Thermal Expansion Mapper

The proposed innovation is aimed at the Focus Area 10 - Advanced Telescope Technologies, subtopic S2.03 - Advanced Optical Systems and Fabrication/Testing/Control Technologies for Extended-Ultraviolet/Optical and Infrared Telescope (Scope Title: Fabrication, Test, and Control of Advanced Optical Systems). Specifically, NASA needs a reliable, easy-to-use metrology solution that allows highly precise characterization of thermal expansion of large-format glass substrates (e.g. 4-m class Zerodur or 2-m class ULE). To address the NASA need, Hedgefog Research Inc. (HFR) proposes to continue development of its unique Thermal Expansion Mapper (TEM), which provides ultra-precise, rapid, nondestructive characterization of the coefficient of thermal expansion (CTE) homogeneity. HFRs TEM offers a highly sensitive, stable, and scalable sensor package with low system overhead that allows 1 ppb/K-level CTE characterization over a few days/weeks for large-format glass substrates. In TEM,HFR adopts multiple design features that eliminatevarious systematic/random error sources in displacement sensing, thereby providing high sensitivity and repeatability in the presence of environmental perturbations (e.g., temperature variation, vibration, presence of dust, etc.). This new characterization capability promises significant savings in time and cost by allowing the selection of mirror substrates before they undergo costly manufacturing process to turn into lightweight space mirrors for NASAs telescopes. NASA needs a reliable metrology solution that allows highly precise characterization of thermal expansion of large-format glass substrates. Hedgefog Research Inc. (HFR) proposes to continue development of its unique Thermal Expansion Mapper (TEM), which provides ultra-precise, rapid, nondestructive characterization of the coefficient of thermal expansion (CTE) homogeneity. TEM offers a highly sensitive, stable, and scalable sensor package with low system overhead that allows 1 ppb/K-level CTE characterization over a few days/weeks for large-format glass substrates. In TEM, HFR adopts multiple design features that eliminate various systematic/random error sources in displacement sensing, thereby providing high sensitivity and repeatability in the presence of environmental perturbations (e.g., temperature variation, vibration, dust, etc.). This new characterization capability promises significant savings in time and cost by allowing the selection of mirror substrates before they undergo costly manufacturing process to turn into lightweight space mirrors for telescopes. The overall goal of this project is to address the NASA’s need by demonstrating the benefits of TEM – new technology for mapping the inhomogeneity of CTE for telescope mirror substrates. We have established the following specific objectives to reach this goal: Objective 1. Develop a fully integrated TEM sensor module. Objective 2. Demonstrate the TEM capability to characterize CTE over a large area. Objective 3. Analyze the TEM system cost and define commercial markets. Deliverables: HFR will prepare and submit a new technology summary report, a new technology report if technology is developed, and reports in accordance with contract requirements.
Benefits: NASA applications are mainly focused on fundamental physics research, characterization of large and small optics and, possibly, aerospace components. In essence, TEM provides a simple and ultra-sensitive approach to mapping the CTE of various components, by employing a novel sensing scheme while leveraging mature commercial technologies. As the result, it promises a low-cost, versatile metrology solution that can be used in large-format mirror/lens production not just for NASA but many other branches of the Government and military contractors. Commercial applications of the technology include optics characterization, materials for aerospace, automotive, semiconductor industry (EUV lithography) and, possibly, medical instrumentation industry. All these applications require mapping of the inhomogeneity of CTE. Additionally, TEM technology may find uses in micro-optics.