Has anyone else tried making a pointer hologram without a shutter? I tried by turning it on with a switch for the same exposure time I had had good results with a shutter. These experiments made otherwise good holograms with limited depth. Thinking that the diode didn't have time to "warm up", I tried putting a resistance in series with the switch such that the diode barely glowed, thus being warmed up before throwing the switch for the exposure time. This also yielded a short coherence length. I did notice with a crude power meter (a CdS cell and an Ohm meter) that the output of my laser pointer takes about 2 hours to stabalize. Perhaps if I warmed the diode a bit it would be more coherent? Isn't heat the bane of laser diodes?
Paul Kline - Sun, Mar 07, 99 06:28:12 PM
I have not shot a hologram yet, but with a Michelson Interferometer setup I was able to determine that my pointer was not stable for a few seconds after switching on, maybe up to 10 seconds. And I have a beautifully simple circuit to drive it too - press the button, waits 10 seconds, turns on for set duration, turns off. One chip, a couple resistors and capacitors, and a transistor. Maybe it will power a shutter of some sort. 207.28.190.119
Steve Michael - Wed, Mar 10, 99 09:26:03 PM
I wouldn't even attempt this. All lasers need a certain time to stablize. I use a cardboard shutter and can make bright holograms after just 5 minutes of the laser pointer being on. I use the Infiniter 200 from Quarton (www.3dimagery.com/pointer4.html). If you want to place yourself further away from your table to decrease possible vibrations caused by air currents from you moving in the room, you can use a camera without the lens and a bulb-shutter release available a most photo stores. Hope this helps. 209.122.204.87
Frank - Thu, Mar 11, 99 11:52:15 PM
I read somewhere about someone once using a small transmissive LCD panel as a non-vibration method of shuttering. Can't recall for sure, but I believe that they pulled it from one of the hand-held kids video games like game boy or something like that. Sending a low voltage current to the panel turns it black and opaque, no current renders it clear. A hand-held thumb switch connected with a long wire was used for control away from the table. 207.16.159.220
Paul Kline - Fri, Mar 12, 99 04:34:33 PM
I want an electric shutter so the laser can be close to the object. I was able to remove the collimating lens from my pointer and the result is some of the most beautiful expanded coherent light. However it diverges very rapidly so needs to be close. Now if I can just find some time... 207.28.190.119
Chris Phoenix - Mon, Mar 15, 99 05:53:18 PM
An LCD panel polarizes the light that goes through it. If the panel looks clear but the laser doesn't go through, rotate the panel or laser until it does. I'm not sure, but I think if it's off a little bit you'll get partial transmission--this could steal brightness. (I haven't tried holography yet.) 205.149.174.105
John Klayer - Tue, Mar 16, 99 08:56:44 PM
I'd like to get back to my original posting: has anyone else tried making a pointer hologram without a shutter? As I said, I tried it with Agfa 8E75 and did get holograms with limited depth. As Steve Michael pointed out, all lasers need a certain time to stabalize. I understand this, that is why I wouldn't think of attempting this with a HeNe. But a diode is so small that the stabalizing time should be short. Paul Kline did a Michelson Interferometer test and found that the diode was not stable for up to 10 seconds after turn on. The Agfa no shutter tests I did had exposure times of about 10 seconds. So the exposure time was about the same as the stabalizing time. So, this isn't a good idea with Agfa film. But with the new slow Russian type films with their long exposure times this may work. I haven't bought any of the new films yet but will have to soon when my Agfa supply runs out. If I had some, I'd try it. Anyone else want to try it? There are some advantages if it works: one less component, ability to place the pointer closer to the spacial filter (before it spreads much). Also, I think I read somewhere a while back that one exposure technique for the new stuff involved a pre-exposure to white light for a second or two to get it over the "fat zero". Wouldn't the first light from the diode before stabalizing also accomplish that? 216.46.38.33
John Klayer - Sun, Mar 28, 99 03:19:08 AM
Have any of you with the new films and plates even thought of trying this? Come on now, somebody else must want to give it a try. I wasted a few Agfa plates and got limited depth. Are not any of you with the new stuff at least curious enough to give it a try? 216.46.38.33
Frank - Tue, Mar 30, 99 02:08:01 PM
We did a few multimeter tests on Sat. on the new 15mW diode, but before we put the 15mW on the meter we worked with the laser pointer running off batteries. For the first several seconds, the meter was very active measuring the mA the diode was pulling. It settled down somewhat after that, but for the time we had it on the meter (maybe around 10 minutes or so) it never really came to rest. It continued to vary from 49-50 or so mA (measuring in tenths) at 3v. Never left it on long enough to see it settle down entirely.
