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Dear all,

We have a home-built two photon laser scanning microscopy. For that, we 
wrote our own software in Labwindows/CVI. Bascially it controlls the DAQ 
card's two output channels (for controlling the scan mirrors from 
Cambridge Technology), two input channels (for collecting data) and the 
motion controller (NEWPORT ESP7000, for moving the sample). The way we 
did it is like this:
1. Make sawtooth waveform for a single frame and send that to the two 
output channels.
2. Start output task and input task with a trigger.
3. Acquire data for that frame.
4. Stop output task and input task
5. Move to another position and repeat 1-4.
However, problem arises when we compare images at slightly different z 
positions or want to average a few frames. They don't match up quite 
well. There is a shift in the lateral or vertical position of about 
5-10pixels. I was wondering if anybody had any experience with this. If 
yes, is this an inherent problem with the scan mirror? Are there ways to 
improve it?
Thank you for your time.

Best Regards,
Dan

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Dan Fu
Dept. of Chemistry, Duke University
FFSC Room 2305, Box 90346 
124 Science Drive
Durham, NC 27708
Tel: (919) 660-1585; Fax: (919) 660-1605