Dual-channel diffractometer utilizing linear image sensor charge-coupled devices.

Abstract

A position-sensitive dual-channel light diffracometer has been developed to allow the real-time monitoring of light diffraction patterns produced by the myofibrillar sarcomeres of single skeletal muscle fibers and small bundles of fibers during contraction. The diffractometer utilizes two linear image devices to permit the analysis of two or more diffraction lines. The sensors are highly sensitive (1.67×10−4 lux sec), lag-free, self-scanning 256-element charge-coupled devices driven by Schottky and standard TTL logic circuitry at a data transfer rate/element of about 20–400 kHz. Video output from the diffractometer can be displayed directly on an oscilloscope screen or can be connected to an ADC and minicomputer system so that diffraction spectra can be corrected for dark signal and element nonuniformities and displayed on-line by the computer CRT. The computer-evaluated spacing between diffraction lines provides an accurate measure of mean sarcomere length within the muscle, while line shape and width are indicative of the length distribution among sarcomeres. Sarcomere length resolution attainable with the instrument ranges from about 10 to 100 Å at a nominal length of 2.5 μ, depending on muscle-to-sensor spacing and whether one or two channels of the instrument are operated.