Topic: Proper way to setup a 532nm DPSS for Analog Modulation

[Alfa Romeo]

I am building a .5w 532nm DPSS from the setup attached. my question is, to get descent analog modulation from a dpss what should the ONE PIECE ND:YVO4+KTP CRYSTAL temp be set at. with seperate crystals, the ND:YVO4 should be cooled and the KTP should be heated i think. but with a one piece unit, is there a 'rule of thumb'. any comments appreciated.

assuming double TEC, 1 for the IR diode,  1 for ND:YVO4+KTP CRYSTAL.

tia
Pat


specs from seller:

LASER CRYSTAL, LASER DIODE, CAVITY AND LENS OPTICAL ASSEMBLY

 

    * COMES WITH A NEW THOR-LABS 300mW T0-18 808nm C/W LASER DIODE.
    * COMES WITH A ONE PIECE ND:YVO4+KTP CRYSTAL
    * COMES WITH ALL THE AR COATED GLASS OPTICS NEEDED.
    * WILL HANDLE UP TO 2 WATTS OF 808nm PUMP POWER. FIT A 1 WATT DIODE AND YOU WILL HAVE SOME SERIOUS GREEN POWER FROM IT BECAUSE OF THE TWO SET GRIN LENS ASSEMBLY THIS UNIT HAS AN EXTREMELY HIGH CONVERSION RATE FROM 808nm TO 1064nm TO 532nm.
    * THESE UNITS ARE EASILY CAPABLE OF PRODUCING 600mW OF 532nm GREEN, I HAVE DONE IT! I PRODUCED 624mW AT 532nm C/W AT A VERY PRECISION LOW DIVERGANCE ROUND BEAM.
    * COMES WITH ALL HIGH QUALITY GLASS AR 808nm AND 532nm COATED GRIN LENSES AND 532nM COLLIMATING LENS AND ALSO A FINAL FOCUS LENS.
    * THIS IS A ALL THREADED ASSEMBLY. NO CHEAP PRESSED TOGETHER, PRESS FIT LOW QUALITY PARTS HERE.
    * EVERYTHING IS ADJUSTABLE, DIODE ROTATION, DIODE DISTANCE TO GRIN LENS- GRIN LENES ARE ADJUSTABLE IN DISTANCE TO AND FROM THE CRYSTAL AND TO AND FROM THE LASER DIODE ITS SELF AND ALSO IN ROTATION, THE COLLIMATING LENS IS ADJUSTABLE IN DISTANCE FROM THE CRYSTAL AND IN ROTATION WHICH IS WHAT IS REQUIRED TO ACHIEVE MAX OUTPUT POWER.
    * THE ROUND OUTSIDE DIAMETER MAKES IT EASY TO MOUNT INTO A TEC COOLED HEATSINK BLOCK, JUST DRILL A HOLE IN A PIECE OF ALUMINIUM AND TEC COOL IT OR FAN COOL IT AND YOU ARE DONE, ALL THE HARD WORK HAS BEEN DONE ALREADY,
    * PERFECT FOR LASER BUILDERS OR HOBBYISTS, EXTREMELY SIMPLE ASSY.
    * SIMPLE, 808nm IN AND 532nm OUT.[/size]

[James]

With parts as small as that, how do you plan to do it?

Don't those pieces have to be very close together?

Please keep us informed about this project and take pictures!

This looks really interesting.

James. 

[Fanny Pack]

I have no idea what to do with the temperature but I would assume you would be able to adjust it and find the sweet spot once you get it working.

500mw seems pretty agressive.  My 50mw has a 0.5W diode in it I think.  If it scales then you would need a 5W 808nm diode which is over double what the kit says it is rated for.

Good luck.  Keep us posted.

[Alfa Romeo]

I just got it in the mail today. its assembled as one module all screwed together except for the final lens. have not disassembled yet. waiting till its in the TEC cooler. guess i'll whip that out first, then it will fit in to the old greens location. i will ask the seller which diode was used to get the 600mw. it does look small!

pat

[Fanny Pack]

How big is it?  It looks itty bitty.  What sort of diode does it use?  Not a C-mount apparently.

[James]

Here a thought...

Thermal zones!

You could put thin pieces of fiberglass between the plates and bolt them together with nylon.

James. 

[meandean]

  What kind of electronics are most commonly used to drive laser diodes?

[James]

A diode is a diode!

The voltage drop across them is a matter of chemistry.

They are current sensitive devices.

A diode driver is something that can regulate current.

James. 

[meandean]

 I'm looking for a little more info, dude!

[James]

There are some schemos around here and there...

Ask drlava. He designed the flexmod.

Take a look at what dtewksbury just posted a few days ago.

James. 

[Alfa Romeo]

The module was shipped with a 5.6mm diode ir 808nm stated as a thorlabs 300mw. thorlabs only has a 200mw 5.6mm diode. no biggie, used just for testing. notice the crystal is one piece and descent size

A 2w 9mm diode should throttle this to around 500mw do you think??

found as shipped the modulation sucked, when cooled to just above dew point. but when warmed, the change was much better. ok so then cool the diode and warm the crystal.

so remount the brass holder for the crystal and thermally isolate it with?
James mentions fiberglass, examples? thickness? i will need to remove equal amount of brass from mounting point to maintain focal point of the pump entering into crystal.

Notch the brass end piece to allow access to the crystal for temperature control. Remove threads and use set screws to allow slipon over crystal and crystal heater wires. maybe just a power resistor for a little heat and a temp monitor for closed loop control. any thoughts.

here is a shot of the components and layout. and a shot of adjusting the crystal holder in center of pump beam.

I will get a 2w 9mm pump diode for more power, mean while  add temp control for crystal holder

here is a thought, do not use the brass end piece, and mount the collimation lens to base plate with the final focus lens. this allows open access to crystal holder for temp mon/control.


later
pat

[James]

Dude!

I gotta' tell ya'........

You take some tasty pictures!

This is really inspirational stuff.

You are one-of-a-kind !!! 

I'm so glad you post here! 

Thanks for the images!

James.   

[dtewksbury]

Alfa Romeo, I don't mean to be picky, but wouldn't your dichros work better at 45 degrees, or is that photo deceptive.

Just thought they may not be passing as much as they could, or reflecting as much as they should for that matter.

It's just that I have found the angle of incidence seems to have a large effect on the pass bands.

[Fanny Pack]

I have found that dichros have better pass through if they are more perpendicular to the beam than 45deg.  Reflection doesn't make much difference.  I did some testing and I was able to get 10-15% improvement from rotating my dichros from 45deg to around 30.  At least this is the case with laserwave dichros.  I have some Edmunds dichros but have not tested those although I expect the same, to some degree.

[dtewksbury]

OK fair enough.