> I would like to build an angle sensor, and I thought the sensor in a
> mouse would do as well. Could anyone tell me the features of the mouse
> sensor? Sensitivity, ... ? I'd like to measure angles with a resolution
> of 0.57 degrees. What kind of output comes from a mouse? What signals are
> needed to be applied?

As other people have mentioned, a mouse's encoder
probably doesn't have sufficient resolution.

It might if you gear it up sufficiently using one or
more stages.  I'd use a cog belt to avoid slipage.
And sprockets plus cog belt is usually easier to make
in small quantities than gear trains.

If you're willing to buy an encoder, U.S. Digital makes
an extensive line.  They have shaft encoders with over
2000 counts per revolution.  Output signal is quadrature
encoded.  A friend of mine uses them for high resolution
telescope pointing (a commercial product).

They also have disk and linear patterns if you want
to "roll your own" encoder.  They have a web site at
http://www.usdigital.com.
                                                Lee Jones