The 137 Series Optical Thickness Gauge from Bristol Instruments is a non-contact instrument designed to accurately and reliably measure the absolute thickness of a variety of transparent, translucent, and some visually opaque materials. The thickness gauge utilizes interferometer-based wavelength meter technology, and includes a super-luminescent LED (SLED), an interferometer assembly, and a digital processor, all housed within a single chassis. The system also comes with an optical probe, a fiber-optic patch cord, and Bristol’s Opti-Cal software.