Re: CCD

You use two identical "gratings" or encoder strips. If you have a long linear strip with lines of equal width and spaces at for example 10 mil lines with 10 mil spacing as long as your table. Instead of trying to build a narrow enough light & sensor system, use a relatively large lamp and sensor but put a stationary encoder strip in between the moving one and the detector. If they line up perfectly, then 50% light will pass. If the long strip moves 10 mils, the lines will block all light and the output will be "0".

If you disassemble some encoders, you often will fine a small piece of stationary gating. That is its function.

Re: Floyd. It worked! I put up all the hurricane shutters and Floyd went away.
Bertho
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> From: David Howland <dhowland@...> wrote:
>
> Where does one obtain these devices? Who makes them? Any wind damage your area?
>
> -----Original Message-----
> From: Bertho Boman [SMTP:boman@...]
> Sent: Monday, September 20, 1999 8:22 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] CCD
>
> From: Bertho Boman <boman@...>
>
> David,
> The dual gratings side by sides avoids the problem that you are discussing with less and less signals. You have a "big" light source and a "big" photocell and the signal to noise is independent of grating size. The light goes from 0 to 50 % if you have 100 mil spacing, 10, 1 or what ever. That is how it is done on many commercial products.
> Bertho
> =============================
> ------------- >snip