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Mini-Review: DX's Romisen 30mW Laser

knimrod

knimrod

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A few weeks ago I ordered the Romisen 30mW from DX and another 50mW CR2 from KD.  They both arrived yesterday.  The KD was DOA.  The Romisen was a very nice surprise in contrast to the huge disappointment from KD.  

There was no battery included but I had a freshly charged 3V RCR123 ready.  After installing the battery and clicking the switch I got a nice green beam exiting the aperture about 15-20 degrees off-axis from the body!  I disassembled the unit but wasn't able to find anything that was obviously out of whack.  After I reassembled it and tried it again, the beam seemed perfectly parallel with the body... I obviously fixed something but have no idea what.

This unit is small and lightweight.  The fit and finish is excellent.  Even the various interior components seem well thought out and were of good quality and workmanship.  While I haven't seen any claims of this laser being waterproof, it certainly appears to be with O-rings in all the right places.  I'll trust that it's at least water resistant though I don't intend on testing its watertight credentials anytime soon.  The on/off switch in the tail cap is a click-on/click-off type with a glow in the dark cap.  The switch has a very nice tactile feel.

Initial power measurement at turn on was 33mW dropping off to about 31mW after ~10 seconds where it seemed to stabilize.  I noticed a lot of noise around the projected spot and at the glass aperture. I disassembled it once more and cleaned the aperture glass.  This cleaned up the beam nicely and resulted in a net 5mW increase in power. :)  

I was able to measure about 6mW of IR using exposed film as a filter.

Current draw was 258mA from a fresh 3.0V RCR123.  With a freshly recharged 3.6V RCR123, current draw was............258mA!  The power output of course remained the same.  This unit actually seems to have decent current regulation so it should handle the 3.6V RCR123s no problem.  

There is a pot inside begging for some attention but for the moment, I'll ignore its call and enjoy what is probably one of the the nicest lasers DX sells.
 

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Very nice.. :) Did you measure the output without the glass?
 
I've had this laser for about a week now and its completely waterproof. I took a shower with it :P

The green module was so off centre when i received it that there was no beam coming out. But it was only a matter of holding it straight while I screwed the head back on to fix this.

Btw knimrod, does yours burn? Mine smokes tape but only with a lens.
 
Current draw was 258mA from a fresh 3.0V RCR123. With a freshly recharged 3.6V RCR123, current draw was............258mA! The power output of course remained the same. This unit actually seems to have decent current regulation so it should handle the 3.6V RCR123s no problem.
Click to expand...

This is very good news - finally a model where they got the regulation circuit right ::) For that reason alone i'd consider buying it...

If you decide to muck with the pot, i'd be very interested in the results... if it does anything at all (in many dx lasers it actually doesnt).
 
it seems DX has been great with the lasers lately, just tested a DX true30 that came in for a friend, peaks at 42 mW :D
 
I measured the output power without the glass. Sure enough, there was another net gain of 3-4 mW.  Up to 38-39mW now.

It's not all good news however.  I think I found the Achilles heel of this laser.  When attempting some burning experiments on a small piece of black rubber sheet I keep handy, I noticed the reflection on the wall from the magnifying glass I was using .  The beam is apparently not TEM00.  It burns great and seemed to have good divergence characteristics but it's not a nicely shaped TEM00 beam.  It may be TEM01 but the beam doesn't really appear as two distinct spots. It's more of a rectangular shaped beam composed of two overlapping spots.  It also doesn't seem to affect divergence very much as the projected spot on a distant object is still fairly small and comparable to my other green pointers.  However, the beam diameter at the aperture is noticeably larger and much easier to focus with a convex lens to a burning spot than my other green pointers.

I decided to go ahead and experiment some more and rigged the module up for use with my lab power supply.  The current regulation is indeed good at 258mA from 3V to 6V. 6V is as far as I went because the temperature of the driver board was starting to rise.    

On to the pot...  The pot does work for controlling power/current.  I noted that the mode shifted back to a more pure TEM00 below 200mA which was about 16mW (no glass).  Just above 200mA, the mode changes back to TEM01(?) and the power jumps to 22mW.  Adjusting the pot up to 311mA resulted in 54mW of output, still TEM01(?).  There was room for more but I stopped there.  

I'll try and get some pictures of the expanded spot showing the mode.
 
Here's the picture of the expanded spot:
 

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hmm that stinks, but strange in how little it is mode hopping, usually when people complain of mode hopping the dot becomes enormous
 
Any mode hopping is undesirable but it doesn't look that bad. I knew you would get a few more mw's out of it without the glass..a 10% gain is nice. From your review and pocketfluff's comments, this looks like a good deal.
 
The modehopping is a bit of a bummer indeed, although i wouldn't be sure that each individual unit will have this problem. Btw, is this problem temperature related?

As for the power levels: around 50 mW at 300 mA doesnt seem bad at all. I'm not sure about the pump diode ratings for these, but 300 mA is about the current most other DX pointers work well at - and they survive. Getting 50 mW out at this current level means that the DPSSD process is pretty efficient overall.

Lets see if i can get my hands on one.. seems backordered for now and i expect little to change there with the chinese new year and all.
 
Who knows. I just ordered the one I posted, and will do an unboxing video and review once it arrives (yay for my kenometer!).
 
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