Coded aperture imaging in high energy astronomy software

Codedaperture imagers extend the pinhole camera concept, which requires no lenses, has unlimited depth of focus, and can image radiation of any wavelength. Hard xray and lowenergy gammaray codedaperture imaging instruments have been highly successful as highenergy surveyors. Mask enhanced cameras for heterodyned light fields and coded aperture refocusing. A mask consisting of an array of opaque and transparent elements set between the source fluxes and a positionsensitive detection plane is employed for image formation. In this paper, we present a nearfield ca imaging technique and image reconstruction method for high sensitivity and high resolution single photon emission computerized. The former provides realtime, highresolution imaging of nearsurface objects, while the latter provides highsensitivity, moderate resolution of deep objects. An alternative technique to do imaging in this spectrum is to use classical.

Pdf coded aperture imaging in x and gammaray astronomy. Veeraraghavan, raskar, agarwal, mohan, and tumblin. To support the development of the next generation of coded aperture telescopes, a software facility has been developed to simulate the response of any maskdetector configuration and the observation of various photon sources, allowing its sensitivity and imaging properties to. Coded aperture snapshot spectral imaging cassi provides an efficient mechanism for recovering 3d spectral data from a single 2d measurement. Cannon, coded aperture imaging with uniformly redundant arrays, applied optics, vol. Coded apertures allow highenergy xray phase contrast. Pdf on the properties of images from coded mask telescopes. In this paper we propose a novel dualcamera design to improve the performance of cassi while. Coded aperture ca imaging originally developed in xray astronomy has not been widely used in nuclear medicine due to the decoding complexity of nearfield ca images. Osa programmable liquid crystal display based noise. Coded aperture imaging is now a standard technique in high energy astronomy. Techniques of coded aperture imaging for gammaray astronomy. Scintillator based codedaperture imaging has proven to be effective when applied for x and gammaray detection.

G cocco an almost complete collection of the papers given at the international workshop on imaging in high energy astronomy anacapri, italy, 1994. Due to limitations in the used source, we show images acquired at tube voltages of up to 100 kvp, however, no intrinsic reason indicates that the method could not be extended to even higher. A combined compton and codedaperture telescope for. Mercuric iodide xray camera for high energy astronomy w. For the possible chinese solar mission in the near future, we make a design of hard xray imaging telescope, and simulate the photon counting using the common simulation software geant4.

Sourcesearch sensitivity of a largearea, codedaperture. Simulation research on the solar hard xray imaging telescope. This page is based largely on the article new family of binary arrays for coded aperture imaging by stephen r. It is an ideal technique for high energy astrophysics because it has high throughput, excellent performance on point sources, and the ability to measure simultaneously signal and background. Coded aperture imaging with uniformly redundant arrays uras is the standard technique for imaging above the limit of grazing incident xray telescopes. The text is regularly updated for new developments in the field. The several snapshots are combined together with appropriate weightings to form a single equivalent frame as are the aperture functions for the coded aperture arrays used. Compressive imaging spectrometers using coded apertures d. Us8073268b2 method and apparatus for coded aperture. In 1996, a highresolution positionsensitive he3 proportional counter was used in a cdlined box to construct a coded aperture imaging device with an 11 x tjra mask. Coded aperture imaging in high energy astronomy represents an. Imaging in high energy astronomy proceedings of the international workshop held in anacapri capriitaly, 2630 september 1994. To support the development of the next generation of coded aperture telescopes, a software facility has been developed to simulate the response of any maskdetector configuration and the observation of various photon sources, allowing its sensitivity and imaging properties to be evaluated. The ibis telescope onboard integral, the esa gammaray space mission to be launched in 2002, is a soft gammaray 20 kev 10 mev device based on a coded aperture imaging system.

