Plane array

Kidder L H, Levin I W, Lewis E N, Kleiman V D and Heilweil E J 1997 Mercury cadmium telluride focal-plane array detection for mid-infrared Fourier-transform spectroscopic imaging Opt. Lett. 22 742-4... 

Ion detectors can be separated into two classes those that detect the arrival of all ions sequentially at one point (point ion collector) and those that detect the arrival of all ions simultaneously along a plane (array collector). This chapter discusses point collectors (detectors), while Chapter 29 focuses on array collectors (detectors). 

From the early 1980s to present, infrared sensitive two dimensional arrays were mated to integrated circuits for signal processing and sensitivity to better than 0.03 K (see Photodetectors). These focal plane arrays of some 500 by 500 elements eliminate the need for scanning and provide good spatial resolution. Some versions have no special cooling requirements. The development trend is to increase the number of pixels to improve resolution, increase the field of view and keep the size and cost of the optics within acceptable bounds. 

This chapter will concentrate on the very high quality detectors that are needed in scientific imagers and spectrographs, and other applications that require high sensitivity, such as acquisition and guiding, adaptive optics and interferometry. We limit our discussion to focal plane arrays - large two-dimensional arrays of pixels - as opposed to single pixel detectors (e.g., avalanche photodiodes). 

Limited temporal resolution - Focal plane arrays are aU inherently framing detectors and knowledge of the arrival time of photons is limited to the frame time of the detector. While the frame time can be quite short for adaptive optics detectors ( 1 ms), in most astronomical instruments the frame time is on the order of seconds or minutes, adequate for most astronomical science, but not all. 

Colorblind - As stated above, the focal plane arrays in use today can only detect intensity - wavelength must be provided by the optics of the instrument. 

Figure 4. Simplified schematic of an optical/infrared focal plane array. The detector is a thin wafer of light sensitive material that is connected to a thin layer of solid state electronics - the connection is made either by direct deposition (CCD) or bump bonding (IR detector). The solid state electronics amplify and read out the charge produced by the incident light.

Figure 5. Simplified schematic of the 2-D array of pixels in a focal plane array. The thin wafer of light sensitive material is partitioned into a two-dimensional array of pixels that collect the electric charge produced by the light. Each pixel is a three-dimensional volume that is defined by electric fields within the light sensitive material.

Although astronomy is accustomed to the detection of a few photons per pixel, the electric charge of a few electrons is extremely small. A critical part of the design of a focal plane array is the amplifier which converts the small amount of charge in each pixel into a signal that can be transmitted off the detector. The amplifier in an optical or infrared detectors is typically a field effect transistor (FET), a solid state structure which allows a very small amount... 

All of the optical and infrared focal plane arrays are solid state electronic devices, and to fully understand their physics and operation, one should have a solid foundation in the solid state electronics. An excellent reference is ... 

Unlike mapping, the detector used for infrared chemical imaging is a two-dimensional detector array. The infrared focal-plane array (FPA) detector, the long-wavelength analog of a typical digital camera, was... 

RJ. Treado, I.W. Levin and E.N. Lewis, Indium antimonide (InSb) focal plane array (FRA) detection for near-infrared imaging microscopy, Appl Spectrosc., 48(5), 607-615, (1994). 

E.N. Lewis and I.W. Levin, I.W., Real-time, mid-infrared spectroscopic imaging microscopy using indium antimo-nide focal-plane array detection, Appl. Spectrosc., 49(5), 672-678 (1995). 

The infrared radiation caused by the heat of reaction of an enantioselective enzyme-catalyzed transformation can be detected by modern photovoltaic infrared (IT)-thermographic cameras equipped with focal-plane array detectors. Specifically, in the lipase-catalyzed enantioselective acylation of racemic 1-phenylethanol (20), the (K)- and (S)-substrates were allowed to react separately in the wells of microtiter plates, the (7 )-alcohol showing hot spots in the IR-thermographic images (113,114). Thus, enantioselective enzymes can be identified in kinetic resolution. However, quantification has not been achieved thus far by this method, which means that only those mutants can be identified which have E values larger than 100 (113-115). 

P. W. Kruse, Principles of Uncooled Infrared Focal Plane Arrays... 

D. L. Folia and J. R. Choi, Monolithic Pyroelectric Bolometer Arrays N. Teranishi, Thermoelectric Uncooled Infrared Focal Plane Arrays M. F. Tompsett, Pyroelectric Vidicon... 

Sivco, and Alfred Y. Cho, Quantum Interference Effects in Intersubband Transitions H. C. Liu, Quantum Well Infrared Photodetector Physics and Novel Devices S. D. Gunapala and S. V. Bandara, Quantum Well Infrared Photodetector (QWIP) Focal Plane Arrays... 

Kirkwood, J., Al-Khaldi, S. F., Mossoba, M. M., Sedman, J., and Ismail, A. A. (2004). Fourier transform infrared bacteria identification with the use of a focal-plane-array detector and microarray printing. Appl. Spectrosc. 58,1364-1368. 

Figure 3.6 Schematicofa double-focusing sector field mass spectrograph with Mattauch-Herzog geometry with a linear imaging curve (double focusing for ions of all masses simultaneously) modified field combination with 70°. In the mass spectrograph, photographic ion detection or focal plane array detectors are used for quasi-simultaneous detection of separated ion beams. (H. Kienitz (ed.), Massen-spektrometrie (1968), Verlag Chemie, Weinheim. Reproduced by permission of Wiley-VCH)...

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