Short Wave Infrared (SWIR) Imaging In Machine Vision Princeton Infrared Technologies, Inc. Martin H. Ettenberg, Ph. D. President martin.ettenberg@princetonirtech.com Ph: +01 609 917 3380 Booth Hall 1 J12 1
SWIR Technology Background Short Wave Infrared (SWIR) Imaging Defined from 1000nm 2600nm Near Infrared 750 1000nm (what Si can detect) In x Ga 1 x As, InSb, and HgCdTe is typically used to image in this band InSb and HgCdTe require significant cooling (expensive and heavy) Lattice Matched InGaAs, In.53 Ga.47 As is lattice matched to InP allowing low dark current and low cost imaging Lattice matched InGaAs allows 0.9 to 1.7um typically Ettenberg, M. H., Malchow, D., ShortWave Infrared (SWIR) Imaging Aids laser Tracking, Detection Photonic Tech Briefs, April 2007. http://www.equinoxsensors.com/products/multi spec_faces.html
SWIR uses Reflected and Emitted Light SWIR imagery is typically reflected imagery very similar to visible light Samples can be illuminated in the front and reflected light can be used Samples can be back lit and one can look at the absorption of light. Mid Wave Infrared (MWIR) and Long Wave Infrared (LWIR) cameras use emitted light from the object itself. No external light source is needed. SWIR imaging allows for better resolution because of smaller wavelength and the fact that it uses reflected light versus emitted light. 3
Princeton Infrared Technology has InGaAs imagers sensitive to visible and SWIR SWIR Only Visible and SWIR SWIR only image is illumination only by a hot soldering iron. Visible & SWIR is with fluorescent lights on. Soldering Iron is emitting light in SWIR band while the person is imaged by reflected light from the soldering iron and/or fluorescent light source. 4
SWIR Sensitive to Thermal Also Water heated to 75C Thermal emission in SWIR 90ms integration time Able to image hot water through the glass SWIR imagers can use glass or plastic optics MWIR and LWIR need sapphire or Ge optics which are expensive SWIR Camera Thermal or LWIR Camera http://www.photonics.com/edu/handbook.aspx?aid=25134 5
SWIR Can Detect Water Easily TCE TCE Isopropanol Acetone Water IsopropanolAcetone Water 4 clear liquids in visible are very different in SWIR band Water is very absorbing Utilizing specific wavelengths of light can improve contrast versus broadband. 6
Agricultural Inspection Water detection in Fruit http://www.qualitymag.com/articles/91011 short wave infrared enhancesmachine vision Bruise on fruit is obvious in SWIR but in the visible it is difficult to image Water released from bruise makes it very detectable Many other agricultural applications Shells from nuts Leaves from twigs Dryness of wood 7
Many Plastics are Transparent in SWIR http://www.qualitymag.com/articles/91011 short wave infrared enhancesmachine vision Water in detergent is absorbing Plastic bottle is fairly transparent in SWIR band Plastic sorting is also conducted in SWIR band by looking at reflected signals of different plastics at different wavelengths of light 8
SWIR Images through Silicon Solar Cell or Semiconductor Processing Silicon Wafer is transparent in SWIR but not in visible Allows for detection of defects in processing Enables raw material inspection 9
Multi or Hyper spectral Imaging in Materials have different structures and these structures results in different absorption and reflection of light in SWIR band. Looking at multiple colors of light enables one to differentiate item A form item B Imaging cubes are created by looking at multiple colors simultaneously SWIR 10 Molero, J. et al, J. Appl. Remote Sens. 6(1), Anomaly detection based on a parallel kernel RX algorithm for multicore platforms May 10, 2012.
Human s have different reflective characteristics in SWIR band http://www.upcscavenger.com/wiki/infrared/#page=wiki Hair is highly reflective Skin is very absorbing (water content) Clothing is reflective, some is transparent 11
Underdrawings In Paintings Advanced Imaging, Len Yencharis, Scientific Imaging Extends IR Value April 2004. Many paints are transparent in SWIR enabling users to see charcoal underdrawings. We see many things that are unseen. 12
1280SCICAM 1280SCICAM Gold Level Award from Vision System Design Innovators Award (2016) 1280x1024 12um pitch FPA and Camera <40e read noise 95Hz frame rate at 1280x1024 Windowing allows >750Hz at 320x256 14 bit A/D on chip Camera link output 0.4 1.7 m response at 25C Visible an SWIR response 60C setpoint possible for long integration times (>6 minutes) No image lag at high sensitivity CTIA architecture very high linearity and radiometric response Response can be calibrated 13
LineCam12 Linescan Camera Utilizes our 1024x1 linear array 12.5 m pitch Response from 0.4 1.7 m Two versions LineCam12 12.5 1.7 T and M Spectroscopy T with 250um tall pixels Machine Vision M with 12.5 m tall pixels Features <100e readnoise >30klines/s 14 bit digital output (>6000:1 dynamic range) 75ke to 100Me full well (128 steps) USB3 Vision Compatible and Camera Link Powered by USB3 cables in most applications 14
LineCam12 Features <$10k in single piece quantities USB3 and Camera Link compatible Trigger input F and C and M42 mount adapters Variable Integration time from 30us to >10s 30klines/s in 1024x1 mode Optional power input for higher temperature ranges Non housing versions available upon request 15
PIRT uses Backside illuminated Detectors Several Key Advantages Response from 0.4 to 1.7 m Higher effective QE Double pass on light No wire bonds or bond pads in the way Single ROIC minimizes odd/even effect Enables filters to be placed on the array G. H. Olsen, InGaAs Fills the Near IR Detector Array Vacuum Laser Focus World March 1991. http://www.xenics.com/ sites/default/files/leaflet s/xb 034_02_xlin_detector_s eries_modulescompone nts_lowres.pdf 16
Various Lens and Lighting Options Various Vendors for SWIR optics Optec, Stingray optics, Navitar, Edmund Optics, among others Lighting Options Incandescent lights (broad band) Metaphase makes LED lighting at specific wavelengths 17
Conclusions SWIR has many unique applications in machine vision Many are yet to be found because we can image things that can t be imaged in the visible band. Princeton Infrared Technologies is: ready to provide state of the art InGaAs linear detectors and FPAs for imaging in SWIR ready to provide custom SWIR solutions Work with various vendors for lighting and lens options enabling new applications with SWIR imaging technology. Come visit us at Hall 1 J12. 18