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An uncooled VGA Infrared Focal Plane Array (IRFPA) based on microbolometers with a pixel pitch of 25 µm for thermal imaging applications is presented. The IRFPA has a 16-bit digital video data output at a frame rate of 30 Hz. Thousands of Analog to Digital Converters (ADCs) are located under the microbolometer array. One ADC consists of a Sigma-Delta-Modulator (SDM) of 2nd order and a decimation filter. It is multiplexed for a certain amount of microbolometers arranged in a so called "cluster". In the 1st stage of the SDM the microbolometer current is integrated time-continuously. The feedback is applied using a switchable current source. First measurements of Noise Equivalent Temperature Difference (NETD) as a key parameter for IRFPAs will be presented

In this paper we discuss methods to improve the geometric design of microbolometer pixels in uncooled focal plane arrays. For cost reduction reasons, the pixel pitch of these microbolometer elements should be reduced as much as possible while keeping the same level of performance. This becomes increasingly difficult once the dimensions of the microbolometer elements reach a critical value of about 25 micrometers, mainly because the available space limits the thermal isolation and the available area for IR absorption. For these reasons it is essential to optimize not only the material properties but also the geometric aspects of the microbolometer structure to get the maximum performance for a given size of the elements. Extending the work of Liddiard [1], in the first part of this paper we discuss the design of the optical cavity, focussing mainly on the influence of the sacrificial layer thickness, which defines the properties of the resulting Fabry Perot resonator. In the second part of this paper we concentrate on the geometry of the absorbing membrane itself and give estimates for optimum film thickness and lateral dimensions

Purpose: CMOS‐based aSe detectors compared to CsI‐TFT‐based flat panels have the advantages of higher spatial sampling due to smaller pixel size and decreased blurring characteristic of direct rather than indirect detection. For systems with such detectors, the limiting factor degrading image resolution then becomes the focal‐spot geometric unsharpness. This effect can seriously limit the use of such detectors in areas such as cone beam computed tomography, clinical fluoroscopy and angiography. In this work a technique to remove the effect of focal‐spot blur is presented for a simulated aSe detector. Method: To simulate images from an aSe detector affected with focal‐spot blur, first a set of high‐resolution images of a stent (FRED from Microvention, Inc.) were acquired using a 75µm pixel size Dexela‐Perkin‐Elmer detector and averaged to reduce quantum noise. Then the averaged image was blurred with a known Gaussian blur at two different magnifications to simulate an idealized focal spot. The blurred images were then deconvolved with a set of different Gaussian blurs to remove the effect of focal‐spot blurring using a threshold‐based, inverse‐filtering method. Results: The blur was removed by deconvolving the images using a set of Gaussian functions for both magnifications. Selecting the correct function resulted in an image close to the original; however, selection of too wide a function would cause severe artifacts. Conclusion: Experimentally, focal‐spot blur at different magnifications can be measured using a pin hole with a high resolution detector. This spread function can be used to deblur the input images that are acquired at corresponding magnifications to correct for the focal spot blur. For CBCT applications, the magnification of specific objects can be obtained using initial reconstructions then corrected for focal‐spot blurring to improve resolution. Similarly, if object magnification can be determined such correction may be applied in fluoroscopy and angiography.