Infrared (IR, 3-12-μm) microscopic spectral imaging is an important analytical technique. Many current instruments employ thermal IR light sources, which suffer the problem of low brightness and high
noise. This paper evaluates the system engineering merit in using semiconductor lasers, which offer orders-of-magnitude-higher power, brightness, and lower noise. A microscopic spectral imaging system using
semiconductor lasers (quantum cascade) as illuminators, and focal plane array detectors demonstrated a high signal-to-noise ratio (>20 dB) at video frame rate for a large illuminated area. The comparative
advantages of laser vs. thermal light source are analyzed and demonstrated. Microscopic spectral imaging with fixed-wavelength and tunable lasers of 4.6-, 5.1-, 6-, and 9.3-μm wavelength was applied
to a number of representative samples that consist of biological tissues (plant and animal), solid material (a stack of laminated polymers), and liquid chemical (benzene). Transmission spectral images with
~30-dB dynamic range were obtained with clear evidence of spectral features for different samples. The potential of more advanced systems with a wide coverage of spectral bands is discussed.
The Society publishes the internationally recognized, peer reviewed journal, Applied Spectroscopy, which is available both in print and online. Subscriptions are included with membership or can be purchased by institutional or corporate organizations. Abstracts may be viewed free of charge. Previously published as Bulletin (Society for Applied Spectroscopy)