25 May
2010
25 May
'10
3:48 p.m.
On 25 May 2010 at 19:33, Tony Duell wrote:
By using the in-focus signal (suitably derrived from
the
photodetectors) and seeing how much current you have to pass through
the focus coil to have the target object in focus?
I wonder if that would have the freqeucny response to read a wax
cylinderr? I think it should do...
Here's the design note:
http://tinyurl.com/2wzeyod
I wonder if, other than for establishing a baseline, it's necessary
to perform any focusing during the reading process itself. It seems
to me that the error output from the quadrant photodiode should
provide enough of a signal. I wonder if a wax cylinder would be
uniform enough in profile to use the technique, however.
--Chuck