2V, and Q3 was 0.16V, which must be close to minimum Vsat for both transistors. I halved the value of R13 by tacking a 5R6 resistor across it. The laser diode current did not change, but the voltage across R13 went down, and the voltage across Q2c-e went up. AH-HAH, so Q2 is not getting enough drive to it's base. Looking at Q1, R12 is jumpered with a 1K1 resistor, and VR1 is screwed all the way clockwise so that it is zero ohms, so there is nothing to play with there. R10 is already a low value at 562 ohms, so that only leaves Q2's bleed resistor, R11. I changed R11 to 10K, and with R13 at 2R8 ohms, the circuit came into regulation. I was able to adjust the laser diode power up to 1.2mW, and the power was stable with a laser diode temperature up to 50 degrees. VR1 was still near the end of it's travel, but at least I had regulation. I would have liked to have got 1.5mW, but 1.2mW is acceptable for this laser. Removing R11 entirely would probably give me the control that I want, but that experiment will have to wait for the next time.

So it appears that the reason I have been getting varying power readings for these lasers is that the laser diode control circuit is barely in regulation, if at all. This, and the fact that R12 is jumpered, indicates that this circuit was designed for a different laser diode. Poor design is the main cause of this fault.
The laser was returned to the customer and he is now as happy as a pig in shit.

On a final note, we can now see the failure mode caused by C8 from the previous L4 article. With C8 reverse-polarised, it would have been forcing current into the collector of Q3, causing Vc-e to rise, and cutting off drive to the laser diode.

Partial schematic of the L4 - laser diode control.

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1208681798

In the unlikely event...
Posted by Pauldos! on 22/11/2007

A long time ago I was told that when someone utters the words 'In the unlikely event...', that event was doomed to transpire.

I got a call from a researcher at an Australian university a while ago, complaining that her gas chromatography / mass spectrometer was playing up. 'What the hell is that?' I asked. It seems that the nitrogen laser was firing spontaneously. I said that I would take a look at it. When the laser unit, a Thermo Laser Science VSL-337ND-S, arrived in my workshop, I set it up and let it idle. Sure enough, the laser would pulse every now and then with no trigger signal present. I have to admit I spent a little time playing with it, observing how different materials fluoresced in the UV light.
I reverse-engineered the trigger circuit and analysed it from top to bottom. I could see no noise that would cause false triggering of the laser. I grounded the trigger input right at the laser head, but the spontaneous triggering continued. I took the cover off the bronze-coloured aluminium case of the laser head, but the interior of the housing was completely potted. Nothing to see here.
The laser head was powered from a high-voltage power supply (I don't remember the voltage) so I assume it must be either flashlamp pumped, or direct cavity discharge pumped. I turned to the owner's manual. In the troubleshooting section, there was a reference to spontaneous triggering. The manual directed the operator to check the trigger input, because a spontaneous trigger without input was 'highly unlikely'. Well there we have it. The manual said the magic words, so therefore it must be self-triggering. Well if the cavity or flashlamp were spontaneously discharging, it seems logical that the voltage could be too high. I checked the HV power supply, and it did have an adjustment. I lowered the HV by one percent. The spontaneous discharges ceased. I lowered the voltage another one percent, just to be sure, and gave the laser rigorous tests with both internal and external triggering. It performed flawlessly, so I shipped it back to the customer. She was very happy, and sent down the laser out of the other GC/MS machine, which had the same problem. I corrected it with the same procedure. She tells me that the lasers have been performing to specifications ever since.

This is a picture that I pilfered from Google images, as I didn't take a picture of the units I repaired.

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1195733486

A Pro-Shot L4 with a dead diode, or so I thought.
Posted by Pauldos! on 31/10/2007

An L4 levelling laser came in for repair with the complaint that 'it turns off after 5 minutes'. I set the laser up on the bench and turned it on. After about 5 minutes, the receiver was no longer responding to the laser. The laser did not turn off, the rotor was still running, but there was no beam. I disassembled it, connected a current meter and the laser power meter, and powered it back up again.

The laser output was steady at 1.5mW, as was the current at about 100mA. After about 5 minutes, the laser power dropped to 1.4mW, and the current jumped up to about 110mA. Over the next 30 seconds the current climbed slowly, with the laser output steady at 1.4mW, until it reached 280mA. There the current stopped rising and the laser diode output power began falling at about the same rate that the current was previously rising. Obviously there was some current limiting in play. I have seen this before, many times. The laser diode power control circuit, like most laser diode power control circuits, operates on a feedback principle. The circuit senses the laser diode's output power from the in-built sensor, and controls the current in the laser diode in order to control the output power of the laser diode. Of course as the laser diode ages, it takes more current to maintain the same power output. And when the laser diode has reached the end of it's life, the control circuit ramps the current up until it hits it's preset limit, if any, in a futile attempt to get the laser output power up to the required level. Low laser power and a high diode current are the hallmarks of a dead diode. So I ordered a new diode from our suppliers and fitted it. Guess what? I wouldn't be writing this article if the laser was all better now, would I? But was the new diode faulty? Was the circuit faulty and killing the new diode? I had fitted the diode at my static-safe workstation, and turned down the laser diode drive before powering up.