Coded aperture camera imaging concept c jean in t zand, 1992, 1996. Improvements in coded aperture thermal neutron imaging. These proceedings, which concentrate on imaging above 10. The goal of hyperspectral imaging is to obtain the spectrum for each pixel in the image of a scene, with the purpose of finding objects, identifying materials, or detecting processes. This paper appeared in a longer version in in t zand 1992. Imaging in high energy astronomy proceedings of the. Proceedings of the international workshop held in anacapri capriitaly, 2630 september 1994. The spatial modulation telescope is the telescope which keeps its central axis not rotate, suitable for the satellite of 3axis attitude stabilization. Gammaray imaging with the coded mask ibis telescope. The wavelengths are usually high energy radiation such as xrays and gamma rays. Additionally, localization of two 511 kev point sources separated by 0. The sensitivity for line sources and a continuum source is estimated based upon the expected background in a lowearth orbit. It took place at the hci heidelberg university during the summer term of 20. Coded apertures or coded aperture masks are grids, gratings, or other patterns of materials opaque to various wavelengths of electromagnetic radiation.

We describe here basic concepts of coded masks, the imaging system of the ibis telescope, and the standard data analysis procedures to reconstruct sky images. Fast decoding algorithm for gourlayyoung coded apertures. Instrument description and performance first author. In this paper, we adapt confocal imaging to largescale scenes by replacing the optical apertures used in microscopy with arrays of real or virtual video projectors. Data analysis software for the ibispicsit high energy.

Synthetic aperture confocal imaging acm transactions on. However, since the reconstruction problem is severely underdetermined, the quality of recovered spectral data is usually limited. This work analyzes the performance of the codedaperture based xray phase contrast imaging approach, showing that it can be used at high xray energies with acceptable exposure times. Highrank coded aperture projection for extended depth of field chenguang ma1, jinli suo1, qionghai dai1, ramesh raskar2, gordon wetzstein2 1department of automation, tsinghua university, 2mit media lab abstract projectors require large. Aperture collimation correction and maximumlikelihood. And, finally, as shown in figure 4, the combination of optical imaging color video and nir fluorescence and coded aperture radioscintigraphy appear to complement each other. An almost complete collection of the papers given at the international workshop on imaging in high energy astronomy anacapri, italy, 1994. Coded aperture imaging in x and gammaray astronomy coded aperture imaging in high energy astronomy represents an important technical advance in instrumentation over the full energy range over xrays till gammarays and is playing a unique role in those spectral ranges where other techniques become ineffective or impracticable due to. Highlight potential improvements to codedaperture neutron imaging systems. Several snapshots of an image are acquired, each using a different coded aperture array. The instrument was constructed to verify that weak point sources can be detected at considerable distances if one uses imaging to overcome fluctuations in the natural background.

These proceedings, which concentrate on imaging above 10 kev, represent the state of the art in the field, resulting from the. Compressive imaging spectrometers using coded apertures. Both these instruments use the same coded aperture mask in order to create images of the sky over the entire energy range with a resolution of 12 arcminutes and point source location accuracy down to tens of arcseconds for the strongest sources. Adaptation of the same method for neutron imaging has resulted in a number of propitious systems, which could be potentially employed for neutron detection in security and nuclear decommissioning applications.

Codedaperture imaging was introduced by dicke 1 and ables 2 in the 1960s, and the field developed rapidly for astronomical xray and gammaray imaging. A mura coded aperture was implemented using laser ablation by. In gammaray high energy imaging, coded masks are used as aperture masks scattering the incoming gamma photons. Integral is dedicated to the fine spectroscopy ee 500 and fine imaging angular resolution. That first balloon flight succeeded in imaging gammarays from both the crab pulsar and the black hole binary system cygnus x1. Most cai methods reconstruct target image only from a singleshot coded image using a fixed coding mask. Dgt represented the first time that a technique called coded aperture imaging was applied to gammarays from space. Focusing of highenergy radiation is sofar technically feasible only for photon energies up to about 10 kev through grazing incidence reflection aschenbach 1985. Methods for coded aperture imaging, and processing the data from coded aperture imaging are taught.

