Review: SKYlasers (laserbtb.com) H532L-100B 100mW 16340 532nm Laser

Hey Everyone, time for another review!

I just got this guy in today, and so far I'm pleased with the service and shipping. I purchased the laser late on the 19th, which would be mid day on the 20th China time. It arrived today the 27th. Not bad, but remember this was DHL. It didn't get held up at customs and was well packed. DHL security did open the outer packaging, but did not open the interior packaging.

One interesting thing; it did not ship from the SKYlasers address which is on the FDA RED LIST, instead it is marked as having come from "Shenzen OME Info inc". It was also marked as an $18 "Flashlight without battery installed", I suspect this is how it made it through customs.

I love these hosts, safety hosts are cool on high powered lasers. The laser comes in a nice, solid, well made faux-leather wrapped box with form fitting high quality foam in it.

The laser itself:
It feels well made and there are no red flags popping up from initial inspection. Upon powering up the laser I noticed a small amount of instability, but it seems more like it is warming up and hitting various output level plateaus.

I whip out the LPM and do some tests:




Okay, this laser is NOT IR FILTERED. However, it peaked at 210mW (532nm + IR), and those goggles do let through about 2.5mW of 532nm. I retested using my eagle pair and wearing the shitty ones you see in the photo, but did not want to have it set up long enough for another photo, I value both my eyes and the eagle pair, and narry like to separate the two. With the eagle pair, which let NO 532nm through, we get a solid reading of 40mW IR @ 205-210mW raw output.

So, so far it is looking amazing, right? 165 to 170mW of 532nm light with only 40mW of IR. That's 110% over spec, with only 20% of the total output being IR.

The Bad News:
This laser is NOT TEM00. It mode hops continuously. It does sit in TEM00 for a short portion of the on time, but it isn't like thermal fluctuations are causing the mode changes, it just continuously works it's way through modes. Fortunately the divergence is excellent when TEM00, and still very good even with the mode hopping. You would not be able to tell it was mode hopping without expanding the beam with a lens (adjusting focus) or being at the target with the laser at distance.

So far I've been able to identify:
Cyllindrical: TEM01 TEM03 TEM11 TEM21 TEM21
Rectangular: TEM01 TEM02 TEM22

And of course, TEM00 randomly in between all that.

So, for general purpose pointing, or starpointing, amusement, fluorescence, and other non critical uses, it is adequate. This laser would not be of any use for holography or data transmission.

For $50, I'm satisfied. Could it be better? You bet. Nail it down in TEM00 and this laser would be perfect.

Note; while LaserBTB/SKYlasers is trustworthy to purchase from, and lasers do indeed appear to come on spec, if not over spec, one should remember that they ARE on the FDA Red List and thus there is a chance your laser could be siezed or you could be fined.

Others who own one of these lasers, I'm interested in hearing about your laser's modality.

UPDATE: Added video of mode hopping:

http://www.youtube.com/watch?v=H6Lg-RdSVlM

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

Thanks for the review and good to hear it arrived safe and sound!

I had a question regarding how to safely LPM a laser with unknown IR. Were you concerned at all with looking at the dot hitting the LPM at close range while doing the testing before you knew how much IR was present? Would the 40mW that you discovered be a bit much to look at up close without duel protection goggles while doing the testing? I hope you don't mind as I am learning I am trying to better understand the threshold for what is safe and what is not.

I feel like I need to enroll in a University course full time to get caught up with everything there is to know! I have done quite a bit of reading on here but haven't found anything that explains TEM and the characteristics, definitions, reasons for different TEM modes etc. Is there any threads or external links that cover TEM from the ground up? I would love to know more so I can better understand your assessment of your new laser! :thanks:

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

No problem. Go to wikipedia and type in "Transverse Mode", that should help ya out with modes.

As for the IR; it really depends, when we're dealing with <50mW IR the deciding factor is mostly the green that comes with it.

Example: on a >100mW laser which requires extreme caution during use, an extra 40mW isn't too much of an issue. You're going to treat the laser as a firearm anyway, so what if the bullet is a little sharper than normal.

Example: on a 30mW laser which you'll point around a lot with little thought other than the obvious "is this going to reflect back to my eye"... 40mW IR is much more of a danger.

The above does NOT apply if you plan on burning with the laser though, you need to either add an IR filter to the laser or get dual stopband goggles to protect your eyes.

Hope that helps.

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

Thanks Sigurthr, I checked out the wiki article it's a great place to start. Looks like there are lots of other terms and definitions to follow up on as well that I think I'll need to read up on: Boundary Conditions, Gaussian Beam etc.


