Digital data acquisition and analysis of striated muscle diffraction patterns with a direct memory access microprocessor system

Abstract

A microprocessor based data acquisition computing system has been developed to examine dynamic changes in light diffraction patterns from single skeletal muscle fibers. A significant improvement in digital data acquisition rate compared to previous designs has been achieved by utilizing a fast dedicated analog to digital converter and direct memory access data storage. Diffraction patterns from muscle fibers are imaged onto a 256 element charge‐coupled device. The analog output of a full 256 point frame of data may be digitized and stored in 2.2 ms (128 point half frame in 1.1 ms) with a spatial resolution of up to 5.0 nm/sarcomere. This computing system can transfer up to 28 full frames of data as one continuous block directly between the CCD and memory leaving the CPU free for experimental control and closed‐loop processing. The computing system calibrates and analyzes diffraction data under sofware control for sarcomere length, dispersion, and peak intensity. The operation of this data acquisition computing system is superior to previous digital designs with its increased data acquisition rate and to analog designs with its data manipulation, analysis, experimental control, and processing capabilities.