So, I had to find out for sure the status of the laser diode. I removed the laser diode from the laser, and fitted it to my test holder. I connected it to the power supply, sticky taped an aspherical lens to the front of it, and aimed it into the power meter. I brought the power supply up until the output power was 1.5mW, and kept an eye on the power and current for the next four hours. Rock steady. So, the control circuit was faulty, but at least it was faulty in a good way. I.E., it did not destroy the laser diode.

I contacted our supplier to see if they had any schematics of the control board, but they did not. They did, however, offer to sell me a new control board at exorbitant cost. I declined. So I decided to reverse-engineer the control board, a favourite past-time of mine. In fact I have quite a collection of circuit diagrams for lasers that circuit diagrams do not otherwise exist for. Before I started reverse-engineering the board, I thought I would take a quick visual inspection, just to see if there might be anything obvious that might lead me down the right path. Alas, no cracks, no dry joints, no burnt components. As I started my reverse-engineering, I mused to myself that the manufacturer had managed to design the board so that all the tantalum capacitors faced the same way except for one... wait a minute! Sure enough, C8 was in backwards. A manufacturing defect that had not shown until nearly a year after the laser was put in use. I replaced it with a new capacitor, fitted the original laser diode back in, and there was joy in the world again.

Testing the laser diode. The power meter shows 0.7mW because the aspheric lens fell off.

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1193808748

Are lasers really dangerous to aircraft pilots?
Posted by Pauldos! on 30/10/2007

There has been some hulla-balloo in the news recently about people shining lasers at aircraft. The police say that this has the potential to blind pilots, is highly dangerous, and could cause a plane crash. I have no doubt that final approach is a really bad time for such a distraction, but is there really any danger? And is proven to be deliberate? Let's look at the facts, and run the numbers. As the current-affairs shows that I have seen depicted both red and green laser pointers, I have analysed both and I will present the worst-case.

The lasers that would typically be used by these nasty-pilot-blinder persons are the commonly available low-cost laser pointers. In the red corner, you can get a 1 milli-watt (mW), 635 nano-metre (nm) for under $10 just about anywhere. Not as commonly available, but still easy to get is the red 3mW, 635nm or 650nm for under $20. In the green corner, you can get 10mW, 532nm for around $20 - $30. The green lasers are popular with the astronomy buffs. I have spoken to a number of these people, and they tell me that they use them to point out constellations to their colleages and students. Apparently the green laser shows up a very visible green line high up into the atmosphere. Some of them attatch the green lasers to their telespopes, so they can get rough alignment with their stars of interest before peering into the telescope. This could cause an inadvertent illumination of an aircraft. As the green lasers are available in a higher power than the red lasers, and the human eye is more responsive to green light than red, I will run these calculations based on a 10mW, 532nm green laser pointer.

So. lets start with some parameters. Firstly, I open my copy of Australian Standards AS-2211.1:1997, Laser Safety. This is a publication that I use frequently in my work with lasers. First of all, let's calculate what the safe level of laser energy really is.
The Maximum Permissible Exposure (MPE) for visible laser energy arriving at the cornea of the eye, with the pupil fully dilated, (iris wide open at night, pupil is 7mm diameter) is found with the formula :
MPE-h = 18 x t^0.75 x C6, for exposure durations up to 10 seconds.
where - MPE-h is in Joules-per-square-metre (Jm^2)
t = exposure duration, in seconds. (Let us assume that the pilot has the laser in his eyes for the full 10 seconds)
C6 is a correction factor for viewing angle.
(we will use 1 for C6, which is the correction factor for looking directly at the laser)
MPE-h = 18 x 5.6 x 1 = 101.2 Jm^2 or 101 Joules per square metre
Now let's convert this to watts per square metre (Wm^2), using the formula :
MPE-e = (MPE-h / t)
MPE-e = (101.2 / 10) = 10.12 Wm^2, for a duration of 10 seconds.
Now let's get the energy density in square millimetres (Wmm^2)
1,000,000 (number of square millimetres in a square metre)
10.12 / 1,000,000 = 0.00001012 Wmm2 or 10.12 micro-watts per-square-millimetre (uWmm^2)

OK, now lets find out what the energy density of our laser pointer is. We have a 532nm, 10mW green laser with an emergent beam diameter of 4mm, and a divergence angle (how much the beam spreads out over distance) of 1.5 milli-rad (mrad). 1.5mrad means that the beam spot gets 1.5mm bigger for every 1 metre from the laser. In fact, many of these lasers are outputting much less than 10mW, typically between 4mW and 8mW. And the divergence angle is usually between 1.6 and 3 mrad. But as this is a worst-case example, let's say our nasty-pilot-blinder person has picked out the laser with the absolute best specs, doing a full 10mW, and a divegence angle of 0.25mrad.

