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i have a 35 mw diode(650nm)im hoping will work for holography.i dont have a regulated power supply, so my question is ,can i use a stright battery supply with diode and circut? i understand the power loss over time ,if i ues fresh recharged batterys every time ,will this work (at least for testing)?

Batteries are VERY good for short-term stability, but as you say, the voltage drops slowly over time. The Sharp APC driver should more or less automatically compensate for this type of slow voltage change. I would recommend using 4 1.5 volt D cells or maybe a lantern battery to get 6 volts (more with fresh cells) and a silicon power diode in series (1N4001 or similar) to drop the voltage 0.7V to 5.3 V, which is closer to the specified 4.5-5.5V operating range of the Sharp chip. The chip will very likely work fine with 6+ volts (absolute max. is 10V), but it is only guaranteed to work as advertised from 4.5 to 5.5V. Or you could use a 3-terminal 5 volt voltage regulator - with newer "low dropout voltage" types, you could still run off 6V and would not require a heatsink for the regulator. An older 7805 type would work too, but would need a couple of additional volts to drive it, and would burn additional power - 7.5 volts is about the minimum you could use.

I would also recommend attaching the laser diode (or its heatsink) to a larger, heavier chunk of metal - not so much to remove heat, but to try to slow down the rate at which the diode temperature changes in response to stray air currents. Insulating the "heatsink" assembly would also be helpful. You could try the forum search feature for some combinations of the terms "laser diode mode hopping" to find past discussions of this topic.

I have found the 7805 does not like to have more that 13 volts put into it as well. I like to push it with 6 alkaline batteries. It seems to power the 35mw diode for a very long time. A 100 hours or so.

wow colin thats great, 100 hours! im running this laser with rechargable 4 AAs (i use for my digital camera). if all goes well i will invest in the "D" setup. Colin isnt 9 volts a little over the voltage top? at this point all i neeed is to produce one hologram ,and i will have some place to start.



we will see tonight!

As long as you have a 7805 in front 9V is not problem.