Fall 2011


WiscSIMS is an instrument capable of analyzing chemical and isotopic makeup of samples on a submicron scale.  Exotic samples include comet dust.  PSL is helping improve WiscSIMS' capabilities.

PSL was originally contacted by Dr. Noriko Kita of the Geology & Geophysics Department regarding significantly improving the resolution of a visible light microscope (estimated at 3.7 microns) built into the WiscSIMS Secondary Ion Mass Spectrometer by converting the illumination to ultraviolet light (UV). PSL engineer Dan Wahl implemented an immediate economical improvement by replacing the halogen lamp with a blue LED, improving resolution by about 40% in linear dimension, to double in features per unit area. PSL engineer Ken Kriesel performed a follow-on project to evaluate what further resolution would be achievable versus expected costs, and found that significant further improvement was feasible with a near-UV LED at acceptable expense.  An interim upgrade was installed March 15, providing resolution of 2.1 microns or triple the original features per unit area.

An additional upgrade to 1.8 microns resolution or quadruple the original features per unit area is scheduled for late August.

While Geology is electing to terminate development at this level, significant further resolution improvement appears feasible.

Thanks go to the Ice Cube project for some use of their spectrophotometer, Jacob Zeuske in Mechanical Engineering for assistance with metrology of optics for QA, and to Rob McClain (Analytical Lab Director) at the UW-Madison Chemistry Department for offering the use of a spectrophotometer and UV-VIS monochromator and his invaluable assistance in their setup and use, aiding in the completion of this project.


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