Energy density at the aperture is found by dividing the power output by the area of the beam spot at the aperture.
Area of a circle = pi x (r^2) = 3.14 x (2^2) = 12.6mm^2
10mW / 12.6mm^2 = 796uWmm^2
This is nearly 80 times the maximum safe level, instant blindness if you shine it directly into your eye!
OK, so with a divergence of 0.25mrad, what is the energy density at, say, 150m, assuming the aircraft is on final approach at an altitude of 500 feet?
At 0.25mrad, the beam starts with a diameter of 4mm, and diverges to 41.5mm at 150m.
Area of a circle = pi x (r^2) = 3.14 x (20.75^2) = 1,352mm^2
10mW / 1,352mm^2 = 7.39uWmm^2 - below MPE of 10uWmm^2.
And I haven't even factored in the Atmospheric Spectral Scattering Coefficient of 0.25 for 532nm on a clear day, which would mean a 25% reduction of energy density.

So, what is the Nominal Occular Hazard Distance (NOHD)?
10mW divided by 10uWmm^2 to get number of square mm.
10mW / 10uWmm^2 = 1,000mm^2
convert area of a circle to diameter.
(/sqr (1,000mm^2 / pi)) x 2 = 35.7mm
Subtract the 4mm emergent beam diameter, and back-calculate mrad.
31.7mm / 0.25mrad = 126.8m. There we have have it. The laser energy density falls below MPE at 126.8 metres.
And for the last words, who can hold a laser steady on a target the size of a human head 150m or more away travelling at 300 Kph for a full 10 seconds?

Typical green laser pointer components.

On 08/06/2008, RedBack had this to add -The lasers in the news are actually shipped from America, and are considerably stronger than the typical 1mW laser (or even the 10mW) lasers that we see so cheaply available. The ones in question are made from the burning laser of a DVD Burning rom, and are available in excess of 300mW power. They are capable of bursting baloons, lighting matches etc...The law has been passed that they are illegal in NSW (always have been in VIC) But we're still allowed to have them in QLD.... For Now... M

On 11/01/2012, sfanojo had this to add -dcywVN , [url=http://hujhvkitxkox.com/]hujhvkitxkox[/url], [link=http://jnveycusrozq.com/]jnveycusrozq[/link], http://eawupcxugzky.com/

On 11/01/2012, jbqdlpyx had this to add -siEhCG , [url=http://hrhsewccafeo.com/]hrhsewccafeo[/url], [link=http://dpiunbjeauch.com/]dpiunbjeauch[/link], http://trnoqyuvplek.com/

On 11/01/2012, criqdr had this to add -VQCei6 , [url=http://ugmkfanpozbr.com/]ugmkfanpozbr[/url], [link=http://dnuyozfuoqsg.com/]dnuyozfuoqsg[/link], http://wpsclaykexon.com/

On 11/01/2012, fsrkxr had this to add -64vEfd , [url=http://xcolxtkiyppu.com/]xcolxtkiyppu[/url], [link=http://zufnvyaswtcf.com/]zufnvyaswtcf[/link], http://nhlvhyemtbdw.com/

On 11/01/2012, dlniugmjfrg had this to add -n1OTDQ , [url=http://rxyalehfamrf.com/]rxyalehfamrf[/url], [link=http://nagpiqcweixp.com/]nagpiqcweixp[/link], http://iyrdqsiyvojz.com/

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1193745713

About time I got to play with the good stuff.
Posted by Pauldos! on 28/10/2007

The military uses lasers for all the same applications that civilians use lasers for. They also use lasers for uniquely 'military' apllications. I have repaired and maintaned same-as-civilian-use lasers for the RAAF for some time now. I guess that a level of trust builds up with civilian contractors after a period of time, because in 1999, I got a call from the RAAF wanting to know if I could repair a certain laser for them, only they couldn't tell me too much about it. After asking a number of questions, to which the answer was - 'I can't really tell you that', I said that I would have to take to look at it. They called me back and booked me for a service call. When I arrived on base, I was led through the base to near the flight-line, into a restricted area. I was led into a building, and we went through a number of doors marked 'RESTRICTED AREA' in ever larger letters. There was a lot of men working in this building, and as a civilian in civilian clothes in a restricted area, every single one of them watched me continuously. It was very disconcerting. I was introduced to the laser, and told the problem. It was very difficult to figure out what was wrong with the laser system when I didn't know what it was supposed to do. Every time I examined an associated piece of equipment, or looked around the room, I was directed to keep my eyes on the job. It took some time, but I figured out what it was. I can't tell you what it was, not because it was top secret or anything, but because I wouldn't get to work on these things if I got a reputation for blabbing. Anyway, you can find out what the military uses lasers for through the wonders of Google.

