Abstract we report terahertz codedaperture imaging using photoinduced reconfigurable aperture arrays on a silicon wafer. By blocking radiation in a known pattern, a coded shadow is cast upon a plane. Coded aperture imaging in high energy astronomy represents an important technical advance in instrumentation over the full energy range from x to. Static 2d aperture coding for multimodal multiplex spectroscopy. Czt detector, depth sensing, hard xray imaging, codedaperture, radial. Optical imaging and spectroscopy wiley online books. Compressive imaging spectrometers using coded apertures. Terahertz imaging, coded aperture, vanadium dioxide, bowtie array, re ection coe cient measurement, circuit model, transmission simulation 1. A codedaperture spectrograph combined with compressive imaging algorithms will allow for widearea interrogation with fast acquisition rates. Transmittance analysis in coded aperture compressive raman.
Multimodal multiplex raman spectroscopy optimized for in. An introduction imaging spectroscopy involves the sensing of a large amount of spatial information across a multitude of wavelengths. We have positions avaialble for undergrad and masters students please contact jason. Coded apertures or codedaperture masks are grids, gratings, or other patterns of materials opaque to various wavelengths of electromagnetic radiation. The evolution of codedaperture spectroscopy optics. In imaging spec troscopy, these scalar values are replaced with a vector containing the spectrum spectral information from that spatial location. Assuming the coded aperture moves linearly during d t such that stnt, the images temporal spectrum is. Codedaperture duv spectrometer for standoff raman spectroscopy. This article surveys compressive coded aperture spectral imagers, also known as coded aperture snapshot spectral imagers cassi 1, 3, 4, which naturally embody the principles of compressive sensing cs 5, 6. Figure 6b shows a comparison of experimental and simulated spectra of a mixture of 50% argon and 50% dry air using a s11 coded aperture with a 50. Request pdf coded aperture spectroscopy with denoising through sparsity we compare noise and classification metrics for three aperture codes in dispersive spectroscopy.
In order to overcome these issues, hadamard spectroscopy hs was implemented in a conventional ebert fastie type of spectrometer setup, by substituting the exit slit with a digital micromirror device dmd who acts like a coded aperture. Osa coded aperture raman spectroscopy for quantitative. Modern coded aperture spectrometers that utilize multichannel detectors require only one coded aperture and are often referred to as static, multimodal, and multiplex spectrometers. Coded aperture and tomographic imaging sampling and transformations in optical systems, including wavelets and generalized sampling techniques essential to digital system analysis geometric. Sensitivity of coded aperture raman spectroscopy to analytes. Introduction of a multihole mask improves the snr while maintaining a good angular resolution of a small diameter, single hole imaging device dicke, 1968. In 2014 ieee nuclear science symposium and medical imaging conference, nssmic 2014. A large energy spectrum of neutron events complicates the employment of the codedmask. Coded aperture spectroscopy with denoising through. Czt detector modeling for coded aperture xray diffraction imaging applications. Ion strike distance in a 90 degree magnetic sector is a function of the radius of curvature of the charged particle in a magnetic field, as well as the height of the imaging.
While static coded apertures are easier to realize and less expensive, adaptive coded apertures are more effective. Proof of concept coded aperture miniature mass spectrometer. Spectral preprocessing in order to combine the spectra for the dierent excitation wavelengths, a calibration sample of acetaminophen. Pdf we introduce a multiple order coded aperture moca spectrometer. This reduction in the area of the aperture limits the amount of light available for detection and adversely affects system sensitivity. Lwir coded aperture dispersive spectrometer university of arizona. Sullivan2 1 duke university, fitzpatrick institute for photonics and department of electrical and computer engineering. To measure accurate wavelengths of emission and absorption lines.
Reliance on single detectors required mechanical, electrooptical, liquid crystal, or other forms of modulation to read spectral data. This is a common problem in spectroscopy applications that can be overcome by introducing a coded aperture at the input that can be computationally inverted to generate a unique response for each spectral. Camms is a redefinition of the miniature mass spectrometer combining microfabrication with concepts such as spatially coded apertures from compressive sensing. Coded aperture raman spectroscopy for quantitative measurements. This article traces the history of this type of spectroscopy, from the earliest analog forms to the latest technology.
