Multifunctional Environmental Digital Scanning Electron Microprobe (MEDSEM)

Chromologic (CL) and the California Institute of Technology (Caltech) propose to continue the Phase II STTR development and demonstration of a Multifunctional Environmental Digital Scanning Electron Microprobe (MEDSEM) instrument that transmits high energy beams of electrons sequentially using a two-dimensional array of multiple, miniaturized electron probes into a planetary atmosphere and strike solid or liquid planetary surfaces to simultaneously generate a wealth of spatially-mapped compositional information. MEDSEM will ultimately simultaneously measure X-ray Fluorescence (XRF), Backscattered Electron (BSE) Spectra, Optical Spectra (OS) and Mass Spectra (MS).

During the Phase II project Caltech will build on its transfer of electron-transmissive membrane technologies (Phase I) and further transfer to CL the technology for building an array of miniaturized, high-energy electron optic columns (EOCs) that are encapsulated by the microfabricated, electron-transmissive membranes for exciting XRF from samples in an atmospheric ambient. Electron field-emitter sources for these columns will be procured by Caltech from Stellarray Inc. and integrated with the high-energy electron columns. CL will manage the overall STTR Phase 2 project and assist Caltech in the fabrication and integration of EOCs, perform electron-optical and XRF-generation computer simulations to optimize the MEDSEM design, lead the testing and characterization of the Phase II MEDSEM prototype, and ultimately demonstrate the MEDSEM prototype performance.

The 24-month Phase II effort will be aimed at developing and demonstrating a prototype MEDSEM prototype instrument (TRL6). The MEDSEM prototype will be capable of generating high-energy electron beams (10-30 keV), transmitting them into the atmospheric ambient and generating characteristic XRF from suitable planetary mineral sample analogs.