Because I did not know what I was supposed to do when I booked the service call, I booked it not for a repair job, but an assesment only. When I was sure I had found the problem, I proceeded to take a picture of the circuit-board so that I could complete the assesment back at the workshop. When I pulled the digital camera out of my toolbox, there were gasps and I was told, very clearly, that this was a 'no photographs' area. As I was putting the camera away, they told me I could take a picture of the board as long as nothing else in the room appeared in the shot.

I was able to repair the laser, but as all three laser units were past their life expectancy, it took many such service calls keep them running. They even trusted me enough to send some of the associated equipment to my workshop to be repaired. Eventually, however, the lasers could not be repaired, and we sold them three new ones that we sourced from America. The paperwork for the export-of-technology rules was a headache.

Each time I went to the RAAF base for a service call, I was trusted a little bit more. The security at the base was a little bit tighter after 9/11, but as I was a known contractor, it was no problem. On a recent visit, I breezed through the security procedures because I am so familiar with them, while I listened to two American tourists insist that they had a right to visit the base because, get this, because they were Americans!! They argued for about 10 minutes until the guard called the MP's, who threatened to remove them by force. HAHA. Americans are so funny.

The last time I visited, I was allowed to examine, in detail, some of the more fantastic stuff in the room while the guys tested the laser. I gained an understanding of the systems far deeper than any Google result.

Keep the workshop locked

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1193557295

Sharplan 5000 refurbishment project
Posted by Pauldos! on 27/10/2007

I was called out to service two Israeli made Sharplan 5000 flashlamp-pumped alexandrite lasers, typically used for tattoo and hair removal. The output of these lasers is in the visible spectrum, low down in the red end at 755 nanometres.

The owner had bought them overseas in a non-working condition, and planned to use them in his body piercing studio for tattoo removal. He had gotten them for a good price and one was partially disassembled. He did not know why they were not working or even if they were complete. He was hoping that there was enough working parts between the two to at least get one unit operational. The one unit that was assembled and he had powered up reported a simmer error and did nothing else. I shudder at these kinds of jobs, where you have to bring back from the dead that which probably has no business being alive. You can spend many un-billable hours just to discover that they cannot be repaired. They did come with a maintenance manual in English, at least.

First priority was to get at least one laser up and running, so I started with the most-assembled laser, unit 1. Seeing as both lasers appeared to be in different states of abandoned repair, I figured it would be prudent to start with a full visual inspection of all the internals to make sure everything was present and connected. I have worked on a lot of Russian lasers over the years, and the internals of these Sharplan lasers looked awfully familiar. Components ruggedised and over-rated, like a 200 amp SCR carrying 10 amps, everything bigger and heavier than necessary... I would be willing to bet my lefty that the guy that designed these lasers was trained in Russia. You could detonate a nuclear bomb overhead and these lasers would still work. I have, in fact, worked with so many Russian lasers, and their technical manuals and schematics, that I can read most Russian technical specifications. But I digress...

The visual inspection showed that every component was present and connected as per the maintenance manual, so it was time to attack the faults as they showed themselves. The first fault was the simmer error. The simmer circuit maintains a small current flow in the flashlamp, called a streamer, so that there is no pre-ionisation delay when the flashlamp is fired. A check of this circuit revealed sufficient voltage to sustain a streamer in the flashlamp, so the flashlamp must be faulty. The owner of the lasers acquired two new flashlamps, and one was fitted to unit 1. As can be seen in the picture below, the flashlamp glass protrudes at each end of the pump cavity. When I went to change the flashlamp, something looked odd. In the picture below, there is a black lead connected to the red lead (anode) of the flashlamp, and a black lead with red toroids connected to the black lead (cathode) of the flashlamp. Is the flashlamp connected backwards? If so, could this be the cause of the death of the previous flashlamp? The maintenance manual indicated that this was the correct connection, and following the circuit indicated that this was the correct connection, but I contacted the manufacturer anyway, who confirmed that this was the correct connection. Once powered up, the simmer error was cleared. I fired the laser. Well, let's not do that again until we put the pump-chamber cover back on. The exposed flashlamp ends allow light to escape from the flashlamp, and these flashlamps are very large, and the light output is huge. I was completely blind for a couple of minutes, and I swear the paint on the walls of the room was not bubbled before... Another thing I notice was the loud metallic 'bang' associated with firing the laser. I fired the laser a few more times, after replacing the cover of the pump-chamber of course, and listened to the bang. It sounded like something was loose and rattling when the laser was fired. Then the laser stopped firing, and there was a distinct smell of electrical burning. I followed my nose to the discharge box.