The 15mW was just as unstable for the first few seconds running off the PowerGeneral supply we were using, but it did lock in and held tight within the first 10 minutes.
The Slavich materials (03 in particular) recommend a latensification exposure as John noted above, but the literature calls for this as a POST exposure (after the main exposure with the laser is made). No idea whether pre- or post latensification makes a difference.
If it DOES makes a difference, then utilizing the diodes instability as a pre-latensification exposure would not work out.
It would be real nice to be able to control exposure with an on-off switch, but if this is not possible then we'll have to begin looking at a free-standing type of shutter system, similar to the traditional laser types. 207.16.159.181
John Myszkowski - Mon, Sep 27, 99 11:39:30 AM
I made electrically controlled shutters with DC motors and steppers. The simplest is with a small dc motor (like one from RadioShack) and a flag attached to the shaft. Flag has to have a good, positive attachment to the shaft, since it is stopped by two posts (on position and off position).
The best performance, and most quiet was the stepper motor, as it can be controlled to move only in small steps or combnination of small steps to make up larger steps.
the only critical aspect of this type of electro/mechanical shutter is possible vibrations. I suspended the shutter on soft springs to absorb vibrations, but even without the springs the shutter didn't seem to create significant vibrations.
Being experimentally minded, but extremely cautious I ended up using the shutter by having it sit on a small shelf totally removed from the table.
It can also be attached to the laser if it is off the table... probably (didn't try this yet). 24.141.84.254
Thomas Pietruszka - Thu, Nov 18, 99 01:59:40 PM
Thomas Pietruszka - Thu, Nov 18, 99 08:58:49 PM
Alan Edwards - Sun, Dec 12, 99 04:36:45 PM
Todd Johnson - Thu, Jan 13, 00 06:01:57 PM
blueeyedpop - Sat, Apr 07, 01 11:15:58 AM
Matthew - Fri, Apr 13, 01 11:24:21 AM
i recently noticed that The Electro-Optical Products Corporation @
For some reason or other, although i inserted the web address for Electo-Optical Products, the web adress did not get posted between the insertion key marks. Here is another try: (www.eopc.com). 208.12.123.73
Frank, How long does it take for your new 25mW setup
to stabilize with it's "fringe lock" circuit? 171.69.99.194
I made an electrically operated remote shutter about 14 years ago. It consists of an old milliampmeter with a little black painted foil flag glued to the needle. I drilled a 1/8" hole straight through the meter's face and out the back, about midpoint on the scale. The meter cover was removed and the inside was sprayed flat black and reassembled. It's mounted upside down in a small aluminum "Bud" box right in front of the laser so that gravity causes the flag-and-needle to hang down and cover the aperture. A cord connects to a box with a pushbutton, battery, and resistor (to limit the current to the meter so that it swings the flag out of the way without banging the stops.) This shutter activates slowly but smoothly in a perceptible fraction of a second and has been mounted right to my table with no vibration problems. I eventually built an electronic exposure timer which drives this shutter also. 131.225.122.15
I have just completed my shutter mechanism.
For the movement, I used the internal mechanism of a hard drive read head arm. I attached a flag to this. The hole where the spindle motor was makes a nice beam exit.
The circuit I used is a small microprocessor reading thumbwheel switches.
when you press a button, it waits a minute, then opens up and closes.
An npn transistor, with a potentiometer to limit the current helps to adjust the movement so that the flag hits no end-stops when it is actuated.
64.63.88.51
The simplest shutter design I've seen is in Iovine's book. He takes a Radio Shack analog voltmeter (you know, with the swinging arm) and takes off the clear pastic lens. He glues a small paper or cardboard "chad" (for lack of a better term) to the arm. He drills a hole through the voltmeter in a location that is covered by this chad when no current is going through the meter. Aim the laser through the hole. To open the shutter, apply a voltage through the meter. I haven't done this, but I image this would produce little to no vibration. 63.64.43.145