Homemade High Power Diode Laser

Solarenemy · Post by **Solarenemy** » Sat Jan 24, 2009 5:58 pm

I realize I am new to Holography but I see a fundamental problem in your play back scheme. For a hologram to be viewed it requires a point source of light. A single point source. Yes a stage light without a color filter is a point source but if you are using multiple stage lighting then your playback is going to blurry if not even visible at all. You have multiple point sources from multiple directions and they will cancel each other out or interfere with each other. The only way to get to really work is to have one single spot light and all other lights turned off. But even then people who are not at the right reference angle will not see the holograms.

koliaco · Post by **koliaco** » Sun Jan 25, 2009 7:21 am

Solarenemy wrote:You have multiple point sources from multiple directions and they will cancel each other out or interfere with each other.

I have thought about this and am planing to do multiple exposure at different angles, have not tried yet, but going to soon.

walschuler · Post by **walschuler** » Sun Jan 25, 2009 2:37 pm

Solarenemy wrote:

koliaco wrote:
Solarenemy wrote:You have multiple point sources from multiple directions and they will cancel each other out or interfere with each other.

With two or more light sources for viewing you will normally get two or multiple images. They may or may not overlap each other depending on how you shot them, thus may appear as intermixed phantoms or separate, which in either case might be an artistic advantage.They will not normally cancel each other out.

I often do double exposures in which I flip the plate or film top for bottom in between shots. That way I get two pairs of real and virtual images, and the real from one shot and the virtual from the other are viewable from each side of the emulsion. When I do that I pay attention to the fact that the object has to be "upside down" in the shot for which I want the real image.

koliaco · Post by **koliaco** » Mon Jan 26, 2009 11:38 am

Just back to questions about building the Diode laser.

Can the aluminum plate be 2-3mm thick or is it important to get it around 6mm (1/4") thick?
Would it be better to use copper plates instead? since its thermal conductivity is about one and half times higher.

What max voltage should the peltier element be able to produce to provide optimum thermal sensitivity?

Would it matter what resistance of NTC thermistor to be used with HTC3000?

Does anyone know where to get a power supply about 9VDC @ 4A as suggested on holowiki?

Jeffrey Weil · Post by **Jeffrey Weil** » Mon Jan 26, 2009 2:47 pm

Hello Everyone,

It looks like that electrical design is just a simple current limited supply. That would work fine but by the time you've got all the parts, soldered it up, fixed the mistakes, etc.....it might just be better to get a simple bench power supply. Something like this.

http://cgi.ebay.com/MASTECH-HY1803D-DC- ... 1|294%3A50

Not only will it run all your diodes and led's but its usefull for so much more. Its also voltage regulated if you choose. I actually have two bench supplies in my lab I use them so much.

If your willing to pay a little more you can get one like this with fine controls too.

http://cgi.ebay.com/Mastech-Variable-Li ... 3|294%3A50

Jeffrey Weil
NorthBeach Holography Inc.

koliaco · Post by **koliaco** » Tue Jan 27, 2009 8:29 am

it might just be better to get a simple bench power supply

Thanks Jeffrey for advice. It would really handy to be able to control both VDC and A.
Unfortunately those items don't ship to New Zealand, and if they do probably another $100 for shipping

. I will try to source something like this locally, but here its much harder then in US.

walschuler · Post by **walschuler** » Mon Feb 02, 2009 7:41 am

I looked at the Slavich website for distributors for PFG-01 and they show Laser Reflections, but the address is out of date, and you know about Integraf, both west coast USA. I think the closest to you are in Taiwan and the PRC. You might contact Slavich directly as I suspect their website may be out of date....

koliaco · Post by **koliaco** » Tue Feb 03, 2009 7:34 am

walschuler wrote:I looked at the Slavich website for distributors for PFG-01

I think I will give a go with MBDCG first, as PFG-01 does not seem to be bright enough.

koliaco · Post by **koliaco** » Wed Feb 04, 2009 4:51 pm

Have anyone in here used the TEC controller MAX1978?

I have read the post "Wavelength stability requirements" about using the MAX1968, but since its accuracy can only be up to 0.01C compared to 0.001C of MAX1978 so I guess MAX1978 would be a better choice? I am thinking of building a circuit as in MAX1978PDF catalogue with a 30x30mm Peltier.

My another question is: should I connect the TEC controller to LD driver as the handrawn circuit in the above mentioned post or should they be separate? As I see that one end supplies +5V for MAX1968 and another end, which is close to the LD, supplies +8V and there is indication of separate grounds - so does that mean -5V and -8V ends are connected?

Any suggestion is highly appreciated!
Cheers

a_k · Post by **a_k** » Tue Feb 10, 2009 3:19 pm

MAX1978 is also a better choice because it needs fewer external parts. With MAX1968 you would need several additional precision opamps.

Unfortunately MAX1978 comes in a tiny QFN48 7x7mm package. MAX1968 is in a larger TSSOP package.