Review: 473 nm 100 mW Jet Lasers PL-E Pro „Sky Beauty“

[Radim]

Thanks for mentioning that, astralist.

I came out from what JL say about it at their webpage and I even confirmed it in our email discussion with Gray during the selection process - "Yes, the 473 nm is IR filtered no IR residual."

I'm extremely careful with that (requiring all DPSS using IR to be filtered) as I work often close to the beams and without glasses during laserpainting. For practical reasons, but still keeping strict safety protocol and considering it as high risk laser operation - special extra care is taken and special conditions have to be met to do that and here a little disclaimer (for other readers as well): I DO NOT RECOMMEND TO DO THAT, without extremely strict safety protocol followed, this practice might lead to serious and severe injury! YOU ABSOLUTELY HAVE TO USE PROPER EYE PROTECTION WITH THIS LASER!

Regarding JL webpage: It is not mentioned here - at this laser page, but mentioned here - 532 nm version. Maybe just an update issue.

Also how old is your laser? AFAIK JL are developing and improving their lasers, this might be the issue with your laser. Anyway good to mention here, to let others aware in case of purchasing second hand laser.

In addition - during my tests, I took the output dot pic with mobile camera (not published) and it was not that different from eye view - if there is massive IR leakage I would expect to appear on mobile cam pic.

Edit: Maybe I need to look at the aperture window more carefully when I have this dilda in hand again, It seemed to me to be purple/reddish coated - depending on ligting, if I remember it well.

 

[astralist]

My version is just one version before your version, i forgot the exact time, but mine was their last stock of that model.

I discovered about the truth accidentally,
when rubbing the front glass, there are some aluminum residue from the front thread which scratch the glass as i rub the glass with microfiber cloth.
As the scratch worsen the beam profile, i decided to replace the front glass and searching IR filter on aliexpress. Replacing the front glass is easy, you just need to use hot air to melt the clear epoxy.
And then one the IR filter arrived, i'm quite surprised by the fact that IR filter from aliexpress was more greenish and with red tint on the surface (with the color is more opaque), then there it is, i tested both with IR 808nm laser only to find out that JL front window is only a BBAR window.

I'm quite surprised at that time but since i had no time to review the unit, so i decided to ignore it, also the fact that without front window the IR leak is about 50mW at max for such 900mW peak of 532nm, i think the other member will do just fine i guess.


EDIT:
back then they also claim that it is truly an IR filter, and as far as i remember, there is no one here trying to review/investigate about the front window

 

[paul1598419]

I've handled these IR filters many times, but never noticed the red reflection off the surface. Maybe I didn't have it at the right angle. When I have time, I'll pull one out and have another look at it.

 

[astralist]

I've handled these IR filters many times, but never noticed the red reflection off the surface. Maybe I didn't have it at the right angle. When I have time, I'll pull one out and have another look at it.

You can try shining it using white light (6500K) at 45 deg while you see its reflection on the opposite angle.

 

[Radim]

Guys, I've just returned home and as being curious, I took a quick look on the front window. I cannot say the color of the material by looking through this. At the edges where glued it looks red/purple, in centre clear, but really hard to say. When illuminated with UV filtered 12 V 50 W GY6.35 halogen bulb of my lamp on full power it looks like this (mobile cam photo - just to capture it fast):

(BTW: I've just removed a bit of dust from it with filtered blower baloon I use for camera lens and sensor cleaning - good to use to remove stuff.)

But still I cannot recognize with my tired eyes (very loong day at work and large part of it staring on screen) if it is material itself or just a reflection of the surface (seems more like reflection now, but really not sure as I'm so tired that I see quite bad now)... Maybe I need to do some proper photo of it later.

I also tried to split the beam through diffraction grating looking with mobile camera for additional dots not seen with eye - I discovered none.

My mobile cam captures IR quite well AFAIK, however I'm not sure at what range - I guess as typical IR remote is 940 nm and IrDA is like 850 - 900 nm. I'm sure that I can see IR from remote control by my eye as a dim red. With my mobile camera it is very bright. I think 808 nm should appear there as well if the leakage is significant. It's hard to say without proper equipment.

In addition here you can see YT video with IR filter and its red reflections (from time approx 1:00):

I have no reason not to believe JL as they are reputable company and if they claimed something not being true and concurrently knowing they are delivering to LPF members, that would be not really worth a risk of loosing the reputation IMO.

Maybe I should get Gray aware these concerns, to confirm and specify here how is it filtered exactly.

 

[Razako]

Nice review, I wouldn't worry too much about the IR filtering assuming that gray personally said they have it. Seems like it should be easy to test if you have laser goggles and a camera that can pick up IR.

