473nm DPSS 200mW SNOC Electronics – Distorted Dot with Artifacts

[madmacmo]

After several unsuccessful bids on previous 473nm DPSS Ebay listings I finally had a winning bid on the one below:
473nm 200mW Blue Laser with Analogue Modulation - eBay (item 140568560886 end time Jun-28-11 20:40:23 PDT)

However after receiving the unit I discovered a significant problem with this laser is which the beam dot becomes distorted and dark artifacts appear as distance is increased. Note the images below are of the dot through an approx 2 O.D. Blue/Green lens (taken from a pair of protective glasses in order to reduce the brightness of the dot so that it could be adequately observed - albeit rendering the dot a dark red) at distances of 70mm, 2.5 meters and 12 meters. The artifacts begin to appear distinguishable at 2.5 meters and are very pronounced at the 12 meter distance. There is no outside adjustable lens or focusing assembly.

Note within the images below where the dot diameter is 3mm at 70mm, ~8mm at 2.5 meters, and ~20mm at 12 meters

I contacted SNOC asking if this is something that could be user corrected. Their response was “the optics could be distorted” and that “It needs profession repair. But if you are engineer, you can try it.”

My request is if anyone has a recommendation(s) as to an LPF member in the US that might be willing to look at it.

As I would really rather not ship it to SNOC (to China and back) for what might end up cost wise more than this unit is really worth. I would be willing to provide equitable compensation should anyone be willing to expend the technical effort.

I also observed the Non IR Filtered Output at an impressive 457mW at 4.5VDC Analog Input.

The distortion and artifacts did not change when I inserted IR filters. However, I will have to defer to someone with the ability to determine what the true IR component may be, as I am unable to ascertain the technical difference between the two coated glass IR filters that I utilized The LPM readings are significantly different between the two.

MIL-G-174 Glass from Laserz4sale - 4.5VDC Analog Input - at 361mW
FS: IR filter for green DPSS Laser

FTR-IR Filter from RadiantRlectronics.org - 4.5VDC Analog Input - at 212mW
Small IR Filter

 

[lasersbee]

Re: 473nm DPSS 200mw SNOC Electronics – Distorted Dot with Artifacts

I don't see any images....
What LPM did you use to get the 457mW reading..??
Looks like the 2nd filter is the one...

Jerry

 

[lasersbee]

Re: 473nm DPSS 200mw SNOC Electronics – Distorted Dot with Artifacts

Yeah... that looks crappy... maybe someone will chime
in to help you...

You could also try getting help on PL..
They use a lot of Labby Lasers over there...


Jerry

 

[Cyparagon]

I believe you have discovered the fabled mode of TEM¿§±

 

[HaloBlu]

^ I seen that once before, it appears to be the legendary TEM¿§± but its actually just haunted. Keep it away from vulnerable young children until you can get it taken care of.

 

[BShanahan14rulz]

Not meaning to sound like an ass, but have you tried cleaning the aperture window or lens?

 

[532 with Envy]

Have you tried taking the main case apart and giving it a good cleaning.
I'm sure it's well used and the fans may have deposited debris over time into the main chamber. In the photo's it still looks like some kind of coating or blockage over the optics, perhaps on the inside of the lens.
I'm not an expert by any means, just throwing out another suggestion.

 

[Deleted member 10578]

After several unsuccessful bids on previous 473nm DPSS Ebay listings I finally had a winning bid on the one below:
473nm 200mW Blue Laser with Analogue Modulation - eBay (item 140568560886 end time Jun-28-11 20:40:23 PDT)

However after receiving the unit I discovered a significant problem with this laser is which the beam dot becomes distorted and dark artifacts appear as distance is increased. Note the images below are of the dot through an approx 2 O.D. Blue/Green lens (taken from a pair of protective glasses in order to reduce the brightness of the dot so that it could be adequately observed - albeit rendering the dot a dark red) at distances of 70mm, 2.5 meters and 12 meters. The artifacts begin to appear distinguishable at 2.5 meters and are very pronounced at the 12 meter distance. There is no outside adjustable lens or focusing assembly.

Note within the images below where the dot diameter is 3mm at 70mm, ~8mm at 2.5 meters, and ~20mm at 12 meters

I contacted SNOC asking if this is something that could be user corrected. Their response was “the optics could be distorted” and that “It needs profession repair. But if you are engineer, you can try it.”

My request is if anyone has a recommendation(s) as to an LPF member in the US that might be willing to look at it. :anyone:

As I would really rather not ship it to SNOC (to China and back) for what might end up cost wise more than this unit is really worth. I would be willing to provide equitable compensation should anyone be willing to expend the technical effort.:beer:

I also observed the Non IR Filtered Output at an impressive 457mW at 4.5VDC Analog Input.

The distortion and artifacts did not change when I inserted IR filters. However, I will have to defer to someone with the ability to determine what the true IR component may be, as I am unable to ascertain the technical difference between the two coated glass IR filters that I utilized :thinking: The LPM readings are significantly different between the two.

MIL-G-174 Glass from Laserz4sale - 4.5VDC Analog Input - at 361mW
http://laserpointerforums.com/f39/fs-ir-filter-green-dpss-laser-49070.html

FTR-IR Filter from RadiantRlectronics.org - 4.5VDC Analog Input - at 212mW
Small IR Filter

I think you should just bite the bullet and send it back to SNOC for repair or replacement. Once someone else opens it, the warranty will be void and it's doubtful about it being repaired as it looks like perhaps an optical or crystal defect.

I also would not trust the IR filters you posted the link to.
These are very similar to many I've seen that are made with plate glass and only block a small percentage of the IR. You should get a real IR filter from edmund optics (they are around $30 USD or so for a 25mm diameter) To be trusted you need to get one where they at least provide a chart showing transmittance vs wavelength. Not that they won't help some with reducing IR, but to block all the IR with these I would guess you would probably need a stack of about 10 of them and by the time you do so, with that many of them stacked, you would be losing at least 1/2 of all light to surface losses.

 

[Bluefan]

What IR filter did you use? The transmission at 473nm may be lower then expected. A piece of red acrylic filters out blue very effectively but is completely transparent to IR, this way you can measure the actual IR output.
The beam profile doesn't look like a TEMwtf profile. This is a 3 level laser, and higher order mode will have very high losses, so a complex beam profile is very unlikely anyway.
It really looks like the optics after the cavity are dirty or damaged. If you open up the laser you can see any dirt or damage because it will light up because of all the scattering.