Wanted: optics parts from video projector

[poormystic]

I need to make measurements of movements in the order of one micron, or a millionth of a meter.
In order to do that I need to get a beam of light to interfere with itself, using a modified Michelson Interferometer (see YouTube).
This means obtaining parts whose costs, as new devices, are mind-jamming, prohibitive.
There are actually some improvisations using quite cheap materials but building a quality instrument would be worth my while.
So!
I seek an irreparable, high quality video projector, from which I hope to scavenge optics parts. I can pay postage to Cairns.
Anybody?

 

[Delta Prime]

modified Michelson Interferometer (see YouTube

In order to grasp what peaked your interest please provide a link to what you have seen?

In order to do that I need to get a beam of light to interfere with itself,

You would like to culminate a particular color, wavelength, frequency of a coherent light source?

I seek an irreparable, high quality video projector, from which I hope to scavenge optics parts

Optics and slits share the same characteristics ; single optic defraction pattern and the double optic interference pattern. Single slit, double slit, also known as apertures must be identical along with the optics. Conducting experiments, is my kind of fun!
I gave an apprehensive quantum physicist a cat for Christmas. It's still in the box.

 

[poormystic]

I'm playing with ThorLabs' piezoelectric actuators, which can move quite heavy things very abruptly and often, but not very far... a maximum of a few micrometers full scale, in fact.
I have several dreams of what I might do with these fairly high power devices. (My original idea of making diffraction gratings, is no longer as interesting to me.)

Fun ideas are not cheap ideas - certainly not when ThorLabs are supplying the bits... However for a few (more) grand I could conceivably build a continuously adjustable visible light interference filter. This would be good fun if it worked! It'd be hard to keep cool, though. (I have a more likely idea I don't want to discuss openly yet, just in case it's saleable )
Anyway, a Michelson interferometer could enable me to measure movements of a micron - Iff! I can afford a laser with sufficient coherence length. By using several detectors it is possible to determine "sense" - whether the movement is positive or negative.

I suspect that the Michelson interferometer might be a much more challenging job than I would prefer.
However, I can get a beam splitter from an old video projector, and somewhere in the world is a 9th hand theodolite, so I'm assessing the job as though I might complete it.

 

[Delta Prime]

I suspect that the Michelson interferometer might be a much more challenging job than I would prefer.

How about an Michelson interferometer Kit

You have the right idea, and as you stated the components can be found for repurposing quite easily adjustable lens and mirror mounts, magnetic strips, beam splitter, small mirrors, short focal-length lens, laser pointer.
I’m quite partial to the Mach-Zehnder interferometers myself.

 

[poormystic]

Hi! to all readers.
I now have a 532nm semiconductor laser. With my laser, and parts from the video projector, and some kind of solid table, I can make a modified Mach Zehnder interferometer to measure my tiny displacements.
So... smiles - but I also have some misgivings about the thread, which has indeed strayed well beyond electronics.
I have PM'd Delta Prime and Davenn (whose daily work goes into this area) and hope to continue the discussion there. (Of course, if the moderators were to allow it, I'd happily discuss this further here.)
Plans:
I hope/expect that I can use 3 slits, with phototransistors, to detect the amount and sense of the movements of my PZT piezoelectric actuators.
I'll probably end up making several slits in a black screen (carbon black on glass, slitted with a razor blade) and experimenting to find the 3 particular slits I need.
Mm hmmm, it's good to make progress

Thanks!

 

[Delta Prime]

have PM'd Delta Prime and Davenn (whose daily work goes into this area) and hope to continue the discussion there.

I’m already on double secret probation thanks a bunch… how about you and me travel down to homework and give them all the answers

 

[poormystic]

Looks like Delta Prime is living a double life... but perhaps The Boss might have a window into his secrets.
I like the MZ interferometer better than the Michelson because there is no need for an ($) optical isolator.

