Baffles just got me thinking of parallel restrictions . . .

How about a window low in one side of the tank with a UV LED shining in at a
small forward angle so that it doesn't shine across the tank to a detector;
*UNLESS* there is higher refractive index water in the way which bends the
light beam more than the low refractive index air does (higher bends towards
the normal).  With the right filters over the window no visible light will
get in to confuse your detector.

You could use a small cluster of LEDs at the light inlet port, or a special
lens to shape the beam from a single LED into a narrow, vertical column that
paints a series of detectors.  Only the detectors that are under water pick
up the refracted beam.

Bye.

> -----Original Message-----
> From: Andy Shaw [SMTP:andys@SCO.COM]
> Sent: Wednesday, 18 October 2000 15:55
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [EE]: Help water level
>
> Hi Again,
> Yep Been there got the baffles... !
>
> Andy
>
>

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