Hi From Mike in Warwick, How did they do that?
I attended my first LEM UK meet this last weekend and what a fantastic time I had there too. My sincere thanks to all who made me feel welcome and for all the advise that came my way after me asking what seemed to be loads of questions. It was nice to meet up with those who I had spoken to on the phone, such as Rob of Stanwax, who puts to bed the often heard female conception that men can't multi task. This guy had his fingers in so many pies (well lasers actually) and still maintained focus on whatever job he had in hand! Thanks as usual Rob for your help on my two greenies.
My own interest in things coherent started off when I frequented a wine bar in Birmingham UK call Hawkins (any one else out there remember it), where they struck up an argon laser in a back room and projected liquid sky effects over the heads or even onto the punters. I was amazed and spent what seemed like ages trying to work out, what and how this was done and what caused that bright green speckled pattern in the back room when what was obviously a shutter dropped down in front of the beam. Soon after that, I visited the laserium at the planetarium in London to whitness a pair of green legs walking over the surface of the moon to the Police track "Walking on the Moon"...fantastic but how did they do that? At that time it seemed a closely guarded secret as to how it was achieved and I remember seeing the projector covered up as we left the auditorium. Its amazing that when we want to find out how somethings done we go to the ends to find out and my answers soon came in. It was during my university days and whilst working for British telecom that I eventually got to play with a large green water fed power hungry Coherent Argon laser at Loughborough university, 4 watts of green light and that speckle pattern all over again at my fingertips. I was working on speckle pattern interferometry to observe circuit board deformation, as British telecom had experienced some strange warping on some of its PABX boards. To do this we used holography. The objective was to learn the craft at Loughborough and transfer it to the lab at base built into an underground room which was very stable. Without going into all the technicalities of making a hologram, the idea was to create an H1 then place it precisely back into its mount on the optical table (superimposing its developed image over the said cct board), powering up the board switching on the laser and observing the now fringe patterns forming across the surface. The closer the fringes, the greater the deformation on the circuit board. Quantifying these fringes was another matter and for those who loved the maths then they were in their element! Anyway, apart from the serious stuff there was also the fun bits like a group Hologram taken with a pulsed ruby and magnifying glasses of circuits in the hologram etc etc. We also had fun with a massive CO2 laser, seeing how far through a brick it could go...cant see fun like that anymore with H&S looking down on us!
1 x Maplin HeNe and a budgie mirror over a speaker cone later, I was soon sending beams of red light around my bedroom, an argon being well out of my reach. Now I have two 500mW Green projectors (soon to have 2 x 1W blues fitted) and a 2.5W nominal RGB (actually measured 1.5W at the LEM meet) but with my new AR glass window hope to bring it up to 2 Watts, the make of this later projector I dare not say but a few may be able to guess. I am now enjoying browsing through the PL forum and soaking up so much info an array of 635nm will no doubt soon be popping a few green balloons ready for installation into the two green projectors.
I hope I have not bored anyone too much. All the best. Mike
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2 x Stanwax Laser 3W RGB's
