Collimators are used in all X-ray and particle detectors as well as in multiple commercial applications that use X-ray imaging to maximize the sensitivity, resolution and contrast of images. State-of-the-art collimators can offer either high off-axis blocking or high on-axis transmission, and are heavy and bulky. MicroXact Inc.is proposing to continue the development of a particle collimator for NASA and commercial applications that will combine superior mechanical stability, light weight, improved Ly-a line suppression, with efficient off-axis blocking and high on-axis transmission efficiency. The proposed collimator is based on macroporous silicon with proprietary conformal pore wall coating. In Phase I of the project the MicroXact finalized the performance specifications, modeled and designed the collimator structure, demonstrated and optimized most critical fabricated steps, and demonstrated a-particle on-axis transmission meeting specifications to fully validate the proposed approach. In Phase II MicroXact will optimize the material fabrication, and design and fabricate a packaged particle collimator that will fully comply to NASA specifications and will perform testing in relevant environment. The collimators and antiscatter grids developed on this SBIR project will be commercialized in Phase III. Potential NASA Applications (Limit 1500 characters, approximately 150 words) Due to the unique advantages over competing technologies, the proposed MPSi particle collimators are expected to find a number of applications in NASA missions (, Explorer missions, Decadal survey missions IMAP, MEDICI, GDC, DYNAMICS, DRIVE Initiative, DISCOVERY, New Frontiers, and CubeSat, SmallSat missions, Sub-orbitals, and many more). Similar concept will work equally well with X-ray collimators for other NASA missions (such as ATHENA X-IFU and X-ray Surveyor, etc.). Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) Similar design of the particle and X-ray collimators is expected to find considerable DoE applications spanning from plasma parameter monitoring in tokamaks, X-ray and particle detection in accelerators, lightning and aurora studies, etc. The biggest market for the proposed component is X-ray antiscatter grid for medical X-ray imaging.