new fringe locker

[Joe Farina]

A couple photos of my new fringe locker are attached. It was tested today and works.

The schematic is shown on the Holowiki in the equipment section in the fringe-locking category. I think that one was c.1999, and I've found a better op-amp since then (the LF 356 instead of the 741). Other than that, it's the same. Also, I've had better luck with an ordinary small-sized 8-ohm (paper cone) speaker as the transducer for the moving mirror. I removed the paper (carefully, with an x-acto knife, to avoid cutting connections) and glued the mirror to the central paper tube (which is wound with fine wire) in the center of the speaker, which is the thing which moves in and out. Also, I'm beginning to think that the potentiometer for the speaker is unnecessary. I think all that's really needed is the potentiometer to vary the gain of the amp.

These lockers are quite simple, the parts are inexpensive. It needs two photodiodes, an 8-ohm mini-speaker (with a mirror glued to it), the LF 356, a potentiometer to adjust the gain, three resistors, and two 9-volt batteries.

[Colin Kaminski]

Very Nice!

[HoloM]

Nice, Colin!
For which recordings do you use it?
White light reflection copies?
Can you recognize any measurable improvements?
How do you integrate it in your setup?

[Colin Kaminski]

That is Joe's fringe locker. He has tons of experience with them. I have none.

[HoloM]

Ah sorry, my fault.
Same question to joe!