At energies above 30 kev, the only available detector system with high detection efcienc y is the scintillation. Coded aperture imaging imaging using highenergy radiation with a spectrum ranging from xray to. Data analysis software for the ibispicsit highenergy detector on integral foschini, luigi. Additionally, a telescope must have good efficiency and a high sensitivity to detect and. Coded aperture imaging in high energy astronomy represents an important technical advance in instrumentation over the full energy range from x to. A combined compton and codedaperture telescope for medium. Coded aperture imaging is a known imaging technique which is primarily used in high energy imaging such as xray or. Hyperspectral imaging, like other spectral imaging, collects and processes information from across the electromagnetic spectrum. In coded aperture imaging, the way the mask is designed is likely to simulate incoherent projections.

This imager was shown to be capable of locating a thermal neutron source within one pixel at distances up to 65 meters. By blocking radiation in a known pattern, a coded shadow is cast upon a plane. A postscript version of the complete paper original version, without figures is available 220 kb. Besides traditional lensbased imaging techniques, coded aperture imaging cai can also provide target images but without using any optical lenses, therefore it is another solution in imaging applications. Coded aperture imaging in high energy astronomy represents an important technical advance in instrumentation over the full energy range from x to rays and is playing a unique role in those. Confocal microscopy is a family of imaging techniques that employ focused patterned illumination and synchronized imaging to create crosssectional views of 3d biological specimens.

Optimization of coded aperture radioscintigraphy for. A future mission in mediumenergy gammaray astrophysics would allow for many. Pdf gammaray imaging with the coded mask ibis telescope. It is a coded aperture imaging instrument with a 1. New family of binary arrays for coded aperture imaging. Abstractwe have recently completed a largearea, codedaperture, gammaray imager for use in searching for radiation sources. The best imaging technique currently in use in the hard xray and gammaray region is the use of coded aperture mask along with a position sensitive detector. Introduction the technique of coded aperture imaging of celestial sources of high energy emission is enjoying increasing popularity in the soft and hard xray domains with the results from the spacelab 2 mission 1, the recent commencement of the operational phase of the sigmagranat telescope which with an upper energy threshold of 1. An excellent web site on the topic can be found at coded aperture imaging in highenergy astronomy, which also has an extensive bibliography. The burst alert telescope bat is a highly sensitive, large fov instrument designed to provide critical grb triggers and 4arcmin positions. Random mask optimization for fast neutron coded aperture.

A directional detector for gammaray astronomy has been developed to image sources in the energy range 0. Imaging using highenergy radiation with a spectrum ranging from xray to. Coded apertures are used in x and gamma ray imaging systems, because these highenergy rays cannot be focused with lenses or mirrors that work for visible. Gehm duke university fitzpatrick center for photonics, durham, nc, 27708 abstract a spectral imager provides a 3d data cube in which the spatial information 2d of the image is complemented by spectral information 1d a bout each spatial location. It is an open source software package that was designed for use with. Highrank coded aperture projection for extended depth of. Coded aperture imaging in x and gammaray astronomy. Pdf coded aperture imaging in high energy astronomy represents an important technical advance in instrumentation over the full energy range from x to. Lensless codedaperture imaging with separable doubly. More formally, the couple coded aperture mask and detector field is equivalent to selecting some projections in the fourier space. An array of 35 gain stabilized bismuth germanate detectors, together with a coded aperture mask based on a uniformly redundant array allows imaging in 4 deg square sky bins over a 16 x 24 deg fieldofview.

Lattice pseudorandom arrays and nextgeneration coded. Testing and simulation of silicon photomultiplier readouts for scintillators in highenergy astronomy and solar physics. Scintillator based coded aperture imaging has proven to be effective when applied for x and gammaray detection. The codedaperture imaging technique is then applied to these selected. Coded aperture imaging concept astrophysics science division. Dualcamera design for coded aperture snapshot spectral. Testing spi imaging of highenergy and extended sources. In these wavelengths, imaging using lenses is not possible since the rays cannot be refracted or reflected, and hence cannot be focused. An excellent web site on the topic can be found at coded aperture imaging in high energy astronomy, which also has an extensive bibliography. The energy range is 15150 kev for imaging with a noncoded response up to 500 kev.