A snapshot multispectral imager with integrated tiled filters and optical duplication

Although the potential of spectral imaging has been demonstrated in research environments, its adoption by industry has so far been limited due to the lack of high speed, low cost and compact spectral cameras. We have previously presented work to overcome this limitation by monolithically integrating optical interference filters on top of standard CMOS image sensors for high resolution pushbroom hyperspectral cameras. These cameras require a scanning of the scene and therefore introduce operator complexity due to the need for synchronization and alignment of the scanning to the camera. This typically leads to problems with motion blur, reduced SNR in high speed applications and detection latency and overall restricts the types of applications that can use this system. This paper introduces a novel snapshot multispectral imager concept based on optical filters monolithically integrated on top of a standard CMOS image sensor. By using monolithic integration for the dedicated, high quality spectral filters at its core, it enables the use of mass-produced fore-optics, reducing the total system cost. It overcomes the problems mentioned for scanning applications by snapshot acquisition, where an entire multispectral data cube is sensed at one discrete point in time. This is achieved by applying a novel, tiled filter layout and an optical sub-system which simultaneously duplicates the scene onto each filter tile. Through the use of monolithically integrated optical filters it retains the qualities of compactness, low cost and high acquisition speed, differentiating it from other snapshot spectral cameras based on heterogeneously integrated custom optics. Moreover, thanks to a simple cube assembly process, it enables real-time, low-latency operation. Our prototype camera can acquire multispectral image cubes of 256x256 pixels over 32 bands in the spectral range of 600-1000nm at a speed of about 30 cubes per second at daylight conditions up to 340 cubes per second at higher illumination levels as typically used in machine vision applications.

[1]  Philip R. Ashe,et al.  Development of a Miniature Snapshot Multispectral Imager , 2010 .

[2]  Colm P. O'Donnell,et al.  Hyperspectral imaging – an emerging process analytical tool for food quality and safety control , 2007 .

[3]  P. Hanrahan,et al.  Light Field Photography with a Hand-held Plenoptic Camera , 2005 .

[4]  Warren D. Smith,et al.  Modern Optical Engineering: The Design of Optical Systems, Fourth Edition , 1966 .

[5]  Liang Gao,et al.  Development of image mappers for hyperspectral biomedical imaging applications. , 2010, Applied optics.

[6]  Haibo Yao,et al.  Differentiation of toxigenic fungi using hyperspectral imagery , 2008 .

[7]  Andrew R. Harvey,et al.  Imaging spectrometry at visible and infrared wavelengths using image replication , 2004, SPIE Security + Defence.

[8]  H. Macleod,et al.  Thin-Film Optical Filters , 1969 .

[9]  E. Ford,et al.  Vegetation's red edge: a possible spectroscopic biosignature of extraterrestrial plants. , 2005, Astrobiology.

[10]  Andrew Lumsdaine,et al.  The focused plenoptic camera , 2009, 2009 IEEE International Conference on Computational Photography (ICCP).

[11]  E. Dereniak,et al.  Compact real-time birefringent imaging spectrometer. , 2012, Optics express.

[12]  Josse De Baerdemaeker,et al.  Hyperspectral waveband selection for on-line measurement of grain cleanness , 2009 .

[13]  Daniel W. Wilson,et al.  Spatial-spectral modulating snapshot hyperspectral imager. , 2006, Applied optics.

[14]  Mitchel D. Horton,et al.  A heuristic technique for CTIS image reconstruction. , 2007, Applied optics.

[15]  Liang Gao,et al.  Snapshot Image Mapping Spectrometer (IMS) with high sampling density for hyperspectral microscopy , 2010, Optics express.

[16]  Ashwin A. Wagadarikar,et al.  Single disperser design for coded aperture snapshot spectral imaging. , 2008, Applied optics.

[17]  M E Gehm,et al.  Single-shot compressive spectral imaging with a dual-disperser architecture. , 2007, Optics express.

[18]  David Laubier,et al.  Study of accessible performances of a spectro imager using a wedge filter , 2008, Optical Systems Design.

[19]  Kazuyoshi Itoh,et al.  Application of Measurement multiple-image fourier of fast phenomena transform spectral imaging to measurement of fast phenomena , 1994 .

[20]  P. Hariharan.  Basics of Interferometry , 2006 .

[21]  B·H·W·亨德里克斯,et al.  Hyperspectral imaging system having a camera probe guide , 2014 .

[22]  Eustace L. Dereniak,et al.  New grating designs for a CTIS imaging spectrometer , 2007, SPIE Defense + Commercial Sensing.

[23]  Scott A Mathews,et al.  Design and fabrication of a low-cost, multispectral imaging system. , 2008, Applied optics.

[24]  Philippe Soussan,et al.  A compact, high-speed, and low-cost hyperspectral imager , 2012, Other Conferences.

[25]  Bernhard P. Wrobel,et al.  Multiple View Geometry in Computer Vision , 2001 .

[26]  Peg Shippert.  Why Use Hyperspectral Imagery , 2004 .

[27]  J. Tanida,et al.  TOMBO: thin observation module by bound optics , 2002, The 15th Annual Meeting of the IEEE Lasers and Electro-Optics Society.