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I have a galvomotor with a specified maximum rotation of $20^o$, say $\pm10$. It's specified to rotate 1 mechanical degree per $0.5$ V. I shoot a red laser at the scanner mirror, the laser is then reflected to a target located at distance of 175.064 mm (focal length) from the mirror. I'm able to determine that it will be a maximum of $~ 63.718$ mm coverage area, $\pm31.895$ mm $[\tan20 \times 175.064 mm]$.

The issue I'm having is doing the conversion from $0.5$ V per 1 Mech degree to $1$ mm/[x]Volts. I want to be able to have a formula were I input a voltage, say 100 mV to in effect cause a 1mm beam movement at the 175.064 mm target.

TheImperfectCrazy
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j.valerio
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1 Answers1

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$x$ mm per volt is from $x=175.064 \times \tan 2V ^\circ$

An approximation to this is 6.1mm per volt, but it's only accurate for small angles. That means 1mm corresponds to about 0.16V.

If you want it more accurate do $\frac{1}{2} tan^{-1}(\frac{1}{175.064})$, about 164mV for 1mm, although the relation won't be linear for large angles.

If you could set up a curved screen, you could have a linear scale with $\frac{90}{175.064\pi }$ V per mm.

John Hunter
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