 

[paul1598419]

After watching the YouTube video, I can see the red reflection quite clearly, so that saved me from digging through a bunch of stock to try to find those filters. :thanks:

 

[astralist]

That looks like a genuine IR filter to me!

Lets just hope that in my case, they just misplaced the waterproof glass instead of IR filter.

 

[paul1598419]

I never understand the worry people have about IR from DPSS lasers. First of all, it's not like the path of the IR is different than the path of the visible light. Secondly, the amount of IR leaking out is small compared with the amount of visible light. This is true even among the cheapest DPSS lasers. I have confirmed it with a spectrometer.

 

[astralist]

While the path is not entirely different, some green (that i have) is outputting IR in different angle than the visible light.

like i said before, without front glass, my 800mW 532nm JL outputting about 50mW of IR which is good, versus a least efficient one (saw it somewhere here years ago) which the IR is almost 1/3 of output power.

It is more like a classical fear that the IR power is almost a half of the laser's rated power or dominates the entire DPSS system.
IMO, he only our genuine worry is if the rated power includes the power of IR, this apply to non reputable source of laser

EDIT:
Also, we might fear that when using red goggle to block 532nm, the IR still passes the goggle.

 

[paul1598419]

If the path is different, it is diverging quickly as it exits the laser. In this case, still no problem past a few feet. If it is collimated, it has always followed the visible light path, still no problem. I have never seen one that had a third of its output as IR. I'm not saying you aren't right about the one you saw, it is just very rare. Now as far as getting past red goggles, I have never come close to hitting anyone or myself in the face with a laser's beam. If someone has, it is probably better if they find a different hobby.

 

[astralist]

You are right. There should be no difference handling the IR leakage other than handling the visible laser output carefully.

InfinitusEquitas said based on his experience, the IR can be from 2 to 60%
http://laserpointerforums.com/f44/ir-leakage-74675.html#post1078780
Concern of IR leakage are quite hot topic back then the before/ the moment i joined LPF.

My old 250mW 532nm laser from Rayfoss which is pretty much dead (rayfoss said the crystal was no longer usable), it only emits ~50mW green with ~500mW of IR leak.
Now it's been disassembled only to become a 1W of 808nm laser

 

[Radim]

Yes, the IR residual should be spreading much more. Still for my purposes it is important - as I mentioned earlier, I often operate close to beam (not like putting my head like ten cm next to it, but at let's say half an arm distance) even near aperture and with using optics, so I just want to see where the potential danger exactly is before I approach the laser in operation. Also some glasses do not have IR filter, so for close range burning for example the bright IR dot might cause some damage in eye with prolonged use in case of high IR leakage. The intensity of IR might be quite high even if not collimated and the point is to make sure MPE is not exceeded (for IR and other wavelengths out of visible spectre, this is to be considered differently in terms of laser output power relation - no blink reflex protection). If I wanted IR, I would have gone for IR laser.

My Univet goggles are covering also concerned IR range (with high OD) together with violet-green region, so if I want to burn/engrave stuff with DPSS I can make myself sure I'm (double) protected.

But anyway, now I'm much calmer that there is no (or very little) IR leakage from the reviewed laser. Thanks again for rising this discussion.

 

[Radim]

Nice review, I wouldn't worry too much about the IR filtering assuming that gray personally said they have it. Seems like it should be easy to test if you have laser goggles and a camera that can pick up IR.

Good point. However I do not want to test it on my goggles/glasses I use (if I do it, I could not use them anymore for eye protection). Maybe I could find the old T-Rex crap, I used for burning (like burning the glasses). But still it is not a solution as these are just orange plastic, not proper eye protection.

So, for the others - quality eye protection costs some buck, do not waste your money by buying cheap crap.

 

[astralist]

If you have a genuine concern about this IR, you might want to follow these step:

• Get yourself a cheap IR laser (808nm). Why 808nm? because the 946nm or 1064nm are always got reflected in the cavity to form an output coupler.
• Grab a cheap camera which don't use IR filter (my smartphone's back camera are IR filtered, but idk the others)
• Shine the 808nm laser to your DPSS laser's front glass through the inside barrel
• Look for the IR beam illuminate the inside barrel, if you found it then you might need to replace the front glass as it is most likely not an IR filter.
• Please do extra careful when pointing the IR as the reflection might get into your eyes.

Stay safe! :beer:

 

[Radim]

Very good point, astralist. Thanks for the tip.

I just add one more point - be careful also about the camera. Cameras are sensitive too. Make a static setup of laser test aparatus with camera lens protected and use camera carefully after everything is ready (do not forget proper eye safety wear for IR) - consider laws of physics in optics.


BTW crystals should protect pump diode from direct hit, I assume - maybe it is better to spread IR beam with lens not to have it collimated.

I would appreciate opinions whether this test cannot damage the pump diode.