Optical diffraction intensity of computer-simulated muscle fibers

A computer program which calculates the Fraunhofer diffraction intensity of a simulated skeletal muscle fiber is described. The intensity calculation contains several adjustable parameters. Some of the parameters are related to the myofibrillar arrangement within the muscle fiber and the angle of incident light. The variations of the left and right first-order diffraction intensities with different incident angles are determined. Their profiles exhibit features related to Bragg reflections from planes formed by the myofibrils. The calculations provide the relationship between the observed intensity profile and the myofibrillar arrangement in a real muscle fiber.