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FrozenGate by Avery

200mW of green for $125 shipped!!!!!!!!!!!!!

paulzimm said:
I used my new +150mW mini-lab green laser in my custom built projector, check it out:
YouTube - Laser Projector
Click to expand...

Get some red in there ASAP!
edit, I just watched your other videos and saw you already have red. What are the heatsinks you're using for the diode lasers?

Also, how's the analog modulation with yours? Is it smooth and relatively linear to the modulation voltage?
 
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Yeah, I have since added a red to the projector:
YouTube - 2 Watt RGB Laser Projector

I still have one more LOC red (for a total of 2 at 500mW combined) but I am waiting on the PBS optics to be delivered. Compared to the red/blue lasers using the FlewModP3 drivers, the 150mW analog modulated green isn't nearly as good. When doing shows the beam is sometimes "dotted" instead of dimmed. I may one day replace the power supply for the green but for now it is good enough.
 
I think to get a good linear modulation response from green, due to the non-linear nature of the beast, would take a specialized power supply, since driving the pump at 50%, for instance, would seldom yield 50% of the green output.
 
Speaking of analog modulation- could someone take some measurements for me? Quite a few of you seem to have the analog version of these labbies.

I'd like to know what the minimum modulation current is at 5V, if anyone could do that.

Thanks in advance
 
Surely this can be corrected in software or via a colour correction board?
 
dnar said:
Surely this can be corrected in software or via a colour correction board?
Click to expand...

Problem is, it's not linear, or logarithmic.

Think linear, and with irregular steps every now and again. You'd have a lot of programming to do.
 
goninanbl00d said:
Problem is, it's not linear, or logarithmic.

Think linear, and with irregular steps every now and again. You'd have a lot of programming to do.
Click to expand...
Oh, that does not sound good..... Perhaps a modification is in order or replace the laser drive altogether and just keep the PSU for the TEC and laser power source?
 
That won't change things. The problem isn't the power supply. The problem is *what* it's driving. A linear power increase to the pump diode (on any DPSS, not specifically these) won't yield a linear output on the green like it would on a diode. If your using projection software that uses a fixed color pallet, you could probably adjust the levels for each color in the software so they would display correctly. However doing it in the laser itself, for every point between 0 and 100%, would be a fairly complicated thing to do, plus it most likely would degrade the lasers response time since every time the power changed, whatever MPU your using to do this would have to do table lookups to figure out how much pump power to put out compared to the modulation input.
 
Judging by the way two of my greens warm up and then jump to full output, it will not be easy to modulate a green fluently.
 
The problem is twofold:

1) The crystals are just a simple MCA, so the TEC is only stabilizing the diode. Most of the mode/power instability in a DPSS laser happens in the crystals so in that regard these and the vast majority of simple, inexpensive lasers will always exhibit some instability.

2) The driver could be lousy quality. I don't have an analog version of this module, but I do have several TTL models. If the driver isn't linear (through crappy engineering), then that would explain the dotted lines and other anomalies as well.

To help determine which is the cause, try feeding the laser TTL signals and see if you still get all of the same symptoms. If things seem generally better when running TTL signals, the driver is the most likely culprit.


Mine do fairly well with TTL, so I think that they should be pretty acceptable in terms of crystal stability, but of course each will be different.
 
A considerable amount of green for ~125.00!

How can they sell these so cheap?

Pump diodes are not very expensive these days, nor the drive electronics. Perhaps some refinements have been made manufacturing the crystal sets which do the magic of converting the pumps 808nm output to 532nm (alien green) ??

Tempted to order one of these tho I'm not certain what I'd do with it :)
 
laser_freak said:
The color correction boards sold on PL only correct for the time delay in modulation of DPSS lasers.
Click to expand...
Ah, thanks, I learn't something new today.

Thinking more about modulation linearity, something came to mind.

What is needed is a modulation driver that includes optical feedback that utilises a PID control loop to obtain the required output. Much like the Galvo control loop.
 
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