Recirculating Advanced Coupled-cavity Etalon Receiver (RACER)
Advanced Coupled-cavity Etalon (ACE) significantly improves both in-band transmission and out-of-band rejection. In some cases, 12% more light is transmitted inside the passband and >3x more light is rejected outside the passband. Incorporating ACE into the recirculating etalon receiver (RER) improves performance significantly. ACE increases the wavelength resolution and enables closer channel spacing resulting in a very efficient, high resolution spectrometer. RACER has both high resolution and a high photon efficiency which allows flexibility for trading different combinations of reduced cross-talk and closer channel spacing.
electrical and electronics
Microfabrication process for building x-ray absorbers
A thin (0.3 um) e-beam evaporated gold absorber is supported by small gold stems that are electroplated from the temperature sensor and substrate upward. The process is kept at temperatures less than 65C to prevent plastic deformation of the photoresist stem template. This is accomplished by using no reflow of the mold photoresist, curing the absorber-masking photoresist with UV exposure and a long, low temperature bake instead of a standard high temperature bake, and etching of the absorber using a wet chemistry at room temperature instead of the high temperature ion mill step. The completed absorber stops x-rays of energy less than 1 keV with high efficiency in the evaporated gold top layer, thermalizes the absorbed energy rapidly, and conducts heat to the temperature sensing part of a microcalorimeter via the electroplated support stems.
Method for Absolute Calibration and Tracking of Large Format Detectors Using Laser Radar
The purpose of this technology is to obtain charge coupled device (CCD) pixel location knowledge in 6 degrees of freedom with detector alignment precision of tens of microns of absolute uncertainty in a mechanical coordinate system. This non-contact approach involves the use of laser radar to obtain the orientation of the CCD pixels on a large format detector. This information can be used to align a detector in an optical system or interpolate image data from the CCD and correlate image features with physical locations in real space. The X, Y pixel value results for image analysis can be transformed into a three dimensional coordinate system. Using the laser radar, the CCD pixels are physically mapped and then related to external metrology targets on the detector housing. To accomplish this mapping, the laser radar is pointed at and focused on three or more locations on the detectors active area where a full frame readout of the detector is captured. This approach addresses a couple of technical challenges. The first challenge was to place a detector accurately and effectively as to have the OTE pupil image in plane with the detector pixels. Lastly, once the detector alignment is accomplished, how can the location of key features be established in the working coordinate system. This solution satisfies both of those challenges.
Automated Vision Test
The Wavefront Aberrations (WA) are a collection of different sorts of optical defects, including the familiar defocus and astigmatism that are corrected by eyeglasses, but also more complex higher order aberrations such as coma, spherical aberration, and others. The WA provide a comprehensive description of the optics of the eye, and thus determine the acuity. But until recently, a practical method of computing this relationship did not exist. Our solution to this problem is to simulate the observer performing the acuity task with an eye possessing a particular set of WA. When a letter is presented, we first distort a digital image of the letter by the specified WA, and add noise to mimic the noisiness of the visual system. From previous research, we have determined the appropriate noise level to match human performance. We then attempt to match the blurred noisy image to similarly blurred candidate letter images, and select the closest match. We repeat this for many trials at many letter sizes, and thereby determine the smallest letter than can be reliably identified: the visual acuity. We have streamlined and simplified the key steps for this simulation approach so that the entire process is robust, accurate, simple and fast. Results are typically obtained in a few seconds.
Hollow-Core Fiber Lamp
One end of JPL's HCPCF is fused with a piece of deep-UV fiber with a similar cladding diameter; both fiber types work at 194 nm. The other end of the HCPCF is attached to an ultrahigh vacuum system for lamp fabrication and mercury vapor is injected into the air core of the fiber with argon as a buffer gas. The HCPCF is heated near the vacuum side by a flame torch to seal the mercury and argon inside the fiber, and then the completed lamp is pinched off from the vacuum system. Light fulfilling the numerical aperture of the fiber can be collected along the fiber. The longer the fiber, the more light will be collected and output for use in mercury ion clocks and other applications. Since the HCPCF serves as both a plasma generator and a UV waveguide, the light output is orders of magnitude more intense than the light output of conventional mercury plasma discharge lamps. An HCPCF lamp has been demonstrated using a commercial HCPCF at a visible wavelength. HCPCFs at deep-UV wavelengths are not available commercially at this time.
