Simple thermal imaging system based on hollow glass waveguides or silver halide fibers as scanning elements for medical applications

Abstract

A simple thermal imaging system based on silver halide fibers or glass hollow waveguides was constructed. The proximal end of each type of waveguide was fixed and attached to an infrared detector. The distal end of each waveguide was scanning in two directions. Such a device was used to construct a simple imaging system. The thermal image of a warm object may be formed at the focal plane of an infrared lens. The distal end of each waveguide scanned the image. The infrared radiation was transmitted through the waveguide to the detector. The signals from the detector were coupled into a suitable monitor that produced a representation of the thermal image. In preliminary experiments we used an unclad silver halide fiber of diameter 0.7 mm, and a hollow glass waveguide of diameter of 0.5 mm. A permanent magnet was attached to the end tip of each waveguide, and it was displaced by a varying electro magnetic field. The detector used was a room temperature pyroelectric detector. A MTF of about 0.2 at a spatial frequency of 1.25 cycles/mm, and a MRTD of 0.50 Celsius deg at 0.1 cycles/mm were obtained with this simple imaging system.