The pyradi toolkit is a Python toolkit to perform optical and infrared radiometry (flux flow) calculations.
The toolkit is available at http://code.google.com/p/pyradi
See docs at http://pyradi.googlecode.com/svn//trunk/doc/_build/html/index.html
Visit the google group at http://groups.google.com/group/pyradi-dev
The respective python files all have examples of use and simple test code at the end of each of the files. Execute these python files as scripts to execute the example code, and observe the results.