Miloš Custom Blu-Ray 25mW Laser

I'd like to start this review by saying that I've been very impressed by this laser and will try not to sound too much like a fanboy here...

The sale: Milos had listed these lasers for sale on this forum and his price was well within my budget for the last colour I wanted to complete my laser spectrum... the elusive Blu-Ray. Dealing with him was great, he really knows his stuff and was more than willing to talk tech about the improvements he had made after his last batch. I felt confident that I would get a good product and I was not disappointed.

Shipping: Today I received a nice big, very well protected package. (With the sudden laser-hysteria here in Canada, I was glad to get it at all.) In the package were the following items:

- The laser itself, safely wrapped in fine bubble-wrap in it's own box, with a lanyard
- A Ziplock bag containing the users guide, a spare lens, spring and extra 9V battery
- A heavy little gift-box containing a fascinating "Big Apple" New York hologram crystal. ( Really cool and 3D in real life)
- A neat little incense holder and incense sticks (Milos takes great beam shots, incense is the secret... :-X)
- A freaky little glow-in-the-dark rubber cobra. (!) Great for displaying Blu-Ray florescence!

Review: Better than I could have possibly expected. I paid for a 15mW Blu-Ray, but I was lucky to get one of the freaky-good diodes Milos had found in his last batch and when I tested it with my trusty Kenometer, the thing is putting out 25mW+! It has yet to drop below 26mW and I've been testing it for 30 min. so far. 9V batteries rock!

The case is really interesting and the fabrication is very clean and precise. A really professional build IMO. Nothing's loose, nothing moves unless it should and everything works perfectly. Good quality work. This laser turns on with an indented rheostat, which actually provides lower power levels in several steps, as opposed to a linear reduction. Milos has built in reverse polarity protection which is always a plus on any device using 9V cells, and changing the battery is a breeze, with no unscrewing required. I actually really like the case, it's small, fits the hand nicely and unlike most of my other lasers, it doesn't roll.

The dot is much more visible than I expected and even the beam is visible with a bit of incense in the air (in the dark, of course). The beam is fairly fat, about 4mm, but that can easily be remedied with the same lens combination I use to reduce my Pulsar's beam if I need to reduce it for dichro combinations. I have yet to try the focus ability, but I see no reason it won't work. Right now the beam is nicely collimated, with little noticeable divergence at 10m, so I'm leaving it alone. This is such a unique colour, a vivid shade of violet that dances on the edge of visibility. Quite beautiful actually.

To show the laser in action, I've posted a video review on YouTube showing the meter output and the case, etc. here: http://www.youtube.com/watch?v=s-k6FYn8mq8

All in all, I give two thumbs up [smiley=thumbup.gif] [smiley=thumbup.gif] to Milos for an impressive piece of work and for great customer service. I would definitely do business with him again.

Re: Milos Custom Blu-Ray 25mW Laser

Very nice blu. You got real lucky with the output on that one. I hope you get many hours of use from it.

Re: Milos Custom Blu-Ray 25mW Laser

Wow, I was considering buying one of these, but bought a Kenom barrel red from drlava instead. I gotta say, I'm really impressed with the review video, made it look really great.

Re: Milos Custom Blu-Ray 25mW Laser

Hi guys,
Thanks for the review CC, WOw, I'm on Youtube )) By the way the second pronunciation in video of my name is correct (just with shh instead of just s)

I am very skeptical about it outputting over 25mW I must say. I measured it many times for 2-3 days with different batteries and it always showed me 15.5-16.5 Peaks. This has to be something to do with testing procedures. More than anything because if it was 28mW all the time it would not make it for 30min or even 3 probably. I will contact Ken over this issue as I want to o buy his test meter this week too.

Anyhow, let me know if you have any questions.

cheers

Re: Milos Custom Blu-Ray 25mW Laser

Yeah, I was pretty surprised as well. I know there has been some discussion about thermal head meters such as Kenom's and their sensitivity at different wavelengths, but I would think that the further from IR, the less sensitive it would be. (Please one of our more scientifically astute members set me straight if this is incorrect) The meter is pretty consistent with the output certificates I have for my Vega and RPL, so I'm sure it's pretty accurate. (±5mW) I also just tested it for 2 min. at at time, not for 30min. straight. Didin't mean to mislead there.

I guess this raises a good question. Is there a curve of sensitivity vs. wavelength for a thermal power meter? This would be a good thing to know considering how many of us have bought or built such meters recently. Hopefully someone here has the equipment and the wherewithal to come up with a good testing protocol and we can get a definitive answer.

Cheers, CC

P.S. Sorry for missing the first "shh" Milos!

Re: Milos Custom Blu-Ray 25mW Laser

OK, lets see if I can address some of the questions with the limited knowledge I have concerning the meter.  I was told by lava, when he reverse engineered the boards that they were initially designed for high output lasers.  upwards to possibly 10 watts.  He indicated that the meter probably wouldn't be very accurate for 405nm or at least anything below 10mw.  Now, I shipped on of the boards to pseudo and according to his tests it came out fine for that wavelength.  I personally don't have any other meter than the one I'm using to personally test the accuracy of each of these meters.  I do compare them to the meter I had tested by pseudo to make sure they are reading the same output on the lasers I do have here. (50mw green, 250mw 660nm)  so, the only thing I can say is ship the laser to dr. lava along with the meter and have him check both the meter and the laser against his coherent fieldmaster I'll even pay for shipping there. (only one way though)

Re: Milos Custom Blu-Ray 25mW Laser

Another solution would be to ask around here if anyone has both kinds of meters (ie; Coherent and any Thermal) and see if they have ever compared them at 405nm. I'd prefer not to ship my stuff anywhere now that the laser-scare has heightened awareness at Customs here, but if anyone has a Lasercheck or FieldMaster here in Southern Ontario I will gladly meet them to do a side by side test and report the findings to the forum. In fact I'll bring all 5 wavelengths I have and see if we can't come up with variance values for each one. That would be some handy data.

