Knowledge Bank

In methods of photographic spectroscopy there is a need for precision measurement of a large amount of experimental data -- the positions and intensities of rotational lines, vibrational band heads, and calibration lines, on the photographic; plate. Microdensitometers and optical comparators permit one to measure the positions or sharp features with a precision of 1-2 $\mu m$: however the procedure of measuring, recording, and logging the data for further computer processing can be very tedious and time consuming. if done manually. To expedite this aspect of our work, we have designed and built a cheap($\sim$ $2500, microcomputer included) control interface, by means of which a TRS-80 Model III microcomputer controls the motion of the plate on a microdensitometer and logs the optical density in digital form. In this paper we discuss various aspects of the interfacing task, including hardware and software for stepping motor control, analog-to-digital conversion, and extraction of line positions from the recorded data.