The discharge box is connected to a big external capacitor bank charged up to a couple of hundred volts. The discharge box has a bloody great toroid about 400 millimetres in diameter and about 250 millimetres high, which has a single layer winding of copper strap 20 millimetres wide and 3 millimetres thick. Heavy duty. There is also a secondary winding, many layers and many turns of smaller wire. The electrical connections to the toroid were made with 10 millimetre bolts and spring washers. Here was the first problem I encountered. The connections to the toroid were burned and open circuit. I cleaned up the connections and fitted new terminals. The laser was firing again, but the new terminals still got warm. The peak current through those connections must be massive! The source of the 'bang' was also located in the discharge box. All the screws in the panels of the housing were loose, and large magnetic pulse associated with firing the flashlamp was causing the housing panels to rattle in unison.

Once the electrical faults were resolved, it was time to align the articulated arm. Unit 1 was easy, with only minor adjustments required to a couple of mirrors.

I won't go into a detailed account of the repair of unit 2. It was re-assembled, and similar, and other, electrical problems were resolved. When it came to the articulated arm, however, there was a big problem. The knuckles were very worn and sloppy on this unit, every time I worked my way through the mirrors, preceding mirrors would inexplicably go out of alignment. The owner of the lasers obtained an alignment jig from the manufacturer, but it was no use, I still could not align the arm. It was just too badly worn. The owner did not want to spend any more time or money on unit 2, and the repair was abandoned. The lesser objective of making one laser out of the two, however, was a success.

Note the exposed flashlamp glass at the top and bottom of the pump chamber.

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1193488272

Let's add RF burns to the injury list.
Posted by Pauldos! on 26/10/2007

Recently I was asked to repair a Coherent-Scientific RF-excited 500Watt sealed CO2 laser. The customer reported that the laser failed one day with low output power, and showing 'Low Forward Power' and 'High VSWR' indicators. The customer had approached Coherent Scientific in Adelaide for help, but as the laser was never officially brought into Australia, their support was limited to offering to ship it back to the factory in the USA for him.

There are two main components to the system - the RF generator, and the laser head. I started with the RF generator because the RF-excited laser head I do not have much experience with, and as far as I know, the two main components of the laser head are voodoo and black art.

According to the owner's manual, the RF unit generated 1200 Watts at 81 Megahertz. I started by taking the covers off and performing a visual inspection. The RF generator consisted of a 81 Mhz signal generator feeding a distribution amplifier, into an 8-way wilkinson divider, in turn feeding 8 RF power PCB's. The RF power boards were mounted on a water-cooled heatsink plate, and all fed off a 40V bus bar. The RF power boards each consisted of a MOSFET pre-driver feeding two push-pull MOSFET power amplifiers through a wilkinson divider. The outputs of the two power amplifiers were fed into a wilkinson combiner, then off the board and into two large, water-cooled 4-way wilkinson combiners along with the other RF power boards, and then into a larger two-way wilkinson combiner and to the output connector. There was a couple of stripline directional couplers on the output as well, to sense forward and reflected power. A number of the power resistors in the 4-way combiners had failed in a spectacular way, as had a number of power resistors in the combiners on the RF power boards, and a few RF power transistors and pre-drivers as well. As those high-powered components would have made quite a bang when they exploded, I asked the customer if he had heard any noises when the unit failed. He had not. As there were a couple of component failures that indicated over voltage, I asked him if there were any power disturbances or the like at the time the unit failed, or if any other equipment in the factory failed, or any of the adjacent factories reported any equipment failures. He had not noticed problems with anything else.

I obtained specifications sheets for the transistors. I calculated that each power amplifier generated 100 watts, and with two power amplifiers per board and 8 boards, that's 1600 Watts. Allowing for losses in the wilkinson combiners, 1200 Watts out sounded about right. I began by taking a death toll, and started testing all the transistors and resistors. Each transistor had to be isolated and tested individually, and when it was all done, there were more transistors that had failed quietly than had exploded. This testing took some time, and the customer was itchy to have his laser back up and running. I took exception to the incessant pushing and retorted affirmatively that it would not be in his interest or mine to rush this repair. Pinpointing the cause of the failure was going to be crucial to preventing it from happening again. At these power levels, failures are spectacular and expensive, and we would be both back to square one if it wasn't resolved before going back into service. But what was the cause? Could it be a power surge? That would account for the many failed components. But then again, in a balanced system such as this, a single spontaneous component failure could upset the balance and cause a cascade of failures. Could it be a faulty laser head? The RF unit has high-VSWR protection, so probably not, unless it is an intermittent fault. I have seen type of failure this before, where the protection circuitry just can't respond to the fault condition as rapidly and repeatedly as the intermittence.

