Re: [CAD_CAM_EDM_DRO] Laser mouse based DRO

According to the documentation, deviation over the span of 4 inches is
about 5-10 "mouse counts" at 2000 dpi sensing. This means roughly
0.0035" error over a 4" span.

Peter Reilley wrote:

>I doubt that this would work very well in our applications.
>Laser mice operate by detecting the interference pattern
>produced by the laser light shining on an irregular surface.
>As the mouse moves the interference pattern moves.
>The amount of movement of the pattern relates to the
>amount of movement of the surface. The relationship is
>not necessarily linear. This is OK for a mouse but
>is useless for a CNC or DRO.
>
>For our applications it must be highly repeatable. The
>interference pattern is not repeatable in practical use.
>The interference pattern is sensitive to movement in
>all the X, Y and Y axes. Can you move in the X
>axis and have no movement in the Y or Z axis? Remember
>if you are off by a fraction of the wavelength of light
>in the Y or Z axis you have disturbed the X axis.
>
>There are laser interferometer DRO type devices but
>they operate completely differently. They also
>cost a lot more.
>
>Pete.
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