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Two packaged EMCCDs (e2v) that have been delta doped and AR coated for the FIREBall experiment. The different colors (dark purple and light blue) result from differences in the AR coating design.

MDL News & Trends

This Year Marked an Exciting Period for MDL in Advanced Detectors, Systems, and Nanosciences

The Keck Institute for Space Studies (KISS) funded a technology development program for next-generation ultraviolet instrument technologies. Under this program, MDL developed single- and multiple-layer antireflection (AR) coatings for integration with silicon-based detectors. Coatings are applied directly to the detector surface by Atomic Layer Deposition (ALD), which offers nanometer-scale control over film thickness and interface quality, allowing for precision growth of multilayer films. JPL will deliver 2-megapixel, delta-doped, AR-coated electron-multiplying CCDs (EMCCDs) for the FIREBall experiment designed to measure emission from HI, OVI, and CIV, all red-shifted to the stratospheric balloon window (195–215 nm). This combination results in a photon-counting detector with quantum efficiency (QE) > 70% at 205 nm, nearly an order of magnitude higher than the previously flown FIREBall-1 detector based on microchannel plate technology.

On-Sky Observation with Broadband Detectors

MDL recently developed and delivered broadband silicon CCD arrays for the Wafer Scale camera at Prime focus (WaSP) instrument, an upgrade to the current prime focus imager at Palomar Observatory’s 200-inch Hale telescope. These dedicated 4-megapixel guide and focus CCDs are required to maintain both telescope tracking (during long exposures) and focus (during a night’s observing). JPL’s superlattice-doping technology combined with multilayer AR coatings prepared by ALD delivers enhanced blue sensitivity with high quantum efficiency optimized over 320–1000 nm.

This is highly advantageous when observing through short wavelength filters where suitable guide stars (for tracking and guiding) become faint and CCD throughput typically drops. These 2kx2k, 15-µm pixel deep-depletion CCD arrays are designed by STA and fabricated at Teledyne DALSA. Custom packaging and wire-bonding techniques were designed at JPL to meet the special needs of the WaSP instrument for a closely packed camera.

Ultraviolet Spectrometer Based on JPL’s Ultraviolet Technologies

The Ultraviolet Spectrometer (UVS) project is part of the effort to create a compact, high-performance instrument utilizing several key technologies pioneered at MDL. The first technology is high performance ultraviolet detectors using delta doping and superlattice doping developed at JPL. The second technology is electron-beam fabricated gratings on curved substrate enabling compact and efficient optical designs such as a compact Offner imaging spectrometer. The third technology is in the development of tuned optical filters and coatings directly deposited on detectors as well as efficient, high-reflectivity coatings on optical surfaces such as spectrometer mirrors and gratings using ALD. This process enables finer control over spectral parameters and improved optical efficiency.