Publications

We demonstrate a 256 x 256 passive photon counting imager based on hybridization of back-illuminated silicon Geiger-mode avalanche photodiodes to an all-digital CMOS counting chip. Photon detection efficiencies in the 10%-20% are observed at visible wavelengths. The detection efficiency is currently limited by optical crosstalk that leads to elevation of...

The detection statistics of Geiger-mode photodetector subarrays with a combination of reset-time blocking loss and optical crosstalk are investigated. Closed-form expressions are obtained for the means and covariances of the numbers of counts in 2 x 2 subarrays (quad cells) used in Shack-Hartmann wavefront sensors. The predicted wavefront sensing precision...

Operation of a CCD imager on a curved focal surface offers advantages to flat focal planes, especially for lightweight, relatively simple optical systems. The first advantage is that the modulation transfer function can approach diffraction-limited performance for a spherical focal surface employed in large field-of-view or large-format imagers. The second...

Tungsten interconnects in silicon integrated circuits built at the 90 nm node with releasable configurations on silicon on insulator wafers serve as the basis for advanced forms of water-soluble electronics. These physically transient systems have potential uses in applications that range from temporary biomedical implants to zero-waste environmental sensors. Systemic...

An uncooled thermal imager is being developed based on a liquid crystal transducer. The liquid crystal transducer changes a long-wavelength infrared scene into a visible image as opposed to an electric signal in microbolometers. This approach has the potential for making a more flexible thermal sensor. One objective is to...

The TMT first light Adaptive Optics (AO) facility consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). NFIRAOS is a 60 x 60 laser guide star (LGS) multi-conjugate AO (MCAO) system, which provides uniform, diffraction-limited performance in the J, H, and K...

The Regolith x-ray Imaging Spectrometer (REXIS) is a coded-aperture soft x-ray imaging instrument on the OSIRIS-REx spacecraft to be launched in 2016. The spacecraft will fly to and orbit the near-Earth asteroid Bennu, while REXIS maps the elemental distribution on the asteroid using x-ray fluorescence. The detector consists of a...

Smart pixel imaging with computational-imaging arrays (SPICA) transfers image plane coding typically realized in the optical architecture to the digital domain of the focal plan array, thereby minimizing signal-to-noise losses associated with static filters or apertures and inherent diffraction concerns. MIT Lincoln Laboratory has been developing digital-pixel focal plane array...

We report on two recently developed charge-coupled devices (CCDs) for adaptive optics wavefront sensing, both designed to provide exceptional sensitivity (low noise and high quantum efficiency) in high-frame-rate low-latency readout applications. The first imager, the CCID75, is a back-illuminated 16-port 160x160 pixel CCD that has been demonstrated to operate at...

We demonstrate active hyperspectral imaging using a quantum-cascade laser (QCL) array as the illumination source and a digital-pixel focal-plane-array (DFPA) camera as the receiver. The multi-wavelength QCL array used in this work comprises 15 individually addressable QCLs in which the beams from all lasers are spatially overlapped using wavelength beam...