TravisAllen747
Introduction
For my course project, I wanted to learn more about the Image Systems Evaluation Toolbox (ISET) while incorporating some of my experience with optics and an optical design program known as Zemax OpticStudio. Several years ago (potentially 10-12 years ago), others had developed a basic capability for bringing lens parameters, as defined in Zemax, into ISET for use as "raytrace optics". The current implementation is pretty straightforward, but it is a bit dated. When this method was originally implemented, there was no inherent interoperability between Opticstudio and Matlab (the programming software that runs ISET). Now, in 2017, OpticStudio has options for interfacing with several external programs, including Matlab.
Since I was working alone and fairly unfamiliar with both ISET and the current method for interfacing with Opticstudio, my project began with the primary goal of taking a lens system in Zemax Opticstudio and importing it into ISET using the old method. Since the scripts that did this had not been used by anyone in quite some time, my plan was to work through each part of the process and fix anything that didn't work and clean up code that was unnecessary. My hope was to learn more about both ISET and Zemax OpticStudio along the way.
The second (stretch) goal was to try and modify the way the PSF's are currently applied in the raytrace optics chain in ISET. Currently, the PSF values are interpolated between field heights and wavelengths. A potentially better method, as described by Professor Wandell, would be to parameterize the PSF's as Gaussians and interpolate between those defining parameters (like variance). Unfortunately, I spent quite a bit of time on the first goal and was unable to make any meaningful progress on this second goal.
Background
In the Image Systems Evaluation Toolbox (ISET) in Matlab, one can simulate each part of an image capture chain: from the scene, to the optics, to the sensor, to the processor, and, finally, to the display. This project focused on the "optics" portion of that chain, which essentially transforms the scene radiance to the optical irradiance, which can then be captured by the simulated sensor. One lesser used method in ISET for describing and implementing this optics transformation system is called the "raytrace" method. The raytrace optics scripts and methods in ISET tend to revolve around output from Zemax Opticstudio, an optical systems modeling software that is widely used in the industry. Since these scripts are rarely used, some of the code has become outdated and needed to be cleaned up.
The main file that needed to be updated was the Zemax Opticstudio export macro. When the capability to import raytrace lens parameters from a program like OpticStudio was originally conceived, there was no straightforward method for exporting parameters into external programs (like Matlab) for manipulation. However, Zemax did allow for macro programming in order to rapidly execute tasks. So, about 10 years ago, the ISET team wrote a macro that went in, executed several commands, and exported data in a well-defined format. This macro is written in the .ZPL format which, when run, will output wavelength and field height-dependent Point Spread Functions (PSF's), relative illumination, and distortion parameters for the optics system currently loaded in OpticStudio. This macro had a lot of obsolete keywords that needed to be updated and a few parts that needed to be modified to work with more general lens files.
On the ISET side, there were some issues importing the files created by the macro and there was a logic error where wavelength and field height had been swapped in the import and interpolation scripts for both the distortion and relative illumination parameters. I fixed and cleaned up these issues in the scripts and created a basic tutorial script so that new people could go in and easily understand how to import raytrace optics files.
Methods
Results
Conclusions
Appendix
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