short range non contact distance sensor

Graham Stabler

I need to measure the vibrations of the upper surface of a honey bee's thorax in order to trigger a video camera shutter and a flash in a strobe system. The oscillations are of the order of 200hz and have very low amplitude (I'll have to look it up but lets say ~0.1mm). The thorax is small so the measurement system must be focussed or something.

I've been looking at these:

www.keyence.co.uk/products/sensors/laser/lvh37/lvh37.php

I've not checked the prices but I'm guessing it may be costly, any suggestions, it can be analogue or digital, the propeller is sorting out the timing of flash and camera.

Cheers,

Graham

Graham Stabler

Looks like my problem may be solved, I will instead mount the insect on the end of a record player stylus, the ceramic type once amplified will give me the required signal.

Graham

rjo_

hmmmm

or should I say "Bzzzzzzzzz"

Don't you need a 3D measurement?

So you would need to measure some angles... right?

You could try using a progressive scan video on the long axes... and use a flash/pop to synchronize the video data (you would have to inject something into your analog stream at the same time of course). You could then get angular data by doing image processing on both video streams. (ImageJ again[noparse]:)[/noparse] Assuming that you have a one inch bee...you should be able to get about .04 mm resolution.

Rich

Fred Hawkins

Graham, why not use a microphone? 200hz ought to be audible.

Lawson

How about a (small) capacitive sensor? Or mounting a tiny chunk of a rare earth magnet with a Hall sensor close by? (or a magneto resistive sensor for extra sensativity) I do like the record player stylus idea, cheap and high quality. Um... mount a tiny mirror and bounce a laser pointer off it? A carefully placed and amplified IR slot sensor might also be able to watch movements this small. (one of the wide slot ones, the bee would be the "blade" to partially block the slot) Similarly an IR proximity sensor with a suitable analog amplifier might also work. (zeroing and calibration would be hellish though)

Lots-o-ideas,
Marty

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Phil Pilgrim (PhiPi)

If the vibrations of the thorax are in phase with the wing beats, you could use sound to trigger your strobe.

-Phil

LoopyByteloose

Parallax has a piezo sensor that might do the job quite simple and cheap.

It may be physically easier to manage that the phono cartridge. It is flat.

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