Ultra-low Reflectivity Black Silicon Pupil Masks

The ALD-Enhanced Far-to-Mid IR Camera Coating is fabricated by first applying a conductively loaded epoxy binder ~500 microns thick onto a conductive metal substrate (e.g., Cu, Al). This serves to provide high absorptance and low reflectance at the longest wavelength of interest, as well as to provide a mechanical buffer layer to reduce coating stress. Borosilicate glass microspheres are coated with a thin film metal via ALD, essentially turning the microspheres into resonators. That film is optically thin in the far infrared and approximates a resistive (~200 ohms per square) coating. Light trapped in the borosilicate glass microspheres is reflected back and forth within the glass–at each contact point, the light is attenuated by 50%. A monolayer of thin metal film-coated borosilicate glass microspheres is applied to the epoxy binder and cured, forming a robust mechanical structure that can be grounded to prevent deep dielectric charging by ionizing radiation in space. Once cured, the far-to-mid IR absorber structure can be coated with a traditional ~20-to-50 microns “black” absorptive paint to enhance the absorption band at short wavelengths, or a “white” diffusive paint to reject optical radiation. At this thickness and broad tolerance, the longwave response of the coating is preserved. Tailoring the electromagnetic properties of the coating layers and geometry enables realization of a broad band absorption response where the mass required per unit area has been minimized. While NASA originally developed the ALD-Enhanced Far-to-Mid IR Camera Coating for the Stratospheric Observatory for Infrared Astronomy mission, its robustness, absorptive qualities, and optical performance make it a significant addition to IR and terahertz imaging systems. The IR camera coating is at Technology Readiness Level (TRL) 3 (experimental proof-of-concept) and is available for patent licensing.

This innovation represents an alternative method to skip several of the conventional fabrication steps, using a mask designed to allow molecules in a sputtering plume to pass through openings engineered in the mask. This causes material to go where desired, without photoresist, and without selective etching, thus simplifying the process, reducing cost, chemical waste; and increasing throughput. This method masks areas that do not need deposited material, causing local deposition instead. The shape and size are within tolerance. No etching steps, no photoresist patterning, and no metal removal is necessary. Other than planarization, selective deposition has replaced every step in the conventional process, accomplishing the same result in 8 steps instead of 19. The technology can be easily used to fabricate custom chips and specialized sensors and devices that use the group III-V and II - VI semiconductor materials.

This invention provides a method and system for fabricating a biomarker sensor array by dispensing one or more entities using a precisely positioned, electrically biased nanoprobe immersed in a buffered fluid over a transparent substrate. Fine patterning of the substrate can be achieved by positioning and selectively biasing the probe in a particular region, changing the pH in a sharp, localized volume of fluid less than 100 nm in diameter, resulting in a selective processing of that region. One example of the implementation of this technique is related to Dip-Pen Nanolithography (DPN), where an Atomic Force Microscope probe can be used as a pen to write protein and DNA Aptamer inks on a transparent substrate functionalized with silane-based self-assembled monolayers. But it would be recognized that the invention has a much broader range of applicability. For example, the invention can be applied to formation of patterns using biological materials, chemical materials, metals, polymers, semiconductors, small molecules, organic and inorganic thins films, or any combination of these.

NASA’s imaging system is comprised of a small CMOS camera fitted with a C-mount lens affixed to a 3D-printed mount. Light from the high-intensity LED is passed through a lens that both diffuses and collimates the LED output, and this light is coupled onto the cameras optical axis using a 50:50 beam-splitting prism. Use of the collimating/diffusing lens to condition the LED output provides for an illumination source that is of similar diameter to the camera’s imaging lens. This is the feature that reduces or eliminates shadows that would otherwise be projected onto the subject plane as a result of refractive index variations in the imaged volume. By coupling the light from the LED unit onto the camera’s optical axis, reflections from windows – which are often present in wind tunnel facilities to allow for direct views of a test section – can be minimized or eliminated when the camera is placed at a small angle of incidence relative to the window’s surface. This effect is demonstrated in the image on the bottom left of the page. Eight imaging systems were fabricated and used for capturing background oriented schlieren (BOS) measurements of flow from a heat gun in the 11-by-11-foot test section of the NASA Ames Unitary Plan Wind Tunnel (see test setup on right). Two additional camera systems (not pictured) captured photogrammetry measurements.

Precision, Non-Contact Metrology measure optical surfaces with unusual prescriptions, high departure, and/or high slope error. This method has the advantage of being faster and more robust to systematic errors than other, more traditional, optical test techniques. Furthermore, it facilitates the accurate placement of optical surfaces within a system. The software and algorithm part of this innovation enables this hardware accomplishment. Measurement of aspheric mirrors of moderate size yields differences with interferometry of about ~30 nm RMS in terms of figure error. This technique pushes the limits of state-of-the-art coordinate measuring techniques toward enabling larger, lower cost, and higher quality freeform and aspheric optics, and their assemblies, decreasing the gap between commercial coordinate measuring techniques and interferometry and, for some applications, replacing interferometry and other optical shop techniques as the primary means of feedback to optical fabrication and requirements verification. Current and near-future applications for freeform and large optics would benefit from these techniques by reducing their cost and schedule and improving their technical risk posture.