Advanced Imaging


Advanced Imaging Magazine

Updated: January 12th, 2011 10:01 AM CDT

NIR-SWIR Imaging: From Health Care to Industrial Applications

InGaAs linear detector arrays help improve medical diagnostics, maximize and speed up machine vision
SD-OCT depth image of high repetition
James M. Fraser, Ph.D., assistant professor, Paul Webster, MScEng candidate, Queen's University, Kingston, Ontario, Canada.
Figure 1 SD-OCT depth image of high repetition rate picosecond laser cutting into steel, with the Y-axis showing a total scale of 500 microns in depth (500 microns depth displayed out of 1300 microns acquired) and the X-axis showing 110 ms of time. The image is supplied courtesy of James M. Fraser, Assistant Professor, Ph.D. and Mr. Paul Webster, MScEng Candidate, both of Queen's University at Kingston (Ontario, Canada).
SD-OCT depth image of high repetition
Steve Woo and Joseph Izatt of Bioptigen
Figure 2 3-D section of a fingertip, with top portion removed. The smaller images on left show 2-D images at the Y and Z planes and are used to select where the 3-D cutaway plane occurs. The image is supplied courtesy of Mr. Steve Woo, Optical Engineer, Bioptigen, Inc. (Durham, NC) and Joseph Izatt, Ph.D., Associate Professor of Biomedical Engineering, Associate Professor of Ophthalmology, Duke University (Durham, NC).
High Speed Digital Line Scan Camera
Figure 3 High Speed Digital Line Scan Camera (SU-LDH) from SUI (Sensors Unlimited Inc.), part of Goodrich and the InGaAs linear photodiode array sensor it uses.

By Doug Malchow, SUI

Imaging technology is rapidly evolving in many arenas, including scientific, industrial, military and security markets. This article will review important research, recent developments in industrial and biomedical shortwave infrared (SWIR) imaging, and new machine vision applications, all of which are enabled by detector linear arrays utilizing indium gallium arsenide (InGaAs).

In the biomedical field, research labs around the world are working to provide doctors with means to image suspicious lesions and to immediately determine tissue characteristics without the need for invasive or surgical biopsy procedures.

High-resolution imaging techniques can aid the process of diagnosing certain diseases without the need for surgical tissue removal and the seemingly interminable wait for lab reports that indicate precancerous, cancerous, atypical or benign growths. A relatively new imaging technique called Optical Coherence Tomography, or OCT can non-invasively provide high-resolution 3D images of biological tissue. First developed in 1989, OCT has found numerous applications for imaging the retina in the eye at high resolution, and more recently, the anterior segment of the eye to diagnose disease and measure structural problems.

OCT systems increasingly are being used to study living tissue with the resolution to see cellular changes that are precursors to cancer's development. By imaging the blood flow in the capillaries near the tissue surface under the suspicious cells, researchers will be able to better gauge malignancy, as the cancer induces the body to supply more nutrients. Researchers in the field refer to these imaging methods as performing an "optical biopsy" or "living biopsy" or "virtual biopsy" as it uses light "in vivo" to probe living tissue, instead of excising and killing cells with a knife or needle.

Currently, if the diagnosis finds atypical cells or worse, surgeons must remove tissue far beyond the boundaries of the lesion, typically half a centimeter, to minimize the possibility of leaving dangerous cells behind. With OCT, they will not have to guess how much tissue to excise—a critical factor when removing tumors in the brain. OCT features the ability to see millimeters into tissue that is opaque to the eye, while resolving features to less than 5 microns in size, thus allowing for a non-invasive biopsy with safe, non-ionizing light.

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