Cheers, CC

Re: Milos Custom Blu-Ray 25mW Laser

I'm sure this will be resolved soon. I would love to own one of these meters if they can do 405nm -/+10-15% accuracy so I can double-check and reference tests with my coherent laser check.

cheers.

Re: Milos Custom Blu-Ray 25mW Laser

Hey, nice. What current is the idode running at?

Re: Milos Custom Blu-Ray 25mW Laser

Hi Doc!

I was searching your posts over at PL where you were testing 405nm diodes in a thread by Kaz. He seemed to indicate there that his Lasercheck and Die4Thing thermal meter seemed to agree on the power at this wavelength. It was the only thread I could find that referenced 405nm and Power meter, but it has my hopes up that I've really got a winner laser here. (Thanks entirely to Milos of course)

In your vast and respected opinion regarding these diodes, could it be possible? Milos has said that he actually underpowered this diode for longevity. I think he said 40mA. Could that give anything near the 26mW+ I measured with Ken's thermal meter?

I really appreciate your opinion on this.

Cheers, CC

Re: Milos Custom Blu-Ray 25mW Laser

I set your laser at 41-42mA. You can check your tech sheet. I don't cross 42mA, and only one other diode outputed 16mW at that current. Usually they are around 8-12mW at that current.

Re: Milos Custom Blu-Ray 25mW Laser

So I wonder what on earth is making it read so high on the thermal meter? :-? The Coherent uses a photocell, so it's just measuring photon hits, right? I've measured it at distance and close up, always with the meter stable at room temp holding zero and it repeatedly measures 27-28mW at first then slowly drops to hold at 26mW. (The longest I've kept it on was the time I made the video review, because frankly, I want it to last a while). I've repeated this about 10 times now and it's very consistent. The meter seems to be bang on for my RPL-Blue, confirming the readings Jack took when he sold it to me a month ago, so I'd say it's accurate at 473nm. One would assume that 70 less nm would not introduce such a large margin of error. Very puzzling, wot?

I have every confidence that the laser is indeed set at 42mA and I can't think of any way that could change in shipping, I mean the pot is hot glued and sealed. (Even signed and marked as 42mA) I've done as much as I can to make the test as valid as I can here, so there must be some explanation...

CC

Re: Milos Custom Blu-Ray 25mW Laser

Curiously_Coherent said:

Is there a curve of sensitivity vs. wavelength for a thermal power meter?

Click to expand...

Yep! But its not as pronounced as with a silicon sensor. The sensitivity is based on the coating. Normally the absorbance of the coating is very stable across a range of wavelengths - IE across the visible range I think my sensor only has a variation of couple of percent at most (and I can set my meter to compensate for it). However once you get outside of that range there can be some significant changes since there's no coating that can be equally absorbent over a large bandwidth.

But yeah, that meter probably wasn't made to be that accurate at such low ranges. When I tried ~10mW 405nm across my power meter, it jived well with Ken's but that could have just been a crapshoot. A sensor made for high power lasers ain't gunna be doing too well with a few mWs. :-/

Re: Milos Custom Blu-Ray 25mW Laser

Thanks for the input Pseudo! I guess that leaves me with a quandry then... Here's the problem:

Once stabilized to room temperature and holding zero, this meter does seem to be accurate even at small mW values. (ie; My Core and Vega are both stable at 4-5mW, and the DX30 and KD 50 readings make sense as well. (See my review of the Kenometer for all my lasers' values here http://www.laserpointerforums.com/forums/YaBB.pl?num=1204695371 ) However, I can see that 405nm might be out of the coating's "range" as you have suggested. Any idea what the meter might be registering then? 405nm diodes don't put out IR (I believe), so it has to be registering energy of some kind. If not then that's a pretty big margin of error specifically at that wavelength.

Would that mean then that a Lasercheck (or better) is the only reliable testing method for a 405mW laser? (I'm not disappointed with my Kenometer, I love it, but I'd rather not be posting erroneous readings for 405nm, understandably)

Still puzzled... so I'm going to do a vid tomorrow showing the readings from my Core, Vega, RPL and BluRay one after the other so you can see what I mean. Inquiring minds need to know!

Cheers, CC

Re: Milos Custom Blu-Ray 25mW Laser

Hi, 42mA seems safe in my experience (for pointer use lasers). At 40 mA, I see a 'settling in' loss of 1mW after 24 hours burn and less per day after that for the good PS3 diodes, under constant current regulation.

There are only two explanations:
1) the laser is actually putting out more than 16mW now (possible, depending on the driver config, as the Vd sags with use)
2) The meter absorptive surface is less efficient at 532 and 660nm, and absorbs more power (less reflective) at 405nm.

2 is only possible if the thermal meter coating surface on your unit differs significantly from the ones pseudo and I tested.

You can measure the approximate current draw from the battery with a multimeter and alligator clips. It will be slightly higher than the diode current, Milos can tell you how much higher.

Re: Milos Custom Blu-Ray 25mW Laser

The sensor head used in Kenom's meter and in the DIY meter looks typical of Coherent's broadband thermopile coating.  It's supposed to be spectrally flat from 190-11,000nm.  Coherent does offer a different coating for excimer lasers with a flat response from 150-1000nm.  All my DIY probes track with my Coherent 210 probe at 405nm.

For what it's worth, I've received 2 different type of sensor heads with the surplus PCB assemblies.  One type has disc with a coating that's a slightly lighter color than the other.  It also has 8 screws securing the disc instead of 6.  There doesn't seem to be any perceptible difference in the response though.