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ArcticMyst Security by Avery

DIY Holography Laser

Joined
Dec 11, 2011
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Hello everyone,

I want to share the work I just completed last night. I've built a DIY laser with a built in exposure timer to give accurate and consistent exposure times for hologram recording. The laser uses a basic LM317 constant current driver and a simple Monostable Multivibrator or "One Shot" based on the 555Timer IC. The laser runs off one 9V battery (3V Vf + 3V LM317 Dropout + 1.5V 2N4401 Dropout + another 2N4401 used to lop off the remaining 1.5V. 7.5V isn't the easiest to supply with 1.5V cells) and draws just 150mA from the battery.

This is a "50mW" chinese module which is basically just a 3.8mm diode in a 7mm housing and a 5mm diameter lens and spring. I think it cost me about $5. It is certainly far brighter than 50mW and did not lase at the current it was supposed to. It started lasing around 55mA and didn't really kick in until 80mA. I have it running around 120mA. The module (which is barely a heatsink at all) does not get warm to the touch with less than 60sec run times.


DIY Holography Laser - YouTube

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With these next two images you can see I had a hard time fitting it all in. Sometimes Ideas are Bigger than Boxes!
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Joined
Dec 29, 2011
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Very cool..

Thats what I was thinking about doing for a hologram laser (eventually)

I looked around, and realized I don't have any 555s at the moment!! Hehe.. Got all the resistors, and caps I'd need but no timers..

Oh well.. Need to remember to pick up a couple my next trip out to radio shack.

I was thinking about using some blown headphones for the nice flexible wire, and 1/8th plug, for a remote trigger button, as I don't know how you could hit the button on the box without moving the laser..

Put a 1/8th jack in the project box, plug in the remote trigger, and viola.. Vibration-free controlled exposure timing!

Looking good!
 
Joined
Dec 11, 2011
Messages
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Points
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Good point. I haven't had a problem with very sensitive momentary push buttons as long as you clamp or weight down the laser, but a remote trigger would be a nice addition!
 
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Where's the hologram?!

The regulator sounds good, however I don't think a 9 volt battery is what you want. 150mA is asking a lot from a 9V, and the runtime and stability will not be good. The exposure switch is a bad idea. You want the laser to be warmed up. Turning it on and off makes it less likely the laser will be stable during the exposure

When I purchased the holokit from integraf they recommended the laser be turned for at least 5-10 minutes before attempting to expose any film. The litiholo people also recommend this.
You've got to be able to leave the laser on, and use a piece of paper or your hand as a shutter.

Reflection (white light) holograms are very easy to create. You rest of the film next to or on top of whatever you want to hologram and expose to the 'raw' (no lens) laser diode's output.
 
Joined
Dec 11, 2011
Messages
4,364
Points
83
Where's the hologram?!

The regulator sounds good, however I don't think a 9 volt battery is what you want. 150mA is asking a lot from a 9V, and the runtime and stability will not be good. The exposure switch is a bad idea. You want the laser to be warmed up. Turning it on and off makes it less likely the laser will be stable during the exposure

When I purchased the holokit from integraf they recommended the laser be turned for at least 5-10 minutes before attempting to expose any film. The litiholo people also recommend this.
You've got to be able to leave the laser on, and use a piece of paper or your hand as a shutter.

Reflection (white light) holograms are very easy to create. You rest of the film next to or on top of whatever you want to hologram and expose to the 'raw' (no lens) laser diode's output.

While generally true I found the exact opposite to be the case here; The diode is powered up such a short time that it never changes temperature and thus isn't affected by instability issues. I've checked and the diode doesn't increase temperature 0.1degC during the 1sec on time. No temperature change = no wavelength change.

I tried two other diode lasers with the last batch of film, all warmed up for 15minutes, they were all rated for full 100% duty cycle, and I used the shutter method. Not a single plate out of five came out at all. No holograms.

I tried this laser without warming it up, with a ~4 second manual exposure on my last plate, and got my only successful hologram out of it.

The sole reason the holokit laser takes 15 minutes to stabilize is because they aren't using a constant current regulated driver or active cooling. According to them they use an adaptive driver which compensates for small temperature changes. It takes a while for the diode module to reach a thermal plateau, until that point the driver can't autocorrect for temperature.

I'd have some pictures of holograms for you but I haven't received my shipment of film plates yet, I expect them tuesday. I'll be mostly making reflection holograms, but I might try a transmission or two.


EDIT/UPDATE: I just noticed I never uploaded a video of a hologram. I made several reflection holos but it's very hard to get them to show up on camera. The next batch of plates will be transmission ones. The video is of a reflection holo, but I'm using a laser to show it off because otherwise my camera can't see it. Using the laser on a reflection holo makes it look pretty flat, but at least you can see the detail. This is proof the "need to warm up" is nonsense. If you diode is thermally stable it is thermally stable, it doesn't have to be warmed up to reach thermal stability if you do it right.

 
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