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1.
Performance of a long-wave infrared hyperspectral imager using a Sagnac interferometer and an uncooled microbolometer array 总被引:1,自引:0,他引:1
Field and laboratory measurements using an interferometer spectrometer based on the Sagnac interferometer using a microbolometer array detector are presented. Remotely obtained signatures collected with this instrument and with a cryogenic IR spectrometer are compared and shown to closely correspond. Ground-to-ground and air-to-ground image products are presented that demonstrate the image quality of the sensor. Signal-to-noise measurements are presented and compared with a simple parametric performance model that predicts the sensor performance. The performance model is used to predict the performance of this technology when equipped with cooled detectors. 相似文献
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The possibilities of running digital holography using commonly available digital zoom photo-cameras are studied. A new modified method of the holographic set-up exploiting the properties of a photo-camera is suggested. This method offers a straightforward and simple way of both digital hologram recording and reconstructing. In order to verify the feasibility of the method, the holograms acquired are digitally reconstructed using a computer code based on the fast Fourier transform algorithm. Experimental results obtained are presented and discussed. 相似文献
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Several prism-based spectrographs employing a mercury cadmium telluride (MCT) focal plane array detector have been interfaced to an infrared microscope. In the combined system, the area-defining aperture of the microscope also served as the entrance slit to the spectrograph. This investigation considered the fundamental limits of diffraction for both the spectrograph and microscope in order to determine both the spatial and spectral resolution of the system as a whole. Experimental results for spectral resolution, spectral range, and peak-to-peak noise have been presented. Finally, the dynamic capabilities of one spectrograph/microscope combination were investigated. 相似文献
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Previously, we established the ability to collect infrared microspectroscopic images of large areas using a large radius hemisphere internal reflection element (IRE) with both a single point and a linear array detector. In this paper, preliminary work in applying this same method to a focal plane array (FPA) infrared imaging system is demonstrated. Mosaic tile imaging using a large radius germanium hemispherical IRE on a FPA Fourier transform infrared microscope imaging system can be used to image samples nearly 1.5 mm x 2 mm in size. A polymer film with a metal mask is imaged using this method for comparison to previous work. Images of hair and skin samples are presented, highlighting the complexity of this method. Comparisons are made between the linear array and FPA methods. 相似文献
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Krishna K. Deb 《Materials Research Innovations》1999,3(1):66-68
The current infrared microbolometer technology using vanadium oxide material is not quite as sensitive as a cooled platinum
silicide or cooled mercury cadmium telluride or indium antimonide array. The performance factor of the present IR bolometer
needs to be improved by at least an order of magnitude to make a bolometric IR device comparable to the cooled detector arrays.
I recently reported [1] that thin films of globular proteins such as cytochrome c exhibit a high temperature coefficient of
resistance (TCR) value of about 10% as compared with a value of 2.0 to 2.5% normally observed in VOx films. The measurements
that were initially reported were taken two weeks after the thin films had been prepared. The measurement of the TCR values
presented in this report were taken within three days of the films being prepared. These TCR values are very high, approximately
35% for temperatures between 25 and 60°C, and they have a sheet resistance around 1 to 2 Ω/cm2 with a current of 1 mA. The values of TCR were very uniform over the wafer surface, but the values varied slightly from wafer
to wafer. It appears that a cytochrome c monolayer on metal oxide semiconductor (CMOS) electronics could generate miniaturized,
uncooled IR detector arrays that would be suitable for military and commercial applications that require very high performance
and low-power drain. With these high TCR values, biological uncooled devices will have the potential for long-range thermal
imaging applications comparable to cooled detectors.
I have also examined the sheet resistance of the protein layer with an increase in the bias current near ambient temperature.
I found that the sheet resistance of cytochrome c rapidly goes towards the negative values as the bias current is increased.
On the other hand, TCR characteristics remained unchanged with an increase in bias current. This is a very interesting phenomenon
that has never been reported in biomolecules. I am making further explorations into the electrical properties of many proteins
for possible device applications.
