Liquid light modulator not a jeffree

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Liquid light modulator not a jeffree

Postby Harry Dalek » Thu Jan 06, 2022 3:20 pm

Bit of a change today to try something i have been thinking about for a while a NBTV light modulator via liquid .
Here i am just getting teh idea together to work out a working experiment...what go's where and how to wire it .
Now i know from my last experiments with NBTV video transmitting in Liquids this works very well in Water using a tiny speaker transducer and Mic then using big picture to reproduce the video
viewtopic.php?f=1&t=2709&hilit=water
What i never tried and what has been in my head for a while to try is a similar experiment but this time seeing if the liquid with the video compression waves would effect light bit like a jeffree cell with out the ultra sonic side to it .
Hardly needed for NBTV only reason the jeffree cell had to use a 10MHz crystal was it was the only transducer with the bandwidth for 405 line television here i am working on audio frequencies
The laser light level will be adjustable passing though the liquid ,the speaker will transmit the video in the liquid hopefully changing the light levels enough so i can reproduce the video via the light that hits the solar cell pick up to reproduce the video on the pc as again as in the sound transmitting experiment in Liquids .
Might have to add a mask slit or tiny light hole to the experiment but see how it go's.
Reading the page below on minimum and maximum light passing though a Jeffree cell i think its the other way around no compression waves should give maximum light and minimum on compression ..or the liquid would be darker to start where as its a clear liquid ...it also seemed to be the effect when i used the idea on a working crystal /
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Liquid light modulator not a jeffree

Postby Harry Dalek » Fri Jan 07, 2022 8:02 pm

I pretty much got just built by this afternoon lots of factors that might effect things might not work at all ; 0 ) but hell its always fun trying .
Started off here using the UV laser i have a red laser and 3 colour Led just to see if the light frequency works better on the solar cell or what ever liquid to try .
A big factor would be volume compressing the liquid and what is used here i started off with water .
I can see the sound does have an effect just ..i should when i have time do a frequency sweep see if it shows up on the scope .
I forgot to make the sound dampening cork tight enough and first try it floated to the top whoops :roll:
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Liquid light modulator not a jeffree

Postby Klaas Robers » Sat Jan 08, 2022 12:37 am

Harry, a solar cell is most sensitive for near infra red light, wave length about 1000 nm. But red light is close to that. Red light has another advantage: you can see it, so you can see the light path.
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Re: Liquid light modulator not a jeffree

Postby Steve Anderson » Sat Jan 08, 2022 2:58 pm

Klaas is correct, any Silicon-based photo detector is always more sensitive to longer-wavelength light, red or IR, Whereas a tube photomultiplier is the opposite, i.e. blue or UV. A cadmium sulfide device (a LDR) has a peak around green, but is way too slow for this application and not very sensitive.

A typical Silicon light-sensor response is below, a BPW34 photodiode. The peak at 100% is at 850nm (Red), but at Blue (around 470nm) the response is only 30-35% of Red. Also Red light generally is easier and more efficient to generate than Blue.

Note the BPW34 doesn't have the black plastic IR filter used with IR detectors for remote controls and the like.

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I built a laser-based NBTV optical link some years ago, it appeared in the newsletter, but don't ask me which one!

Below you can see the BPW34 to the right bathed in the reflected red laser-diode light on the left. The input and output NBTV waveforms are shown below also.

Steve A.

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Re: Liquid light modulator not a jeffree

Postby Harry Dalek » Sat Jan 08, 2022 4:46 pm

Klaas Robers wrote:Harry, a solar cell is most sensitive for near infra red light, wave length about 1000 nm. But red light is close to that. Red light has another advantage: you can see it, so you can see the light path.


I sort of expected the solar cell to be more sensitive to something but i didn't know more into the red spectrum but i did factor in this you having each colour or use a white light LED later on .
Yes UV is not really that viewable to our eyes which is not a good thing as far danger to our eye sight but it is very viewable via a digital camera ..i will swap to a red Laser.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Liquid light modulator not a jeffree

Postby Harry Dalek » Sun Jan 09, 2022 10:30 am

I have to admit i found i had noise in my system laser no laser so results are not what i expected or were seeing at first .
i cleared that up so can start again i think i was getting a bit of signal via the power rails or jumping the plastic coated wires like a capacitor giving false results.
I found funny enough the UV laser does work better than the red on this solar cell could be its intensity but it still did better than the red when i cranked it up so need to look into this more .
So back to stage one :roll:
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Liquid light modulator not a jeffree

Postby Harry Dalek » Mon Jan 10, 2022 3:33 pm

Having a little think about it the transducer still has to work at higher levels similar to a normal transducer crystal on a jeffree cell not the frequency but levels to move the liquid or the light will not be effected enough .
As i recall from the last go at a Jeffree cell heat of the crystal vibrating the liquid was a real problem ...friction of the crystal or transducer on the liquid ! so boiling the liquid .
When i can i will see what this transducer can handle
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Liquid light modulator not a jeffree

Postby Harry Dalek » Thu Jan 13, 2022 1:04 pm

Today i wanted to see if the heating problem is still there at these lower frequencies i hooked up up the little transducer to a 18 watt amplifier and it sure does to the point the glass beaker boils the glycerine or water ..
So to tell the compression waves are enough the transducer just heats its self up and the liquid forcing its way out of the beaker .
Once again it melted the glue after a little time dropping the transducer in the liquid here's where i took the video ,the beaker start's to get very hot


So pretty much the same problem as last time if using a crystal at Mhz frequencies on a normal jeffree cell or at these lower audio frequencies the transducer fiction vibrating with enough amplitude kills the idea very messy too!
I can only think as with the last time i tried this with a normal jeffree cell but built to the correct size it would have to be topped up regularly .
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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