So, first things first. Repair the RF unit. The power resistors for the wilkinson combiners were able to be sourced here in Australia. Philips, the manufacturer of the MOSFET power transistors had none available for 6 weeks. The customer offered to chase up Philips parts stockists himself for any that might be laying around on shelves, so I left the sourcing of the transistors to him while I tackled the RF unit. I reverse-engineered the control board, and then built a jig to substitute for the control board so I could drive the RF unit my way. I removed all the failed transistors from the RF power boards, and began further testing of the remaining good transistors. Each transistor, both drivers and pre-drivers, have a trimpot to bias the transistor in the centre of it's linear region. I powered up each board individually at 20 Volts, enabled the bias circuit, and charted the current draw of each transistor. When the new transistors are fitted, each will have to have their bias trimpot set so that the transistor draws the exact same current. Due to manufacturing tolerances, each transistor has slightly different properties, so each transistor will have to be set individually after being fitted. Once this was done, there was nothing to do until new transistors were sourced. I wasn't sitting down for long before the customer came in with a box of transistors. He had found a supplier - how resourceful! Errr... what the hell are these? I didn't actually say that, but I did ask him where he got them. In China. They were stamped 'Philips', but they did not look quite like the original transistors. The tabs were scruffy, and cut at imprecise angles, like they were cut with tinsnips. And the tabs were not gold-plated phosphor-bronze, more like something-plated tin. I thought I better test them before I fitted them. I had Philips datasheets for the transistors, and the current-vs-bias graphs that I had plotted myself, so I built a test jig and tested them. The bias regions were all over the place, some were non-linear, some had high channel resistance, and some did not even turn on! So this what counterfeit components look like. I have read about counterfeit parts in the electronics engineering journals, but I had never seen them before. I informed the customer that the parts were no good, and showed him the graphs. He was disappointed, and vowed to get his money back. I ordered the genuine parts from Philips in the USA and waited. Once they arrived, I tested them, they were perfect, and fitted them to the RF amplifiers. I set the bias points, and checked the output power into an RF power meter for each board. I checked all the connections at each stage, to make sure there no intermittent connections. I re-soldered the output connector for good measure. Now to plug it into the laser head.

Back at the factory, I checked the RF cable for intermittent connections before plugging it in. I took the connection panel off the laser head to inspect the internal connections there, and it all looked good. My RF power/SWR meter cannot handle the high power output from the RF unit, so I tried to source one elsewhere. The test equipment rental companies had no such instrument, and asking around the local two-way radio dealers came up nothing, either. Looks like it's the 'suck it and see' method. I powered up the laser. It seemed to be working, and the customer declared that he was getting better power now than before the repair. So it could have been just spontaneous failures, a number of failures over time until it just wouldn't go.

Several weeks after the repair, I heard from the customer. The laser was working electrically, but the laser head output had dropped to an unacceptably low level. So it could have been the laser head all along. I had a suspicion it was. The last I heard, he had shipped the laser head back to Coherent Scientific in the USA for refurbishment, and was onto a spare RF unit going cheap - in China.

1600 Watts of power, keep away from Ham Radio Operators.

On 11/01/2012, zdnyjo had this to add -oFiB2l , [url=http://gsfzzgittiki.com/]gsfzzgittiki[/url], [link=http://nioomxqfyaiq.com/]nioomxqfyaiq[/link], http://caocslkgipcx.com/

On 11/01/2012, xeqevshnyo had this to add -233HeA , [url=http://bywxcsnwulhg.com/]bywxcsnwulhg[/url], [link=http://plrsbfkfeopa.com/]plrsbfkfeopa[/link], http://tbtrxzlwunjj.com/

On 11/01/2012, cceisq had this to add -VKwXtO , [url=http://xuptsprncdrc.com/]xuptsprncdrc[/url], [link=http://uomveiygfuan.com/]uomveiygfuan[/link], http://hejxmwttedkg.com/

On 11/01/2012, ugfrpmbth had this to add -kIkNHS , [url=http://kmmrlfjcgnde.com/]kmmrlfjcgnde[/url], [link=http://nstteesrafrj.com/]nstteesrafrj[/link], http://mjjrhbgfsier.com/

On 11/01/2012, waroahe had this to add -nukoIl , [url=http://hieayifroenf.com/]hieayifroenf[/url], [link=http://mnnphxumvmlt.com/]mnnphxumvmlt[/link], http://pmibxergvfpy.com/

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1193401811

Extending the life of Topcon RL-50B and RL-60B lasers.
Posted by Pauldos! on 23/10/2007

