Raymond W. Simpson

Self-scanned photodiode array: a multichannel spectrometric detector.

The performance characteristics of a 1024-element self-scanned photodiode array, related to its use as a multichannel spectrometric detector are described. The parameters discussed include, spectral and temporal response, blooming, geometric accuracy, noise sources, dynamic range, signal integration and spectral as well as spatial resolution.

Nonlinear AC and DC Polarization of Platinum Electrodes

The ac and dc induced nonlinearities of platinum electrodes in KCI solution were investigated and the effects of the rectification were significant only in the presence of externally applied dc. The experimental dependence of the overpotential as a function of applied ac and dc is presented and in qualitative agreement with the Tafel law.

Noise in large‐aperture self‐scanned diode arrays

An equation for the random noise of self-scanned silicon photodiode arrays is developed which includes significant terms not previously considered. It is shown that, including these terms, the new 2.5-mm-high self-scanned arrays are only slightly noisier than older arrays; but because of their much greater aperture, they can detect much smaller light fluxes than the older arrays even when used with simple, inexpensive amplifiers.

Medium speed gating of ISIT tubes

Image intensified silicon vidicon tubes (SITs) and doubly intensified vidicon tubes (ISITs) are useful in time‐resolved spectroscopy studies, when gated by a kilovolt pulse applied to the tube gate or photocathode electrode. An ISIT detector, used in conjunction with the Princeton Applied Research Corporation (PARC) optical multichannel analyzer (OMA), has been gated by HV pulses as short as 30–50 ns. A simple modification of that ISIT reduced the minimum gate pulse width of the ISIT to 5 ns. The time and spatial resolution are primarily limited by the pulse distortion introduced by the various stray reactances in the gate coupling circuitry, regardless of the conductivity of the photocathode.

Construction of an inexpensive platinum electrode

A method for fabrication of an inexpensive platinum electrode is presented. The process is based on the thermal deposition of a Pt film upon a glass substrate yielding a chemically inert electrode; the electrode is amenable to Pt blacking. The measured polarization capacitance for this electrode as a function of frequency is presented for both the bare and Pt blacked states.

CCDs for spectroscopy

CCDs have been used in spectroscopy for a number of years and for all the obvious reasons. Unfortunately most scientific CCDs are square arrays and are not ideally formatted for spectroscopic applications. This paper discuses the design and fabrication of two CCD arrays specifically intended for use in spectroscopic applications. The devices have 1100 X 330 and 1752 X 532 pixel formats, and are fabricated using the three phase, overlapping polysilicon gate technology and they are available in both front-illuminated as well as back- illuminated versions. In addition, devices with enhanced UV sensitivity are being fabricated. Characterization data are presented. The architecture of these devices leads to some interesting applications which we discuss briefly.

New camera for high-speed, high-dynamic-range digital imaging at 4,000 frames/second (burst rate) and 14-16 bits/pixel

A novel combination of techniques with a proprietary masked CCD allows economical commercial realization of a fast framing camera which can acquire images at 4,000 frames per second while maintaining the low readout noise of a slow scan scientific grade CCD system. A 16 bit gray scale dynamic range has been achieved in production with this system and even higher dynamic ranges appear possible in the near future with this technique. This imaging system can also be combined with a gated image intensifier to provide shutter times in the nanosecond domain.