InSb Focal Plane Array Detector Research Articles

Negative electrode structure design in InSb focal plane array detector for deformation reduction

When an indium antimonide (InSb) infrared focal plane array (IRFPA) is subjected to a thermal shock test, most of the cracks originate from the region over the negative electrode, which restricts its final yield. In light of the proposed equivalent modeling, three negative electrode structures are assessed to eliminate the accumulated deformation around the negative electrode. Simulation results show that when a thicker indium bump array is connected directly with negative InSb material, the accumulated thermal deformation is the minimum, the top surface of InSb chip is the smoothest, and the square checkerboard buckling pattern, present clearly in both gold buffer layer and sparse thicker indium bump array structure, seems to be unclear. All these mean that a thicker indium bump array structure is a good choice, which will benefit to reduce fracture probability of InSb IRFPAs under thermal shock.

Mid-infrared imaging with a solid immersion lens and broadband laser source

The application of hemispherical solid immersion lenses (SILs) is an approach to increasing the spatial resolution attainable with infrared (IR) microscopy. A hemispherical SIL forms an image for which the effective numerical aperture and magnification are increased by a factor of the SIL material index of refraction. A microscope designed for exploration of IR SIL imaging based on a hemispherical ZnSe SIL, an InSb focal plane array detector, and a broadband IR laser source is described. The imaging characteristics of this system are reported, including the spatial resolution improvement achieved in the imaging of organic test samples.

Investigation of Uncooled Microbolometer Focal Plane Array Infrared Camera for Quantitative Thermography

Thermal nondestructive evaluation has shown promise as a potential NDE technology for next generation US Army rotorcraft structures because it is rapid, noncontacting, and able to inspect complex geometries. To successfully apply thermal inspection systems for field use, the cost and size must be lowered. The infrared camera is a major factor contributing to the overall cost of commercially available thermal inspection systems. Recent advances in uncooled microbolometer focal plane array detectors have resulted in low cost, small size/weight, and low power consumption cameras. These attributes make this technology well suited for portable low cost thermal inspection systems. The purpose of this paper is to investigate the capabilities of the new microbolometer infrared cameras for quantitative thermal nondestructive evaluation. Quantitative thermal diffusivity and thickness images are obtained by minimizing the squared difference between the data and a thermal model on samples with fabricated defects. Critical infrared camera features such as spatial and temperature resolution, detector response time, and detector stability are studied by comparing results to a conventional thermal imaging camera using a cooled InSb focal plane array detector. Finally several techniques are presented to improve the camera’s performance. These techniques include temporal background subtraction, use of a synchronized electronic shutter system, and cyclic flash heating.

Multichannel and multicolour infrared thermography in Tore Supra

An imaging spectrometer using a sapphire prism as dispersing element has been conceived at Tore Supra for the spectral range of 1–4 μm. It measures simultaneously at various wavelengths the temperature on distributed high heat-flux elements under plasma impact with 36 optical fibers, four of which are ZrF4 fibers. It employs an InSb focal plane array detector (256*320 pixels) behind a silicon filter and a ZnS window yielding a dynamic range of 200–1500 °C with 20 ms temporal resolution. The fiber transmission and the spatial variation of gain and background of the camera are calibrated using a light source with integrating sphere. With a blackbody source one determines the nonlinearity of the average gain and controls its stability during operation. The spectral dispersion of about 24 nm/pixel is determined with interference filters and controlled with a spectral lamp. The measurements at various wavelengths allow to determine the temperature distribution in the field of view.

Design and Performance of a Planar Array Infrared Spectrograph That Operates in the 3400 to 2000 cm−1 Region

A prototype, no-moving-parts, plane array infrared spectrograph (PA-IR) capable of routine spectral acquisition in the 3400 to 2000 cm−1 region has been constructed. The instrument includes a continuous source, Czerney–Turner type monochromator system and an infrared camera that incorporates a 320 × 256 pixel InSb focal plane array detector cooled with liquid nitrogen. PA-IR spectra (∼3400 to 2550 cm−1) of polystyrene (PS) and poly(ethylene naphthalate) (PEN) films have been obtained at a resolution of ∼8 cm−1 with excellent signal-to-noise ratios (SNR). Peak-to-peak noise levels of ∼1 × 10−3 absorbance units are observed for single acquisition spectra with 1.5 ms integration times and 17 ms total acquisition times. Integration times as low as 10 μs are possible (with good SNR); however, data acquisition is limited by the frame rate (60 frames/s) of the software acquisition package currently used. In this work, an apertured image of the source is displayed over ∼20 rows of the array and the expected square root improvement in SNR is observed when multiple rows and/or frames are averaged. We have also shown that a square root improvement in SNR continues to occur with further signal averaging, providing noise levels as low as 1.5 × 10−5 absorbance units. Several additional advantages and options associated with the PA-IR method are discussed, including time-resolved spectroscopy, real-time monitoring, and spectroscopic mapping.

System for temperature and power flux measurements on the RFX first wall

A thermal imaging system has been installed on the RFX at Consorzio RFX to investigate the phenomenology of the plasma wall interactions. The infrared camera, model Amber AE4128, is based on a 128×128 InSb focal plane array detector and operates in the range of 4.5–5 μm with an acquisition rate of 217 Hz and 12 bit of dynamic range. The system, absolutely calibrated, is sensitive from room temperature up to 3000 °C, with different setups. The experimental data are compared with the numerical results obtained by means of transient thermal analyses carried out on analytical and finite element models of a graphite tile.

Controlling condensed-phase vibrational excitation with tailored infrared pulses

Vibrational population distributions within the CO-stretching T 1u manifold of W(CO) 6 in room-temperature n-hexane were created by using near-transform limited and linearly chirped picosecond infrared excitation pulses. These pulses were characterized using the second harmonic FROG (frequency-resolved optical gating) algorithm to determine the ∼8 cm −1/ps chirp for both positively- and negatively-chirped 2 ps pulses. FROG and time-resolved transient difference spectra were obtained with an InSb focal plane array detector. While unchirped and positively-chirped excitation leads predominantly to v=1 population, negatively-chirped pulses produce excess population in the v=2 level. These results are compared to predictions from density matrix calculations for a model potential.

Infrared spectroscopic chemical imaging

Infrared (IR) spectroscopy is a powerful, widely used technique for identifying materials or chemical compounds. An IR spectrum often provides a specific fingerprint for a given molecular component or species. IR frequencies, intensities, and line widths are also extremely sensitive to environmental perturbations and changes in molecular structure. Infrared spectroscopic images recorded through a Fourier transform infrared (FT-IR) microscope attachment have traditionally been constructed by translating a mapping stage a single pixel at a time through the sample area of interest; this is a very tedious and time-consuming procedure. Recently, a technique for rapidly performing high-fidelity FT-IR imaging spectroscopy using an indium antimonide (InSb) focal-plane array (FPA) detector coupled to an IR microscope and a step-scanning FT-IR spectrometer has been developed. These multichannel IR detectors were originally developed for thermal-imaging applications (mainly in the military), but they have tremendous potential as chemical imaging detectors when used as part of a spectrometer. The multiple detector elements enable images from all pixels to be collected simultaneously for each mirror retardation position of the interferometer. Use of an interferometer allows the entire IR spectrum over some wavelength range to be measured. The combination of a step-scanning FT-IR microscope and an InSb FPA detector provides unprecedented speed and image quality, limited only by the diffraction limit and/or the number of detector elements on the array.