The Topcon RL-50B and RL-60B levelling lasers use a fairly unique compensator arrangement. Most levelling lasers use a suspended compensator arrangement, with a lens or mirror on the pendulum. The pendulum is usually metallic, and inside another metallic barrel, so that an electrical connection between the pendulum and outer barrel indicates to the electronics that the compensator is 'out of range'. The RL-50B/60B has a fluid compensator system where the laser beam is reflected off an interface between the fluid and a window, with the level of the fluid influencing the reflection angle of the laser beam. Because there is no electrical aspect to the compensator, an optical system is used to detect when the compensator is 'out of range'. In the output structure of the laser, a glass window at forty-five degrees is used to reflect a small portion of the beam to a photodetector. When the laser is level, the small portion of laser beam strikes the photodetector.

A common fault with these lasers is to constantly indicate 'out of level'. This occurs when there is insufficient beam intensity on the photodetector. The standard solution for this fault is to clean the 45 degree window. Sometimes, this does not bring the laser back to life. I have stripped down a couple of these lasers to try and figure out what is going on.
At first, I thought that maybe the laser diode could be down on power, reducing the available beam, but I quickly discounted that, because the laser diode output is feedback controlled, so the output power is stable up until the point of complete failure. One of the units I disassembled had cracks in the compensator housing, and the fluid level was low. I don't know whether the fluid leaked or evaporated, but in either case, there was no way the compensator could be repaired. In another unit, I noticed that the fluid was discoloured. Since I don't know what the composition of the fluid is, I don't know what could cause it to discolour. Perhaps extremes of heat or cold may damage the fluid. If the fluid is discoloured, that may reduce the available laser power at the output. The question is, can we compensate for this? (pun not intended)

I decided to reverse-engineer the photodiode circuit, and see if there was any way to improve it. There is. The photodetector amplifier is a standard op-amp inverting amplifier. The feedback resistor, surface mount R23, is 470K. I changed this resistor to 680K to increase the gain of the amplifier, and bingo! the laser works like a real one again. Extensive testing in the workshop and in the field shows that the laser functions as originally designed in all ways. I have done this modification to over fifty of these lasers now, and the modification extends the life of the laser anywhere from a few months to a few years, with the average about one and a half to two years. Customers are always happy to not have to buy a new laser for another year or so, so this modification is always embraced when offered. I have never figured out what is going on with the fluid, but since I have a solution (again, pun not intended), I don't care.

RL-50B/60B main PCB, R23 up the top there.

On 25/12/2009, Mike had this to add -I have a Topcon RL-50b that signals out of balance constanly. Can you e-mail me directions on how to clean the lense? I am in central Texas USA. deermike@beecreek.net Mike

On 25/02/2010, Dave had this to add -I have the same issue with a RL-60b. Could you do the same for me and email me how to clean the lens? dbrunsting@abonmarche.com

On 17/04/2010, Pauldos had this to add -A cleaning procedure is on the way.

On 17/06/2010, Matt had this to add -Hello Pauldos! I recently purchased an RL-50B from Ebay. It will spin up for a second by tilting it back and forth and then shut down. I replaced the resistor and cleaned the lens. That didn't do it. I noticed the main gear is wavy between the screws. Could this be a problem with the diode not reading that is causing fault? I have not taken apart the styrofoam capsule yet.... Any suggestions would be helpful! mjwilbur2001@yahoo.com

On 17/06/2010, Pauldos had this to add -@Matt : Don't take apart the styrofoam enclosure, there's nothing there for you to do. I don't understand what you mean by 'the main gear is wavy between the screws'. If the laser started up at some point when moving it around, it is possible that the bubble is out. Level the laser till it runs, then adjust the bubble. Lots more info on repairing this laser is coming to the new website.

On 09/08/2010, Adam had this to add -Pauldos, Thanks for posting this info. I replaced the resistor in a unit a few months ago, and brought one back to life. Now more units are showing up at my desk...

On 18/09/2010, David had this to add -I have an RL-60B. It registers out of balance constantly and will occasionally turn on. I noticed the comments about cleaing the lense. Could you also email me directions on how to clean the lense?

On 28/09/2010, Adw had this to add -Can I get those cleaning instructions please? Aaron.wallace3693@gmail.com

On 28/09/2010, Pauldos had this to add -O.K. Here's the short version. Remove the housing. Remove the battery holder. Loosen two small silver grub screws on the turret. Lift turret off. Clean slant window with acetone and a cotton bud. Avoid smearing the glue in the corners over the window. Flatten and curve a cotton bud to clean the inside of the slant window. Clean the folding mirror under the slant window. Replace the turret. Turret has a small amount of play, so align it for best operation before tightening grub screws. Re-fit battery holder and housing. All done!

