Thanks! For the one that partially worked I was using a 50-100mW 650nm (unLPM'd burner-equivalent diode like yours) also in a radioshack brick, haha. My diode is 3.8mm and has a massive divergence, so I have a very large even spread. I used this on two plates, but only one came out (reflection, 2ft distance, 4sec exposure, "straight on" alignment). The one that did not come out was transmission, also "straight on", 10sec exposure. I haven't tried the 45degree overhead alignment yet because I don't have anything to set the laser up on (like your flower pot) that is stable enough. I have a mic boom/stand with a clip on it that I can use but it isn't nearly as stable.
Aye, vibration is critical, unfortunately I live next to (300ft away from) a major trucking route and 50ton gravel and coal trucks go by randomly 24hrs a day. It is enough that every surface in the house vibrates a noticeable extent. I've been able to time things decently enough to miss any trucks, but the flooring also creaks and moves a lot so I have to be careful to not move at all while exposing the plates. So far I don't think vibration has been an issue. Someone walking a room or two over is enough to cause a 1mm shift in even the most stable surface I have.
I think the reason most lasers won't work is frequency (wavelength) shift. Truly stable lasers are expensive, and even though Integraf claims their 5mW diode is frequency locked, it really is not. It simply uses APC output regulation to keep the temperature of the diode as level as possible. This isn't really the same as single frequency emission. Only Gas or DPSS lasers are frequency locked without high end equipment design. Warming up the laser ahead of time just relies on the fact that any wavelength shift should have happened already. I did this with my 200mW handheld but it didn't seem to make a difference (again, I think exposure times were too long anyway).
I tried a 650nm 200mW unlimited duty cycle handheld focused for max divergence (can't remove the collimation lens) on four plates initially and not a single hologram came out. I didn't realise it but I was also exposing them too long (10sec) as well. With this one wavelength shift should not have been an issue, the laser runs cool continuously and was on for many minutes reaching equilibrium. This laser also has a massively long coherence length due to the collimated output, so I don't think lack of coherence is an issue either. Two plates were transmission, two were reflection. I set up the reflection ones exactly as their instructions showed and there was zero movement between the plates and subject. There might have been miniscule movement between the laser and plates but none that I could detect while exposing. The transmission ones I could not set up as overhead 45 degrees because I wasn't using flat/short objects, but rather objects larger than the plate, so I tried a "straight on" alignment as pictured where the laser hits both the target and the plate, with the target and plate 90 degrees off from each other and the laser 45 degrees off from either one (centered in the 90degree angle). Again, none came out at all. There is no red tint like there is in my partially functional one from the 4s exposure with the other laser and all plates have a very *light* yellow tint to them. The partially functional one has a much darker tint to it.
When I get my next batch of PFG-01 plates (12) I'll do two test plates trying out various exposure times to see what works best. I'll have a straight on reflection alignment and will be using the uncollimated brick laser. I'm planning on going with a one second exposure for one plate and the other I'll do a "classic test plate" with 500mS, 1S, 1500mS, and 2S exposures in vertical bands. I have a feeling the >1S ones will not come out the best though, haha.
The only other variable I can think of messing things up is my safelight. I've been using diffused monochromatic 473nm blue light as my safelight. I pulled up the sensitivity chart from Slavich who makes these plates after examining all other variables and discovered that these plates are indeed sensitive to blue light. There is a dip in, but not a total lack of, sensitivity in the green 540nm region and that is it. The dip in green is only a few units below the sensitivity to blue, which is only <2 units below the peak sensitivity to red. So, it is possible my safelight is not so safe. In the next round I will be using far less light than I was with my safelight to rule out this as a cause of error.
,,,,I was thinking a simple sandbox.
I don't use any sort of darkroom light. The film is developed in the darkest corner of the room, away from the laser. With dark adapted eyes there's just enough light in room (leaking though window blinds and from LEDs on appliances) to determine if the plate is dark or clear during development. When dropped into the 'A+B' catalysts the film plate will be rendered nearly opaque.. after bleaching it becomes clear again. See developer instructions.
