does anyone power thier diode with batteries only

Dave · Post by **Dave** » Sat May 01, 2004 7:25 am

after some trial and error i have had only dissapointment,after trying to use a DC power supply, the diode im using is a 35 mw @540 nm, i am ready to return
to my gas-fired he-ne !LOL

Michael Harrison · Post by **Michael Harrison** » Sat May 01, 2004 8:16 am

I know that JohnK does and Colin has done.

You either need to use batteries (apparently D-cells last a long time) or a well regulated supply.

When I was messing around with diodes I ended up using the latter. Not cheap, but I use the supply for other things in the lab so it all evens out (is it were).

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If someone says it can't be done but they haven't tried it, don't believe them.
http://www.dragonseye.com/Holography

Colin Kaminski · Post by **Colin Kaminski** » Sat May 01, 2004 11:06 am

Ah, the D&S circuit. Use 9V of batteries not 12! (You could even use 6V but that is a little light.) If you have a good ohm meter measure the resistance of the resistors R5 and R6 and make sure they are correct. I prefer 1% resistors for this. Measure the output power and make sure it is about 85 to 90% of the max power of your diode. If not you will need to adjust the valuse of R5+R6 until it is right. Putting a trim pot in series with R5 and R6 is a good idea if you have a power meter. Every diode has a different ratio of output power to light sensed by the photodiode. I think this is because it is hard to align the photodiode durring manufacture but that is only a guess. R5 and R6 set the ratio of input current to photodiode current. Really this is different for every individual diode.

You still may not be able to avoid the dreaded sliced bread holograms. However, the Mitsubishi diode has made some beautiful holograms with extremely long coherence length.