I don't have much experience yet with video capture used in optics
experiments. One issue is resolution. The 8 bits of grey scale intensity
can be problematic when there are wide intensity variations, such as in
single slit diffraction. But one can imagine workarounds. (I haven't
read the AJP article.) We did try imaging a double slit pattern one day.
As I recall, in the short time we messed around with it, we easily got
images from which one could extract fringe spacing data, but laser
speckle, cleanliness of the films containing the slits, and beam quality
of the laser, combined to make the amplitude variations look far from
the ideal in the text. With more work it could have been better looking
and some image processing would have helped a lot.
I presume a Snappy image can be saved as one of the standard file
formats such as JPG or GIF. If it were to be imported into PaintShop you
could certainly extract intensity information. If I recall correctly,
PaintShop might even have a function that plots a graph of the intensity
variations along a click-and-drag line. PaintShop has gone pretty high
end and has lots of image processing functions now, though of course
more oriented toward making pleasing images rather than quantitative
measurements.
Higher up on the price scale is IDL from Research Systems, Inc. A nice
tool that can be a complete data analysis/programming system, but which
started as an image processing system. So it has a wealth of image
routines.
Digital (motion) video capture boards like the Video Blaster come in two
flavors and I can't remember which kind the Video Blaster is. One flavor
involves a jumper cable from the computer video graphics adapter to the
capture card and then the monitor plugs into the capture card. This is
called overlay video where the capture card takes over the task of
displaying video on the monitor screen. If that is the case, then ignore
the rest. If the monitor stays plugged into the computer graphics card,
then it isn't overlay video, the video is displayed as part of the
computer graphics system. Generally this became possible with the advent
of the PCI video cards. If so, PhysVis, our digital video analysis
program, can be used to extract intensity information as a function of
time or position for out put to your favorite plotting software.
PhysVis is freeware and can be downloaded from
ftp.kenyon.edu/pub/physics/SOFTWARE/WINDOWS/PHYSVIS. Our AJP article
about PhysVis is online at
www.kenyon.edu/depts/physics/research/addeyes.htm.