pgFocus is something I have been working on and off again at work and I would like to share it here.
It is better described at http://valelab.ucsf.edu/~MM/MMwiki/index.php/PgFocus (Documentation is still a work in progress)
In short, pgFocus is designed to stabilize focus on a microscope by using a reflected laser beam.
The inspiration for pgFocus first started when I ordered a Arduino for work because I wanted to monitor room temperature and I was curious about the Arduino. Later, I thought I could use an Arduino to solve a long standing problem with high performance TIRF imaging. The problem was focus drift over time. TIRF allows the imaging of a narrow 200nM space above the glass/water interface, so it doesn't take much drift to ruin TIRF imaging. Commercial focus correction devices don't integrate well with custom designed microscopes. Commercial versions are also very expensive and are called names like "Perfect Focus" and "Definite Focus". I decided to build my own and call it pgFocus. pg = "Pretty Good". It makes me laugh.
The concept for pgFocus came to me one Saturday night. I might have been watching "Ask an Engineer" at the time. I am a software guy, but I taught myself basic circuit design and I had my first pgFocus prototype working and integrated into our microscope within a few months.
I have just released the pgFocus design (see https://github.com/kbellve/pgFocus ) .
Please point out any mistakes I made or if there are possible areas for improvements before sending off a PCB order.