Received: 8 February 1999/Reviewed and accepted: 9 February 1999 相似文献
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基于矢量阵测量的局部近场全息技术研究 总被引:3,自引:3,他引:0
统计最优近场声全息技术是通过全息面上测量声压的线性叠加来反演重建面上的声学量,可以从理论上克服基于傅氏变换的近场声全息技术的局限性。针对水中圆柱体的噪声源识别问题,采用声压和质点振速测量来进行声全息计算,推导了基于振速测量的统计最优柱面近场声全息技术的重建公式。利用所编制的程序进行了仿真验证,最后设计矢量水听器进行水中全息实验,验证了该方法的可行性和准确性,实验结果表明,该技术在水中柱形声源辐射声场的噪声源识别和定位中有着明显的优势。 相似文献
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基于声强测量的宽带声全息技术(BAH IM)是由近场声全息(NAH)领域脱颖而出的一项技术,它由全息面上互相垂直的两个切向声强分量计算出全息面上的复声压相位,得到全息面上复声压,再进行NAH处理。针对水中圆柱体的噪声源识别问题,给出了该方法在柱体中运用的基本原理,利用所编制的程序进行了仿真验证,最后,采用矢量阵进行了水中近场声全息测量实验,验证了该方法的可行性和准确性,实验结果表明柱面内BAH IM技术在水中柱形声源内辐射声场的重建噪声源识别和定位中有着明显的优势。 相似文献
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Akira Tonomura 《Journal of Superconductivity》1994,7(2):265-267
Individual vortices in superconductors are directly observed with our holography electron microscope. Vortices cannot be viewed as an electron micrograph, but only as a holographic interference micrograph or a defocused micrograph (Lorentz micrograph), since vortices are phase objects to the illumination electron beam. Since the flux itself, and not its replica, is detected, even the dynamic behavior can be observed. The dynamics of vortices in a Nb thin film can be observed in real time when the sample conditions, such as the temperature or the applied magnetic field, change. 相似文献
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One can correct spherical aberration in a transmission electron microscope by using a newly developed aberration-correction method involving off-axis electron holography. In this method, a liquid-crystal spatial-light modulator (LC SLM) is employed during the holographic reconstruction step to compensate for spherical aberration. Application of this method to high-resolution off-axis electron holograms of fine gold particles is presented. The phase distribution of the corrected object wave is visualized by the Zernike phase-contrast method carried out with the same LC SLM. 相似文献
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Measurement of curvature and twist is an important aspect in the study of object deformation. In recent years, several methods have been proposed to determine curvature and twist of a deformed object using digital shearography. Here we propose a novel method to determine the curvature and twist of a deformed object using digital holography and a complex phasor. A sine/cosine transformation method and two-dimensional short time Fourier transform are proposed subsequently to process the wrapped phase maps. It is shown that high-quality phase maps corresponding to curvature and twist can be obtained. An experiment is conducted to demonstrate the validity of the proposed method. 相似文献
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We present detailed theoretical evaluation and thorough experimental investigation of quantitative phase imaging using our previously demonstrated dual-plane in-line digital holographic microscopy technique [Opt. Lett. 35, 3426 (2010)]. This evaluation is based on the recording of two interferograms at slightly different planes and numerically reconstructing the object information. The zero-order diffracted wave is eliminated by using the method of subtraction of average intensity of the entire hologram, and the twin-image diffracted wave is removed by Fourier domain processing of the two recorded holograms. Experiments are performed using controlled amplitude and phase objects and human muscle cells to demonstrate the potential of this technique. 相似文献
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Qin ZD Ylitalo J Oksman J 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1989,36(5):485-493
A circular-array, pulse-echo, ultrasound holography imaging method is presented. The configuration of the measurement system is much simpler than that of traditional computed-tomography (CT) and compound beta-scan imaging. Wide-beam insonification is used. The geometrical differences of the circular array compared with a linear array system are corrected in the frequency domain of the hologram. The computation time of the reconstruction process for a circular image is practically the same as that of a linear array imaging process using the backward propagation (BP) principle. A fast Fourier transform (FFT) algorithm is directly used in the reconstruction process. Computer simulation shows that the resolution of this imaging method can surpass that of a linear-array system. In the preliminary experiments, 2-mm resolution was achieved in both the lateral and radial directions with an ultrasound frequency of 2 MHz. 相似文献
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Combining TV holography recording with acoustic phase stepping and image processing, we measure the integrated density distribution in sound fields that propagate in air. We record a given number of two-dimensional cross sections that are tomographically backprojected to give the amplitude and phase distributions of the emitted sound field. The validity of the procedure is demonstrated. 相似文献
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Vaithilingam S. Ma T-J. Furukawa Y. Wygant I.O. Xuefeng Z. De La Zerda A. Oralkan Omer Kamaya Aya Gambhir Sanjiv s. Jeffrey R. Brooke Khuri-Yakub Butrus T. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2009,56(11):2411-2419
In this paper, we describe using a 2-D array of capacitive micromachined ultrasonic transducers (CMUTs) to perform 3-D photoacoustic and acoustic imaging. A tunable optical parametric oscillator laser system that generates nanosecond laser pulses was used to induce the photoacoustic signals. To demonstrate the feasibility of the system, 2 different phantoms were imaged. The first phantom consisted of alternating black and transparent fishing lines of 180 μm and 150 μm diameter, respectively. The second phantom comprised polyethylene tubes, embedded in chicken breast tissue, filled with liquids such as the dye indocyanine green, pig blood, and a mixture of the 2. The tubes were embedded at a depth of 0.8 cm inside the tissue and were at an overall distance of 1.8 cm from the CMUT array. Two-dimensional cross-sectional slices and 3-D volume rendered images of pulse-echo data as well as photoacoustic data are presented. The profile and beamwidths of the fishing line are analyzed and compared with a numerical simulation carried out using the Field II ultrasound simulation software. We investigated using a large aperture (64 x 64 element array) to perform photoacoustic and acoustic imaging by mechanically scanning a smaller CMUT array (16 x 16 elements). Two-dimensional transducer arrays overcome many of the limitations of a mechanically scanned system and enable volumetric imaging. Advantages of CMUT technology for photoacoustic imaging include the ease of integration with electronics, ability to fabricate large, fully populated 2-D arrays with arbitrary geometries, wide-bandwidth arrays and high-frequency arrays. A CMUT based photoacoustic system is proposed as a viable alternative to a piezoelectric transducer based photoacoustic systems. 相似文献