Pressurized Oxygen via Solid Oxide Electrolysis
Originally conceived as a method to generate pressurized pure oxygen for extravehicular activity (EVA) suits worn on the International Space Station, Glenn's technology represents a significant breakthrough. The generator is an all-solid-state device that separates oxygen from air, water, or carbon dioxide and electrochemically pumps it to a high pressure in a multi-stage process. Glenn's design features a solid oxide electrolysis (SOE) stack, based on bi-supported cell design, that is structurally supported by two electrode layers. Sandwiched between the cathode and anode sides is an oxygen-ion conducting solid-state electrolyte membrane, made of yttria-stabilized zirconia (YSZ). These membranes form the individual SOE cells within the stack, and each cell carries out a single stage of the multi-stage process, with each stage incrementally pressurizing the oxygen. A voltage (1.5 to 2 volts) is applied across the cell, and the air or other input is supplied to the cathode side, where the oxygen dissociates into oxygen ions. The YSZ membrane will conduct only the oxygen ions, producing pure, dry oxygen. The entire stack is wrapped in a glass ceramic seal, providing a pressure vessel for the device. Glenn's novel stack design allows hermetic sealing and does not require a compression sealing mechanism or other spring-loaded hardware. Each cell is wired in parallel so the voltage can be controlled across each cell to avoid electrochemical reduction of the electrolyte. In addition, each cell is electrically insulated from other cells in the stack using a non-electronically conducting, ceramic-woven cloth YSZ layer. Because Glenn's process resists fouling from water containing impurities or other debris, it does not require a high-purity water source, as do other water electrolysis technologies. The oxygen product is also sterile for medical applications because of the high temperature (in excess of 600°C) at which the process operates.
information technology and software
Automatic Extraction of Planetary Image Features and Multi-Sensor Image Registration
NASAs Goddard Space Flight Centers method for the extraction of Lunar data and/or planetary features is a method developed to extract Lunar features based on the combination of several image processing techniques. The technology was developed to register images from multiple sensors and extract features from images in low-contrast and uneven illumination conditions. The image processing and registration techniques can include, but is not limited to, a watershed segmentation, marked point processes, graph cut algorithms, wavelet transforms, multiple birth and death algorithms and/or the generalized Hough Transform.
information technology and software
Hierarchical Image Segmentation (HSEG)
Currently, HSEG software is being used by Bartron Medical Imaging as a diagnostic tool to enhance medical imagery. Bartron Medical Imaging licensed the HSEG Technology from NASA Goddard adding color enhancement and developing MED-SEG, an FDA approved tool to help specialists interpret medical images. HSEG is available for licensing outside of the medical field (specifically for soft-tissue analysis).
Spatial Standard Observer (SSO)
The Spatial Standard Observer (SSO) provides a tool that allows measurement of the visibility of an element, or visual discriminability of two elements. The device may be used whenever it is necessary to measure or specify visibility or visual intensity. The SSO is based on a model of human vision, and has been calibrated by an extensive set of human test data. The SSO operates on a digital image or a pair of digital images. It computes a numerical measure of the perceptual strength of the single image, or of the visible difference between the two images. The visibility measurements are provided in units of Just Noticeable Differences (JND), a standard measure of perceptual intensity. A target that is just visible has a measure of 1 JND. The SSO will be useful in a wide variety of applications, most notably in the inspection of displays during the manufacturing process. It is also useful in for evaluating vision from unpiloted aerial vehicles (UAV) predicting visibility of UAVs from other aircraft, from the control tower of aircraft on runways, measuring visibility of damage to aircraft and to the shuttle orbiter, evaluation of legibility of text, icons or symbols in a graphical user interface, specification of camera and display resolution, inspection of displays during the manufacturing process, estimation of the quality of compressed digital video, and predicting outcomes of corrective laser eye surgery.
Interim, In Situ Additive Manufacturing Inspection
The in situ inspection technology for additive manufacturing combines different types of cameras strategically placed around the part to monitor its properties during construction. The IR cameras collect accurate temperature data to validate thermal math models, while the visual cameras obtain highly detailed data at the exact location of the laser to build accurate, as-built geometric models. Furthermore, certain adopted techniques (e.g., single to grouped pixels comparison to avoid bad/biased pixels) reduce false positive readings. NASA has developed and tested prototypes in both laser-sintered plastic and metal processes. The technology detected errors due to stray powder sparking and material layer lifts. Furthermore, the technology has the potential to detect anomalies in the property profile that are caused by errors due to stress, power density issues, incomplete melting, voids, incomplete fill, and layer lift-up. Three-dimensional models of the printed parts were reconstructed using only the collected data, which demonstrates the success and potential of the technology to provide a deeper understanding of the laser-metal interactions. By monitoring the print, layer by layer, in real-time, users can pause the process and make corrections to the build as needed, reducing material, energy, and time wasted in nonconforming parts.