This project is a rst step towards the development of a full coded aperture imaging system operating at wr1. We have designed and constructed a coded aperture spectrometer for use in the deep uv range. Coded aperture spectrometers have enabled highspeed applications that were once considered impractical with traditional slit devices. Coded aperture magnetic sector mass spectrometry department. Codedaperture imaging using photoinduced reconfigurable. Weikle iia auniversity of virginia, department of electrical and computer engineering, charlottesville, va 22904 u. Both approaches significantly improve depthoffield through inverse light filtering when compared to circular aperture stops. This paper appeared in a longer version in in t zand 1992. The moca is a system that uses a multiplex hologram and a coded aperture to.
Scintillator based coded aperture imaging has proven to be effective when applied for x and gammaray detection. Coded aperture spectroscopy allows for sources of large e. Terahertz coded aperture mask using a vanadium dioxide. For the first 40 years of coded aperture spectroscopy, coded aperture spectroscopy instruments were limited to single optical detector elements or small arrays of discrete detectors. Furthermore, illconditioned codes with a regularized estimation strategy are shown to perform competitively with wellconditioned codes. Coded aperture raman spectroscopy for quantitative. In contrast with previous theory, we show that multiplex codes may be advantageous even in systems dominated by poisson noise. Optical imaging and spectroscopy by brady, david j.
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 spectrometers have enabled highspeed applications that were once considered impractical with traditional slit devices. Raman spectroscopy has completed its transformation into a fully portable technique for field analysis. Optical imaging and spectroscopy download ebook pdf. Polycapillary focusing elements 1 are frequently used in xray analysis for chemical mapping 2, microimaging 3, depth profiling 4 and xray spectroscopy 5. Optical imaging and spectroscopy ieee signal processing society. This article traces the history of this type of spectroscopy, from the earliest analog forms to. The full text of this article hosted at is unavailable due to technical difficulties. Mms raman spectrometer united states naval academy. The czernyturner design provides sufficient spectral resolution to observe raman scattering features, while the use of a coded aperture provides a greatly improved light collection efficiency for scattering sources. Osa coded aperture spectroscopy with denoising through sparsity. A class of aperture coded spectrometer is optimized for the spectral characterization of diffuse sources. Terahertz coded aperture mask using a vanadium dioxide bowtie. In practice, it is necessary to take into account the various optical artifacts and nonideal characteristic of the optical system.
The coded aperture was implemented using programmable illumination from a commercially available digital light processing projector. Implementation of hadamard spectroscopy using moems as a. Stateoftheart solutions enhance spatial resolution signi. Spectroscopy with pixelated cdznte gamma detectors experiment versus. The codedaperture approach for radiation detection has its roots in development of scatterhole cameras for x and gammarays.
Hyperspectral imaging, like other spectral imaging, collects and processes information from across the electromagnetic spectrum. Highlight potential improvements to codedaperture neutron imaging systems. We introduce a multiple order coded aperture moca spectrometer. One may analyze the expected temporal resolution of the coded data by considering the fourier transform of eq. Despite the availability of these high quality twodimensional electronic detector arrays, coded aperture instruments combining entrance and exit coded apertures for twodimensional codes are still in use today, as described, for example in shlishevsky, v. Pdf multiple order coded aperture spectrometer researchgate. Aug 04, 2011 coded aperture camera imaging concept c jean in t zand, 1992, 1996. In practice, it is necessary to take into account the various optical artifacts. Early highresolution spectroscopy was inefficient and time consuming. Coded aperture camera imaging concept c jean in t zand, 1992, 1996.
Brady is the architect of numerous computational imaging and spectroscopy systems, including multimodal multiplex spectroscopy and coded aperture snapshot spectral imaging. Coded aperture imaging in x and gammaray astronomy. Static twodimensional aperture coding for multimodal. University, where he directs the duke imaging and spectroscopy program. Centices scientists and engineering teams work with a network of partners to answer emerging business and public service needs. Spatial aperture coding techniques have been used in optical spectroscopy to achieve large increases in signal intensity without compromising system resolution. Optical imaging and spectroscopy ieee signal processing. A mask 102 receives light 104 from a light source not shown and selectively passes the light 104 through a plurality of slits 106 to a collimating lens 108 which refracts the light 104 into parallel rays. A novel electric sector lens system was designed to stigmate high.