That definately makes sense about the "sharper bullet" analogy with the extra 40mW IR on top of an already significantly dangerous 100mW+ green. In regards to looking at IR up close I guess I am wondering what the threshold of safe distance of looking at X mW of IR up close is. If you are protecting yourself with Eagle pair non-IR absorbing goggles that are stopping the green, do you need to worry about looking at the 40mW IR while staring at the dot up close while measuring the mW? I would think this would be the same danger as with burning with the laser up close and staring at the IR spot?

Thanks again, I'll leave the floor to others after this last question. I know you are looking for other peoples feedback as well on their experience with the modes on the new skylaser you have! :beer:

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

Well, I wasn't exactly looking at the spot up close when measuring. I never do that no matter the power level. The sides of the heatsink were shielding me from directly viewing the spot, and I kept an arm's length away.

40mW of IR is just as dangerous as 40mW of any other wavelength, so if you wouldn't do it with blue/red/green/etc, don't do it with IR. If you know your goggles don't protect you from it, then remember you're basically not wearing goggles. That all said I wasn't too concerned because I never looked at the spot. If you notice in the picture it's all hands free for a reason. I make it a point not to use a laser before I LPM it.

There is no documentation saying the following is correct, but it is a rough guide that I use:
-If the surface is more than 10ft away and nonreflective and of a color that absorbs more than 85% of the wavelength then it is safe to look at the dot for short periods of time if it is under 100mW when not wearing goggles. Inverse quare law applies - double the distance and you can 4x the power level and be safe; 20ft out on same surface as above a 400mW is safe to look at for a short period. The target is the main attenuation factor here, if it reflects the wavelength too much it becomes dangerous.
-If the surface is white or does not absorb most of the light at that wavelegnth then 50mW should not be exceeded (at a distance of 10ft).
-At under 50mW it would take a specular reflection, direct hit, or viewing a dot from an absurdly close distance (<3ft) to cause damage.

So, 40mW of IR on a black matte surface designed to absorb as much light as possible; not an issue if you're >3ft out and not staring at it.

Now, if it were putting out ~100mW of IR, I'd be concerned. I would not expect that much IR from a <400mW green, and certainly not expec it if the green was quite bright as efficiencies are low. Yes there is some risk when you have no idea what the output will be, but that is when you exercise extreme caution.

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

I didn't realize that you weren't looking at the spot while taking the readings and that your view of the dot was also blocked by the heatsink. That makes much more sense now!

Thank you very very much. That was immensely helpful! I think I will copy and save that to my desktop as that was some really good information to go by related to safety of distance and inverse square, reflectivity, mW power etc. In fact it would make a great sticky for newcomers wondering about safe distances etc.

I really appreciate the time you have taken yet again to give me some excellent pointers. I wish I could + rep you, I will be sure to do so when it lets me again. Thanks Sigurthr! :wave:

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

Sigurthr,

Good review.

For your information, you take measurements at 9 - 15cm distnace from the sensor, not less than that (as you did).

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

Nice review! +1

A thing to note is that if you would've liked the laser to be IR filtered, they would've installed it if you had left a note with your order or contacted them.
They've done so with all three of the 532nm lasers I've received from them.

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

Expecting my 300mW "ir filtered" one this week i will do a full review on it for comparison!

Greetings,,

Re: Review: SKYlasers (laserbtb.com) 100mW 16340 532nm Laser

snoutke said:

Sigurthr,

Good review.

For your information, you take measurements at 9 - 15cm distnace from the sensor, not less than that (as you did).

Click to expand...

I have tested my LPM's accuracy with different distances between the laser aperture and the sensor using two of my continuous duty lasers that have stable output with less than 1mW ripple and found that the distance does not matter between 1cm and 1meter. The instructions for the LaserBee A suggest a 6 to 12 inch distance, btw.

Still, I cannot determine the physics behind why distance should matter so long as the entire spot falls on the sensor. Inverse Squared rule does not apply to laser beams, only their diffuse reflections. Unless the divergence of the laser was so large that you would be clipping the spot, there should be no measurable difference between at aperture and a foot away. The slight attenuation by the air would be immesurable for visible wavelengths. Jerry himself has told me there should be no difference in readings no matter where the spot is, as long as it is entirely on the sensor.

AMN said:

Nice review! +1

A thing to note is that if you would've liked the laser to be IR filtered, they would've installed it if you had left a note with your order or contacted them.
They've done so with all three of the 532nm lasers I've received from them.

Click to expand...

Ah man, I had NO idea you could request it to be IR filtered. I had no idea it wasn't IR filtered to begin with, lol. It doesn't say anything about IR filtration on the web page.

Not a real problem though, I can handle filter installation if need be and there in't really much of a need. I don't burn things (... with non CO2 lasers) so to use my earlier analogy... the bullet is only slightly sharper than if it were filtered.

Thank you for mentioning the IR filter option on these lasers - the website does not mention them. I just ordered a 200mW green from laserbtb.com a week ago, I emailed them this morning inquiring about the IR filter, Allen replied and said it is not too late to add one.