Review of 70 mw DPSS blue from Dragon Lasers

[buffo]

Hi foks;

As promised, here's the review of that 70 mw DPSS blue laser that I tested from Dragon Lasers. (Scroll to page two of that link for the exact laser I reviewed.)

Since I've been accused several times of being waaaaay too long-winded, I decided to type up a short review (with pictures) first, and then attach a text file with the long version of the review to the end of this post. All the pics in this post are hosted in my gallery right here on PhotonLexicon. (Note: I also put together a short video showing the laser in operation. It's available on Cruch's FTP server and also on Google Video.)

Dragon Lasers is a reseller/distributor of CNI lasers. The one they sent me had TTL blanking only. The shipping was *fast* (6 days), and the packaging was superb. Everything was very well protected.

Here's a picture of the head right after I unpacked it:


Here's what the driver board looks like. Check out that heat sink! The blanking leads are still bundled together...


This shot should give you some idea of scale. If you look very carefully you can just barely see the beam. This was taken in a brightly lit room, in clean air, with the flash on.


This picture shows the beam with a tiny amount of fog in the air. (No flash, but still a bright room.)


Now to the important part: How did it perform?

Right out of the box the unit was making over its rated power. (I measured 75.6 mw.) Then I let the unit run for 105 hours to burn it in. Power remained stable throughout the burn-in period, and the laser head stayed cool. The driver board did get lukewarm, but never got hot. (There is a small, silent fan on the bottom of the heat sink for the driver board that keeps everything cool.)

I tested the blanking using a variety of ilda frames, looking for any signs of blanking-induced power loss (so called "jellybeaning"), but could not see any evidence of this.

I measured the beam diameter at the output of the laser. It was very small; between 1.3 and 1.5 mm. (It's hard for my eyes to measure things that small!)

I set the laser up outside and checked the beam divergence at 105 ft (which is 32.004 meters) away from the head. The beam spot at that distance was 24 mm, which works out to .7 mrad divergence. As you can see in the composite picture below, this compares favorably with some of the other lasers I own:



In fact, the only two lasers that had smaller beam diameters at that distance were my lasever DPSS blue and my Lasever DPSS green. But note that both those lasers have larger beam diameters as they exit the head. (2 mm for the Lasever green laser, and just over 3 mm for the Lasever blue.) I think the Dragon Laser unit is set up for minimum beam diameter at the aperature; of course the trade-off is that it has slightly higher divergence than the Lasever units. (The best divergence of the bunch was only .5 mrad, which was the Lasever blue.) Personally, I think they made the right choice.

Summary:
I'm very impressed with this laser. Blanking speed is excellent, beam quality is excellent, power stability is excellent, and thermal management is excellent. The head is rugged, and comes with a thick baseplate that makes it easy to mount and also serves as a good heat sink. The packaging of the laser is superb; I honestly believe I could have drop-kicked this thing across the room and it would have survived unscathed, so long as it was still in it's original packaging. (No, I didn't actually attempt this!)

Another plus is that everyone I've been in contact with at Dragon Lasers has replied to my e-mails with amazing speed. (Longest wait for an answer has been 36 hours, and that was over a weekend! Average response time is less than 10 hours.) Furthermore, everyone speaks (and writes) *fluent* English. (Absolutely no language barrier here!)

At the end of the review period I was offered the opportunity to purchase this laser at a discounted price, but I declined for two reasons: 1) It only supported TTL blanking, and I prefer analog. 2) It is rated at 70 mw, and I already have a 100 mw blue. I wanted more power.

Dragon Lasers sells blue DPSS lasers (with analog or TTL blanking) up to 7 watts of power. They also sell DPSS green lasers, DPSS red lasers, and direct injection red lasers at both 635 nm and 660 nm.

Now, for those of you who are *really* curious, you'll find the text of my complete review attached to the bottom of this message. The full review text includes a more detailed explanation of the test methods and some extra measurements that were taken. It's also got more of my personal thoughts about the laser and the company.

Adam

PS: More pics of this laser can be found in my gallery.

[dave]

Nice review Adam,

As i keep saying, CNI lasers are leaps and bounds ahead of other Chinese lasers.

[The_Doctor]

Looks good. I didn't feel any temptation before because there enough things to put me off, but this would meet what I want from one. How much do they want though? I know I haven't got it right now but that could change.

[Zoof]

Great tests! Do you have some pics of scanned images you can post?

