The development of a data acquisition system for a vacuum-ultraviolet spectroradiometer

An improved vacuum-ultraviolet spectroradiometer has been developed for use in the characterization of rocket plume radiant emission and the study of combustion processes in liquid rocket engines. The system acquires and processes the data so as to display the spectrum in units of volts per pixel. With proper calibration, it will display the spectrum in spectral radiance units of power per unit solid angle per unit source area per unit wavelength.

The spectrometer displays the plume's radiant emission in terms of its electromagnetic spectrum. Two light image intensifier (LII) tubes and two charge- coupled device (CCD) arrays convert the spectrum to an electrical signal and pass the signal on to the electronic hardware. The hardware digitizes the signal and stores the data in a buffer until a computer can transfer it to disk. The computer's software controls the entire operation. Off-line, code reduces the acquired data to engineering units and displays the spectrum on the computer's monitor. This thesis describes the development of the data acquisition system (CCDs, electronic hardware, computer, and software) of the improved spectroradiometer.

The device can monitor a continuous spectral range of 44 nm or two ranges of 22 nm each anywhere in the ultraviolet (UV) spectrum extending from 120 nm to 320 nm. The device can also provide simultaneous spatial-spectral measurements. That is, the charges in each CCD pixel column can be summed as one vertical group with a minimum integration period of 50 ms or the pixel column can be divided and summed in 2, 10, or 20 vertical groups with minimum integration periods of 120 ms, 600 ms, or 1200 ms, respectively.