On 08/11/2010, jason had this to add -I have a RL-60B and all it says is that it is out of level. Laser won't spin. If there is a way to repair this myself could you e-mail me how at jasonstriplin@comcast.net.

On 06/01/2011, andrej Slovenia had this to add -Pauldos you realy are enthusiast, an expert and a good man. I wish you well. And if it happens, that you come to the old world, I will be honored to have you as the guest in my home, located in Slovenia.

On 04/11/2011, aurélien had this to add -Hello Pauldos, I have the same issue than Jason above, with a RL-60B. The out of level LED is always blinking and the laser won't spin. Could you give me some gidelines to repair it, please, my mail : aurelien26200@hotmail.fr.

On 16/11/2011, Gabriel visezcamorgmailcom had this to add -Hello Pauldos. I know this is an old article but maybe you are still arround. I have an RL-60B laser level and it wont spin. The red LED is always blinking when the laser is turned on. The laser will spin if touched by hand of the photodiode contact alimentation. Taking into account that the laser beam is invisible I cant bring the laser beam into the photodiode. I read the article and I'm interested on how to verify the functionability of the laser diode because I cant see any beam in the optical system. I will check the liquid later because it seems alot of work to do. I didnt measure the R23 because I cant seem to know if the laser diode is emitting. Thank you in advance and maybe can you help me with this problem :)

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1193142611

Darling, I'm having an affair...
Posted by Pauldos! on 22/10/2007

I think that it is something that happens when you get intimate. Before you know it, it's love. I went home and I said to my girlfriend - 'I'm in love with a TEA laser'. 'Don't say that too loud,' she quipped, 'the computer will get jealous.'. Ha. Bloody. Ha.

I have been maintaining a Transverse-Excited-Atmospheric (TEA) laser for a contact lens company for years now. They use it for engraving, labelling and drilling of contact lenses. As the name suggests, the TEA laser is a CO2 laser that operates at atmospheric pressure. The electrical discharge is transverse to the beam path. In order to get a plasma flow, very high voltage is used. 35KV, that's 35 thousand volts. Scary. X-rays.

Recently I was called to service the laser, with the complaint that the beam was weak. An inspection revealed that the folding mirrors of the beam delivery system, and the output mirror of the laser, were very contaminated. The contamination on the first folding mirror of the beam delivery system had been burnt onto the mirror. I cleaned all the mirrors, tightened the sundry loose screws and bolts, and re-aligned the beam delivery. I re-aligned the laser tube with the output port to minimise beam contact on the area of burnt contaminant.

Two days later, the customer called back and told me that at the morning's start-up, during the purge cycle, the laser made a 'foomp' sound and now would not fire. Once the cover was off the laser, the fault was apparent. The front of the laser had fallen off. As can be seen in the picture, the rear plate is attatched by a very sturdy clamp arrangement, but the front plate is held on with two-part epoxy resin. Presumably the epoxy was weakened when I moved the laser tube two days earlier, and the positive pressure during the purge cycle blew the front off. I checked the purge pressure, 3 psi, not excessive at all. I reverse-engineered the gas system, which led me to check the 7 micron gas outlet filter. Blocked. I back-flushed it with acetone, and it was good again. Now I had to remove the whole laser tube, so that it could be stood up on end and glued back together. I pretty much had to disassemble one entire side of the laser to get the laser tube out. I removed the thyratron, high voltage box, sensors and cooling system, documenting all the coolant and gas lines as I went. The coolant lines were pneumatic hose, not suitable for liquids, so many of them disintegrated on removal.

After the laser tube was glued back together, and the laser re-assembled, it was time to align the front mirror. With these short-pulse CO2 lasers, human skin makes an excellent alignment tool. Holding my hand in front of the output mirror, I repeatedly fired the laser while walking the front mirror around. It didn't take long to find the beam, as the skin on my hand lit up bright white with each pulse, with the exact pattern of the beam clearly visible. I found that firing the beam into the same spot on my hand would leave the skin white with surface burn, but the depth of the burn was very shallow and there was no pain. It healed in a day. I aligned the mirror by firing the beam repeatedly into my hand until the alignment was perfectly square, with the horizontal striations clearly visible in each flash of my vaporising skin. I re-aligned the beam delivery system, and the customer was happy again.

During the repair, I replaced a number of hoses, replaced the coolant, cleaned the coolant pump, changed the fan filters, cleaned all the electrical parts, tightened all the bolts and replaced the missing ones, and tidied the laser up in general. Two full days was spent on this overhaul, and I know just about everything there is to know about this laser. This laser and I have been very intimate.

How can you not love something you are so familiar with?

Add Your Comment to This Entry Article link : http://www.pauldos.com/lasers/article.php?article=1193056211

(c)DOSBlog. by Pauldos! Software. www.pauldos.com
603 People Have Viewed This Blog.