When Applied Holographics were in full swing with that holocopier I remember sitting in the office of the leading light behind that enterprise,Hamish Shearer. We were both eying his nice goldfish in their aquarium when I had an idea.
“Why don’t we make a pulsed portrait of them ?” I asked.
We duly got a large 5 litre glass beaker filled it with water and Hamish carefully caught 2 of the smaller fish and we took it over to a spare ruby pulsed laser unit in a room there.
There was no safelight in that room if I remember rightly but I think we got enough light in to set up the experiment with an AGFA 8E75 plate by leaving the door slightly open. I simply rested the plate ( I think it may have been a rather expensive 10 x 8” ) against the beaker to shoot a simple Denisyuk in a single spread beam pulse of Ruby 694nm.
However for obvious health and safety reasons before we donned our goggles ready to shoot we had to lock the door , and this meant shooting the fish in pitch black darkness. I then put the exposed plate in a box and took it over to the lab to process.
Then as we both eagerly watched the finished plate under a spot light as it dried under a hot hairdryer we saw……………..
NOTHING! or almost nothing except for a bit of the brand name PYREX. Not the slightest hint of a fish. We then repeated the operation with another ($50?) plate. The result was again no sign of a fish! I was utterly perplexed….and pretty embarrassed and annoyed, I was there as a supposed expert on making and processing Denisyuks , How could this be happening ? The fish couldn't possibly be moving too fast for a 20ns pulse and in any case they would have made a shadowgram on the piece of white card we put behind the beaker for the second shoot.
Then we did some testing by turning the room lights on and off. The truth then was revealed .. .........
The moment the room went black those clever little bastards dived down and laid flat down on the bottom of the beaker!!
obviously some sort of evolved survival mechanism to protect themselves from powerful alien laser beams presumably.
We did on the third go finally manage to get our pulsed portrait of the fish but unfortunately…. it HAD to include an unedifying view of a Hamish arm as his hand had to rest on the bottom continually tickling the fish to keep them up in the picture frame.