[buffo]

Doc;

The quoted price on the laser I reviewed (with TTL modulation) is $800. I don't have a price on their 70 mw laser with analog modulation, but I do know that for 100 mw of 473 nm blue w/ analog blanking they charge $1500. (And just for the curious, 200 mw of 473 nm w/ analog will run you $2400, while $250 mw is $3200.)

Zoof: I don't have any pictures of the scans, but there is a video that I made that shows some scans. (Mostly test patterns, but some abstracts as well.) It's on Cruch's FTP server, or you can grab it off Google Video here. (Link is direct to the video.)

And Dave, you are absolutely right. These CNI lasers are certainly a cut above the rest. Granted, they're more expensive, but they're built like tanks with excellent power and thermal stability. Plus the beam was very near to being perfectly parallel with the baseplate. (In contrast, my Lasever blue has a beam that points down at 8 to 9 degrees! That makes alignment harder...)

BTW, the guy I was working with (Frank) is a member here on PhotonLexicon. He's been keeping a low profile, but I'll see if I can flush him out of the woodwork to say a word or two...

Adam

[dave]

I gotta chine in here,

http://lasershowparts.com/store/inde...ewCat&catId=22

Our prices are considerably cheaper, and all our lasers are analogue.

[buffo]

Dave;

You're right - your price on the 100 mw CNI blue w/ analog is quite a bit cheaper than Dragon Lasers. (Nearly $470 less!)

Most of your other prices are quite close to theirs though - at least the one's that I've researched. (I do have a partial price list from Dragon Lasers; I've been comparing it to the other CNI dealers...)

Adam

[aijii]

Right out of the box the unit was making over its rated power. (I measured 75.6 mw)

Buffo, I am little concerned at this - firstly to the extent of our knowledge, CNI does not manufacture 70mw blue DPSS lasers - they make 50's, 80's and 100's....

Secondly, when we buy (and sell) a CNI laser rated at say, 200mw from CNI, we regularly meter it at doing in China doing well in excess of this, sometimes over 300mw.

Your laser is barely making 70mw.

Therefore, I suspect you've been sold a 50mw laser as a 70mw. But the laser is doing 75mw right ? so whats the problem ?

Well, CNI rate their lasers conservatively for a reason. It probably won't be doing 70mw at the end of it's warranty period - just keep your eye on it. If i am correct, the box-dropper has made a lot of money by buying a 50mw laser at cost, and calling it a 70mw and charging you for it.

We know this is a regular practice with Chinese CNI resellers, as we've been a victim of it ourselves on multiple occasions with one rather well known Chinese reseller. We thought we were getting a great deal, until we noticed that lasers we bought direct from CNI were making significantly higher powers than similarly rated ones from this un-named reseller.

As a note - we do not engage in this practice ourselves. We meter all lasers before they ship and if we do not believe the laser is making enough power for it's rating we shoot a rocket up the ass of the particular manufacturer.

Anyway - excellent review overall Buffo

Cheers,

aij-

[aijii]

http://photonlexicon.com/gallery/dlr...SCF0806?full=1

I just had a look at the picture, and it looks even worse than I suspected.

Thats a 20mw laser! Clearly from looking at the label on top of the laser... "MBL20"

So they wanted $USD800 for a 70mw laser that really was a 20mw laser that happened to be making 75mw and was very stable and well built...

Clearly that says a lot of positive things for the manufactuer, sadly not the same for the reseller though.

[buffo]

Hi Aijii;

You know, your partner Dave also mentioned that sticker earlier. When I unpacked the laser and saw that, I simply assumed that they just put the wrong sticker on it. (There was some initial confusion when they sent the laser to me for review; the order had been keyed in wrong, so they e-mailed me to clarify.)

I will also admit that the thought crossed my mind that maybe they had hand-picked a winner for me to review, but I dismissed that possibility based on their communications. (Plus it seemed unlikely that a laser that was only rated for 20 mw could ever make 75 mw, even if it had been cherry-picked for the review...)

Hmmm. I wasn't aware that CNI had problems with power fall off later in life. I've only put about 112 hours total on this laser with all my tests. At what point does the power usually start to drop, based on your experience?

We meter all lasers before they ship and if we do not believe the laser is making enough power for it's rating we shoot a rocket up the ass of the particular manufacturer.

YOW! I'll bet that hurts! But I see your point... No one wants to get a reputation for selling lasers that malfunction only after someone has spent hours and hours mounting the damn thing in a projector. (Hmmm, I can think of a couple other brands that fall into that category...)

What do you consider an adequate power margin for a CNI? 20%? 30% If you have a laser that is rated for 100 mw, what do you normally look for in terms of power output before you say it's good?

Adam