A5039857027- Adaptive optics and wavefront sensing
- CCD and CMOS Imaging Sensors
- Infrared Target Detection Methodologies
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Accounting Education and Careers
- Astronomy and Astrophysical Research
- Calibration and Measurement Techniques
- Corneal surgery and disorders
- Satellite Image Processing and Photogrammetry
- Ergonomics and Musculoskeletal Disorders
- Ocular Surface and Contact Lens
- Space exploration and regulation
- Optical Systems and Laser Technology
- Space Satellite Systems and Control
- Graphite, nuclear technology, radiation studies
- Auditing, Earnings Management, Governance
- AI in Service Interactions
- Real-Time Systems Scheduling
- Private Equity and Venture Capital
- Economic and Technological Innovation
- Antenna Design and Optimization
- Advanced Measurement and Metrology Techniques
- Securities Regulation and Market Practices
- Information Systems Theories and Implementation
University of California, Davis
2020-2024
SLAC National Accelerator Laboratory
2018-2024
Stanford Medicine
2020
Kavli Institute for Particle Astrophysics and Cosmology
2018-2019
Stanford University
2018-2019
Electronic Arts (United States)
2017-2019
United States Air Force Research Laboratory
2002
College of Optometrists
1987
Hanscom Air Force Base
1970
LSST Camera CCDs produced by the manufacturer e2v exhibit strong and novel residual charge images when exposed to bright sources. These manifest in following exposures both same pixel areas as source, pixels trailing between source serial register. Both of these pose systematic challenges Rubin Observatory Legacy Survey Space Time instrument signature removal. The latter trail region is especially impactful it affects a much larger area less well defined position. In our study this effect at...
In May 2019 SpaceX launched its first batch of 60 Starlink communication satellites, which surprised astronomers and laypeople with their appearance in the night sky. Astronomers have only now, a little over year later, accumulated enough observations constellation satellites like those being by OneWeb, run computer simulations likely impact when fully deployed, to thoroughly understand magnitude complexity problem. This research informed discussion at Satellite Constellations 1 (SATCON1)...
Abstract The Vera C. Rubin Observatory’s LSST Camera (LSSTCam) pixel response has been characterized using laboratory measurements with a grid of artificial stars. We quantify the contributions to photometry, centroid, point-spread function size, and shape measurement errors due small anomalies in LSSTCam CCDs. main sources those are quantum efficiency variations area induced by amplifier segmentation boundaries “tree-rings”—circular silicon doping concentration. This study stars projected...
The Bench for Optical Testing (BOT) is a test stand that will be used metrology and optical testing of the Large Synoptic Survey Telescope (LSST) Camera CCD sensors, immediately after integration step where sensors are installed into Cryostat to form LSST's 3.2 gigapixel, 640mm diameter focal plane. BOT uses existing methods economically verify sensor performance, including measurement plane flatness, spacing, gain stability, cross-talk, flat field images, response in each filter band, dark...
The Integration and Verification Testing of the Large Synoptic Survey Telescope (LSST) Camera is described. LSST will be largest astronomical camera ever constructed, featuring a 3.2 giga-pixel focal plane mosaic 189 CCDs with in-vacuum controllers readout, dedicated guider wavefront CCDs, three element corrector 1.6-meter diameter initial optic, six optical filters covering wavelengths from 320 to 1000 nm novel filter exchange mechanism, camera-control data acquisition capable digitizing...
Human corneal thickness was measured during daily wear of hydrogel contact lenses and then the initial 2 weeks extended hyper-thin (0.035 mm), low water content (38.6%), (polymacon). Results show that subjects wearing standard (0.12 mm) ultra-thin (0.07 for will exhibit a diurnal swelling cornea. Subjects minus power overnight (closed eye) cornea followed by deswelling throughout day (open eye). The degree can vary greatly among individual subjects.
