No abstract

An acousto-optic diffraction device is mounted within a polychromator to perform spectral shifting for the purpose of background correction for atomic spectrometry. Controlling the applied frequency to the acousto-optic allows “on-line” and “off-line” spectral observations. Preliminary investigations included characterization of the behavior of the photomultiplier tube (PMT) signal output at various acoustic frequencies and applied powers to verify the applicability of the system. Low-rate (0.1 Hz) frequency modulation was performed to successfully test the applicability of the background-correction system.

A digital micromirror device (DMD) was tested to demonstrate its potential as a multiplexing device for the simultaneous detection of visible electromagnetic radiation. Using a Visual Basic program, four sections of the DMD were illuminated by a light source and each region of mirrors was modulated at different low frequencies (14.92, 20.00, 25.00, and 34.48 Hz). A time-domain, multiplexed signal was collected from the sectors and a Fourier transform was performed on these data. The resulting frequency-domain spectrum showed that signal intensities correlated well with what was expected. Three different times were used to establish the best frequency resolution. Using this calculated frequency resolution, a 16 s scan could allow simultaneous detection of up to 240 emission/absorption wavelengths. Data collected also shows the selectivity of micromirror regions and the ability to choose specific regions of the micromirror plane, which could be valuable for a number of spectroscopic techniques.