The wavelengths are usually highenergy radiation such as xrays and gamma rays. The text is regularly updated for new developments in the field. The theory behind hs and the functionality of the dmd are presented. The instrument achieves high throughput and high spatial resolution by replacing the slit of conventional dispersive spectrometers with a spatial filter or mask. Single disperser design for coded aperture snapshot spectral. Antenna phase error compensation for terahertz codedaperture.
The relay optics relay the image from the plane of the coded aperture to the detector through the. 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. We describe a coded aperture spectrometer optimized for raman spectroscopy of diffuse sources, e. Coded aperture spectroscopy with denoising through sparsity. The sensing matrix a thus couples h with the representation basis w. We provide design details of the raman system, along with quantitative estimation results for ethanol. The coded aperture is considered binary, and the dispersive element is considered linear. Coded aperture spectroscopy allows for sources of large etendue to be efficiently coupled into dispersive spectrometers by replacing the traditional input slit with a patterned mask. Request pdf compressive coded aperture spectral imaging. Brady, coded aperture raman spectroscopy for quantitative measurements of ethanol in a tissue phantom solution, appl.
Longwave infrared lwir coded aperture dispersive spectrometer c. Osa coded aperture spectroscopy with denoising through. Coded apertures or coded aperture masks are grids, gratings, or other patterns of materials opaque to various wavelengths of electromagnetic radiation. Us7301625b2 static twodimensional aperture coding for. His current work focuses on multiple aperture lens system design and optical coherence measurement. The imaging optics image the scene onto the coded aperture.
Sensitivity of coded aperture raman spectroscopy to. Single disperser design for coded aperture snapshot. A postscript version of the complete paper original version, without figures is available 220 kb. Coded aperture spectroscopy allows for sources of large tendue to be efficiently coupled into dispersive spectrometers by replacing the traditional input slit. It presents the foundations of computational optical sensor design with a focus entirely on digital imaging and spectroscopy. Xray codedaperture telescopes employing a large area of tungsten mask. Experimental results validate the performance of the instrument. To measure the relative strengths andor equivalent widths of emission or absorption lines.
Optical imaging and spectroscopy download ebook pdf, epub. Coded aperture magnetic sector mass spectrometry core. We compare noise and classification metrics for three aperture codes in dispersive spectroscopy. In mathematical terms masks were represented as binary arrays with the ones corresponding to the pinholes, and. Forensic and homeland security applications of modern. Optical imaging and spectroscopy wiley online library. Proceedings of spie the international society for optical engineering, 7319. In traditional slit spectrometers, the slit width set the. Terahertz coded aperture mask using a vanadium dioxide bowtie antenna array souheil nadria, rebecca percya, lin kittiwatanakulb, alex arsenovicc, jiwei lub, stu wolfb, robert m.
The coded aperture modulates the spatial information over all wavelengths in the spectral cube with the coded pattern. Mar 21, 2017 polycapillary focusing elements 1 are frequently used in xray analysis for chemical mapping 2, microimaging 3, depth profiling 4 and xray spectroscopy 5. The s11 aperture has an ideal throughput increase of 6. Pdf codedaperture raman imaging for standoff explosive. Compressive imaging spectrometers using coded apertures d.
We used the co57 gammaray point source, which emits 122 kev photons. Mms raman spectrometer a product installation and operation manual document number 00040000020906 offices. Coded aperture duv spectrometer for standoff raman spectroscopy. 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. A number of masks can be used including harmonic masks, legendre masks, and hadamard masks. Implementation of a coded aperture imaging system for. The coded aperture approach for radiation detection has its roots in development of scatterhole cameras for x and gammarays. Antenna phase error compensation for terahertz coded. I odinaka, y kaganovsky, ja osullivan, dg politte, ad holmgren, ja greenberg, l carin, and dj brady.