Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Suggestion - Diode for holography?

Joined
Dec 27, 2013
Messages
17
Points
0
OK, so I've been playing with my lasers for a while, and burning stuff got old pretty quickly (and the wife doesn't appreciate the stink and the scorch marks around the room either). So I want to try some interesting experiments with lasers, and one of the things that always fascinated me is holography.
I've had a look at all the discussions here (though holography doesn't seem to be a major interest around here) and I've studied a lot of theory.

So now I'm looking for a simple red diode with the following characteristics:
1) Must be able to have an almost infinite duty cycle (it must be able to be left on for many minutes at least);
2) Must be single-mode (no mode hopping, which would ruin any exposure)
3) Decent coherence length (I'd say at least 30 cm, preferably more)
4) Must be significantly over 5mW, but not extra powerful (it shouldn't burn the object being illuminated, and shouldn't be too dangerous for the eyes, especially considering that it wouldn't be focused at all).

I know that for 1) it's more a matter of the heatsink/cooling, but I suppose there are diodes better suited than others.
If I got an inexpensive LPC 826, could I drive it to a very low current until it emits about 50mW? Where is its low mW threshold?
I've also seen several pre-built modules in Odic's shop; these would be convenient because they include the driver. Have you ever tried any of them, and do they meet my needs above?
In general, could I just buy a higher powered module and "pot-mod" it to lower its power, to obtain better duty cycle / "single-mode-ness" / coherence length?

Also, is it possible to find / make a cheap interferometer, to see the "fringes" to estimate the suitability of a laser and setup?

Thanks
Cristian
 





Joined
Dec 11, 2011
Messages
4,364
Points
83
I tried holography with various red and blue wavelength diodes a year or two ago. Even with active temperature controlled heatsinking I couldn't get the output stable enough for holography. You really need a good HeNe and vibration damped optical table to get the job done right.
 
Joined
May 1, 2009
Messages
181
Points
28
two years back I've started with holography and right up from the beginning the results have been quite spectacular :yh: I first started with one of the holo-packs available from INTEGRAF. Super simple...

But the small laser diode was not really promissing (small holograms, long exposure) and I started to build my own diode laser suitable for this purpose.

A really perfect site about this topic is the following one:

Mode Stability of Diode Lasers

I successfully build one based on the HL63133DG laser diode. And even without a proper temperature controller the laser works is suitable (just give some hours to settle and check for mode jumps).

But finally you'll find yourself building a super precise exact temperature controller.
 
Joined
Jan 2, 2008
Messages
1,513
Points
83
Adding to what's already said, Temperature stability I think will be the biggest issue with any diode laser.

As mentioned above super long warm up time for relatively stable control or switching to a HeNe instead, which should give better results. This is just what I have learned after lots of reading.

I would like to give it a try, but finances and other pursuits have moved it lower on the list. Let us know what kind of results you get.

You might also try PL, as they have a section devoted exclusively to Holography.
 
Joined
Dec 27, 2013
Messages
17
Points
0
Thank you for your replies! I've been thinking about getting one of the kits from Integraf or Litiholo (the latter has self-developing plates, and avoiding the chemicals would be a bonus).
Mojo, how do you check reliably for mode hops? I thought the best way would be an interferometer, but they're not trivial to build. I managed to find a beam splitter suitable for 650nm, and I've ordered a couple first surface mirrors.
But as you say, the lasers in the above mentioned kits are too weak, that's why I was looking for something with a bit more power...
 
Joined
Jul 8, 2007
Messages
530
Points
0
I'm able to get perfect transmission holograms using a DIY red laser. It's a Sony 16x DVD diode, 'underclocked', consuming 125mA. The output is ~75mW. No Duty cycle - I leave the laser on for 2 or more hours and start exposing holograms after a 10-15 minute warm up. This gives me a ~1 second exposure, immediately followed by close to 10 minutes of film development.

Here's the laser - it's messy but functional. Lots of brass and thermal glue (Arctic silver here) keep the diode cool and long lived. (Note - the pot is not used, I bypassed once I'd settled on 125mA currect)

Eric'sHologramLaser.jpg


Here's one of my many transmission holograms (> 100). Sphere magnets. A lensless 15mW 635nm laser is bringing this hologram to life.

TransmissionHologram_sphere_magnets.jpg


Supposedly the LM317 protection circuit is very stable with alkaline batteries. I did not have much luck with other regulator circuits. Good luck!
 
Last edited:
Joined
Dec 27, 2013
Messages
17
Points
0
@Flogged, thanks, that's exactly what I had in mind. Do you know the part number of the diode? Or the model number of the Sony burner? I'd rather start with something I know can work, rather than try diodes "blindly".

What's the purpose of the penny and of the straws in your box? :)
 

JimMc

0
Joined
Feb 22, 2014
Messages
19
Points
3
I've used high power single mode red lasers for Holography. Almost any DVD burner diode will work if run at low power and well temperature stabilized. If you are going to all the effort to build a stable table, may as well build an interferometer and test both your diode and your table at the same time.

-Jim
 
Joined
Jul 8, 2007
Messages
530
Points
0
@Flogged, thanks, that's exactly what I had in mind. Do you know the part number of the diode? Or the model number of the Sony burner? I'd rather start with something I know can work, rather than try diodes "blindly".

What's the purpose of the penny and of the straws in your box? :)

I'm not certain about the diode. I purchased two of these diodes from a 'SenKat' here in 2007. There were advertised as Sony 16x DVD diode. I imagine any DVD or single mode diode will do.

The penny was used to raise the switch. I had cut the plastic project box inaccurately. The Q-tip straws are to reduce vibrations. I used solid core copper wire and they vibrated badly enough, when joslting the pointer, that I was worried the delicate magnet wire soldered to the diode legs would sever. It's a hack. At least 30-40 hours on the diode thus far, still functions.
 
Last edited:
Joined
Jan 7, 2007
Messages
6,309
Points
83
Flogged ----
What can I say but NICE -- +1 Dude
I've never seen a holo on LPF.
HMike
 
Joined
Mar 10, 2013
Messages
2,918
Points
113
I use my SP-127 for my holography. but I've done it with a diode, it just needs heavy thermal and optical feedback to control it spot on, so it doesnt have much power flux, and a longer coherence length that doesnt vary.

and something to remove vibrations of course....my buddy has a hollowed out table full of sand, which is what we use as a vibration dampener.
 
Last edited:




Top