Laser Beam Profile Analysis in ImageJ

Posted by mleigh on Jan 29, 2009; 3:01pm
URL: http://imagej.273.s1.nabble.com/Laser-Beam-Profile-Analysis-in-ImageJ-tp3693862.html

We are trying to use ImageJ for laser beam profile analysis.  Thus, we want to accurately measure power in the beam, and use multiple methods to calculate beam diameter.  Also, we are analyzing field tests where the background changes from frame-to-frame due to clouds, sun movement, and other environmental effects.  

So far, I have not found any "laser beam profile" specific plug-ins.  Does anyone on the list know of any that have been written?  I have found the "Moment Calculator" which calculates the second moment, and thus can be turned into a "4 Sigma" beam width.  We are also looking to calculate the 1/e^2 width when the distribution is summed in the x and y directions, as well as the "90/10" beam width.  

Background subtraction is also a problem for us as the built-in "Rolling ball" method does not work well for beam images.  Other background subtraction methods also do not work as well since we have a dynamic background, and we want to preserve the pixel counts in the beam area for accurate measurement, and not just make a pretty picture. Right now we are taking two regions of interest per frame, and approximating the background as constant over the frame.  However, we would like to fit a well-behaved function to the background, and subtract off the background on a frame-by-frame basis for an entire stack.  We would like to do it sort of like it's done in the "A_Posteriori" plug-in, but using a region of interest, doing it on an entire stack, and subtracting the background without renormalizing the output.

If anyone has any ideas of ImageJ plug-ins that might implement some of these measurements, we would really appreciate it.  ImageJ is so much better and faster than the Ophir/Spiricon BeamStar software we were using.  After fighting BeamStar, we are very happy with ImageJ.