Near-infrared-ray computed tomography with an 808 nm laser beam and high spatial resolutions

To increase the penetrating photons and to improve the spatial resolution in near-infrared-ray computed tomography (NIR-CT), we used an 808 nm laser module. The NIR photons are produced from the laser module, and an object is exposed to the laser beam. The laser power is controlled by the applied voltage, and the photodiode detects photons penetrating through the object. To reduce scattering photons from the object, a 1.0-mm-diameter graphite pinhole is set behind the object. The spatial resolutions were improved using a 1.0-mm-diameter 5.0-mm-length graphite collimator and were ∼1 × 1 mm². The NIR-CT was accomplished by repeating the object-reciprocating translations and rotations of the object using the turntable, and the ray-sampling-translation and rotation steps were 0.1 mm and 0.5°, respectively. The scanning time was 19.6 min at a total rotation angle of 180°. Triple-sensitivity CT was accomplished using amplifiers, and a graphite rod in the chicken fillet was visible when increasing amplification factor.