A diffractometer using a lateral effect photodiode for the rapid determination of sarcomere length changes in cross-striated muscle

Abstract

A simple method is devised to record rapid sarcomere length changes of muscle fibres using a lateral effect diode. In the standard position the diffractometer records length changes between 1.65 and 3.8 μm, the output being linear 1 V/μm with a frequency response of −3 dB at 1.2 kHz. The absolute error is<0.05 μm between 1.65 and 2.80 μm and <0.1 μm between 2.81 and 3.30 μm. The resolution of length changes is<0.005 μm over the whole range. By varying the detector position the length range can be extended to either side, and spatial resolution can be improved at the expense of length range.