The CCD sensors that will be used in the LSST Camera are controlled using a large number of bias and clock voltages. objective this project is to explore parameter space operating voltages optimize performance CCDs made by ITL, one two vendors manufacturing CCDs. were adjusted from their nominal values small increments electro-optical characteristics measured. These measurements performed first single ITL sensor later with 3 mosaic integrated controller electronics (Raft) engineering grade...
Thick, fully depleted charge-coupled devices (CCDs) are known to exhibit non-linear behavior at high signal levels due the dynamic of charges collecting in potential wells pixels, called brighter-fatter effect (BFE). This particularly impacts bright calibration stars, which appear larger than their intrinsic shape, creating a flux-dependent point-spread function (PSF) that if left unmitigated, could make up large fraction error budget Stage IV weak-lensing (WL) surveys such as Legacy Survey...
The Large Synoptic Survey Telescope, under construction in Chile, is an 8.4 m optical survey telescope with a dedicated 3.2 Giga-pixel camera. design and of the camera spearheaded at SLAC National Accelerator Laboratory here we present general overview integration test activities. An methodologies used for planning management this subsystem will be given, along high-level summary status major pieces I&T hardware. Finally brief update given on current state LSST Camera testing program.
The traditional characterization of charge transfer inefficiency (CTI) in charge-coupled devices (CCDs) can suffer from a number deficiencies: CTI is often only calculated for limited signal levels, pixels, and the sources are usually assumed to occur at every pixel-to-pixel transfer. A serial effects have been identified during preliminary testing CCDs developed by Imaging Technology Laboratory (ITL) use Large Synoptic Survey Telescope camera focal plane that motivated more comprehensive...
We examine the simple model put forth in a recent note by Loeb 2024 regarding brightness of space debris size range 1-10 cm and their impact on Rubin Observatory LSST transient object searches. Their main conclusion was that "image contamination untracked might pose bigger challenge [than large commercial satellite constellations LEO]". Following corrections improvements to this model, we calculate apparent tumbling Low Earth Orbit (LEO) various sizes, briefly discuss likely potential...
Abstract We examine the simple model put forth in a recent note by Loeb regarding brightness of space debris size range 1–10 cm and their impact on Rubin Observatory Legacy Survey Space Time (LSST) transient object searches. Their main conclusion was that “image contamination untracked might pose bigger challenge [than large commercial satellite constellations Low-Earth orbit].” Following corrections improvements to this model, we calculate apparent tumbling low-Earth orbit (LEO) various...
The LSST Camera for the Vera C. Rubin Observatory has been constructed at SLAC National Accelerator Laboratory. covers a 3.5-degree field of view with 3.2 gigapixels. goal survey is to provide well-understood astronomical source catalog community. Camera's focal plane populated by 189 sensors on science that are combination E2V CCD250 and ITL STA3800 deep-depletion, back-illuminated devices, accompanying eight guide sensors, four wavefront sensors. Nine grouped as "Raft" three identical...
Abstract Thick, fully depleted charge-coupled devices are known to exhibit nonlinear behavior at high signal levels due the dynamic of charges collecting in potential wells pixels, called brighter-fatter effect (BFE). The results distorted images bright calibration stars, creating a flux-dependent point-spread function that if left unmitigated, could make up large fraction error budget Stage IV weak-lensing (WL) surveys such as Legacy Survey Space and Time (LSST). In this paper, we analyze...
Polymethyl methacrylate (PMMA) lenses of known thickness were measured by one investigator with a pachometer. This experienced pachometrist held variation in measurements to within 1% over time. The repeatable SD less than 1%. data indicate that corneal changes should be greater 1 2% considered true thickness.
Electro-optical testing and characterization of the Vera C. Rubin Observatory Legacy Survey Space Time (LSST) Camera focal plane, consisting 205 charge-coupled devices (CCDs) arranged into 21 stand-alone Raft Tower Modules (RTMs) 4 Corner (CRTMs), is currently being performed at SLAC National Accelerator Laboratory. Testing camera sensors using a set custom-built optical projectors, designed to illuminate full plane or specific regions with series light illumination patterns: crosstalk...