 

[Delta Prime]

Looks like Delta Prime is living a double life

I have never seen an Impoverished
Mystic without a Cristal Ball…


Uncertainty Principle equation
Look closely into my crystal ball…


A Mach-Zehnder interferometer: In standard quantum mechanics, the probability wave divides at beam splitter BS1 and self interference occurs as the partial waves recombine at BS2.As now proposed by using your 532nm semiconductor laser,the scattering of a photon into one or other arm at BS1 induces by reaction a fluctuation in the re-radiation field,& it is this that interferes with the photon at BS2.This response will constitute a microscopic imbalance in the scattering medium of the apparatus.The tendency of the apparatus to resist the accumulation of imbalance will be the source of the Born probabilities. The evolution of the imbalance through the experiment will explain the seemingly probabilistic alternative states that have been discerned in quantum measurements.
When do you wanna get started??

 

[poormystic]

I have never seen an Impoverished
Mystic without a Cristal Ball…
View attachment 65916

Uncertainty Principle equation
Look closely into my crystal ball…

View attachment 65917
A Mach-Zehnder interferometer: In standard quantum mechanics, the probability wave divides at beam splitter BS1 and self interference occurs as the partial waves recombine at BS2.As now proposed by using your 532nm semiconductor laser,the scattering of a photon into one or other arm at BS1 induces by reaction a fluctuation in the re-radiation field,& it is this that interferes with the photon at BS2.This response will constitute a microscopic imbalance in the scattering medium of the apparatus.The tendency of the apparatus to resist the accumulation of imbalance will be the source of the Born probabilities. The evolution of the imbalance through the experiment will explain the seemingly probabilistic alternative states that have been discerned in quantum measurements.
When do you wanna get started??

Well, well.
Sounds simple as a limit theorem to me. So QED has become part of my life (surprise emoji). Long, slow stuff, QED, by all reports.

As for getting started, I found a cheap, dead handymans laser and it's on the bench now.
It's a TUF brand green laser with 2 output lenses arranged in a T configuration. I don't know how many lasers are fitted into the gimbaled casting - I suppose just one.

I opened the instrument up and found a broken wire, that seems to have been jammed into a corner during some previous reassembly. A bit of the pcb has been broken too, which looks like a "frustration injury". I'll get it going, hopefully, tomorrow.

One thing I don't want to forget is that Michelson, Morley, Mach and Zehnder had this in common ~ they lived before lasers became available. So things ought be much easier for me.

My 1980's video projector, with lots of wanted optics parts, might arrive in 10 days.

 

[Delta Prime]

One thing I don't want to forget is that Michelson, Morley, Mach and Zehnder had this in common ~ they lived before lasers became available. So things ought be much easier for me

Make no mistake we will be reproducing the successful experimentation as our forefathers…

I now have a 532nm semiconductor laser. With my laser,

For your safety please consider



532 nm neon green photons will not damage your vision while wearing the goggles of your choice; by the way, I wouldn’t pay-more than 100 bucks for a pair.

 

[poormystic]

.
Thank you very much, Delta Prime.
It's essential to wear such eye protection, even when working with very low power lasers, isn't it. Laser related eye damage is accumulative.

I admit it... I feel very reasonably afraid of lasers... not quite as afraid as in the case of self-surgery, but close. I must take very great care.
Apropos which: I'll cover the laser lenses with translucent tissue paper while it's under repair.

I was already thinking of getting ultra black paint for the enclosure around the optics bench, as well as nearly everything on the optics bench, to reduce unwanted reflections. Are there any further systemic precautions that anyone can think of?
With thanks for your thoughts...
Mark

 

[poormystic]

Thinky, thinky...
I'm thinking that BS2 in Delta Prime's drawing ought be a non-polarising beam splitting prism, so that I obtain a long, parallel interference path, or prism of light in free space, within which to place my detectors.

 

[Delta Prime]

I was already thinking of getting ultra black paint for the enclosure around the optics bench, as well as nearly everything on the optics bench, to reduce unwanted reflections

For your consideration: Vantablack has been developed by UK based Surrey Nanosystems. The substance is so black that it absorbs 99.96% of incident light falling on it and is nearly the perfect black body.

https://maker.pro/forums/threads/and-now-something-weird.293263/post-1855942