As an offshoot of hyperspectral imaging, which typically acquires tens to slightly more than 100 spectral
bands, ultraspectral imaging, with typically more than 1000 bands, provides the ability to use molecular or
atomic lines to identify surface or airborne contaminants. Surface Optics Corporation has developed a very
high-speed Fourier Transform Infrared (FTIR) imaging system. This system operates from 2 μm to 12 μm,
collecting 128 ×128 images at up to 10,000 frames-per-second. The high-speed infrared imager is able to
synchronize to almost any FTIR that provides at least mirror direction and laser clock signals. FTIRs rarely
produce a constant scan speed, due to the need to physically move a mirror or other optical device to
introduce an optical path difference between two beams. The imager is able to track scan speed jitter, as
well as changes in position of the zero path difference (ZPD) position, and perform real-time averaging if
desired. Total acquisition time is dependent on the return stroke speed of the FTIR, but 16 cm-1 (1024
point) spectral imagery can be generated in less than 1/5 second , with 2 cm-1 (8192 point) spectral imagery
taking proportionately longer. The imager is currently configured with X-Y position stages to investigate
surface chemistry of varied objects. Details of the optical design, focal plane array, and electronics that
allow this high-speed FTIR imager to function are presented. Results of using the imager for several
applications are also presented.
Recently, Surface Optics Corporation has designed and manufactured a field portable bidirectional reflectometer that measures the bidirectional reflectance of samples in place without the need to take samples into the laboratory. The instrument consists of a measurement head, power supply box, and a PC. The measurement head weighs approximately sixty pounds and it contains the source, detector, stepper motors for varying the incident and reflected angles, and a filter wheel. All of these components are software controlled for measuring the BRDF of samples from 400 nm to 1100 nm (VIS-NIR configuration) or 3.0 micrometer to 12.0 micrometer (IR configuration) at incident polar angles of 0 to 60 degrees. The detector can map the BRDF of a sample from 0 to 85 degrees polar angle and 0 to 180 degrees in azimuth. The instrument configuration is reviewed and measured data presented on a blue krylon paint sample.
This paper presents a description of a fully automated, computer-controlled hemispherical directional reflectometer (HDR). It fills the need in many fields of research and development for a device with HDR measurement capabilities which is state-of-the-art in wavelength coverage to 25.0 micrometers and higher, angular polarization resolved coverage 20 to 80 degree(s), partition of reflected radiation into specular and scattered components, and scattered transmittance. This performance is made possible using an 18' major axis electroformed gold-plated specular hemiellipsoid with a 1.8' foci separation. The radiance throughput to the FTIR of this design exceeds by a factor of more than 200 that of the usual diffuse gold integrating spheres. Derived data, based on reflectance and using provided software, includes the IR component of solar absorptance, the index of refraction n and k for dielectrics and conductors for Fresnel materials, and both directional and hemispherical emittance.
Commonly used methods of developing paints and evaluating their performance involve calculating the signatures of vehicles and backgrounds, this requires experimental determination of the directional and bidirectional reflectance of the surfaces involved. This paper describes the measurements required, the instruments used to make such measurements, and computer codes and techniques used for paint development and signature evaluation. Examples of bidirectional reflectance data obtained using full experimental mapping are presented. Applications of BRDF data in IR paint development are demonstrated with emphasis on validation and confirmation of computer modeling codes. Calculations of signatures using BRDF data are given using bidirectional reflectance data for two different coatings.
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