Spectrometer specifications

Polychromator

A high-energy (f/6.7) echelle-based polychromator utilizing two SCD detectors, wavelength range of 163-782 nm. The measured resolution of the system is 0.006 nm at 200 nm. The 80 by 160 mm echelle grating has 79 lines per mm and a blaze angle of 63.4 degrees. A UV disperser incorporates Schmidt correction to eliminate aberration for the 400-mm radius camera sphere. The entire optical system is enclosed in a purged and thermostatted optical enclosure. The optical enclosure is mounted on the same large optical bench as the sample-introduction system. The optical bench is shock-mounted to the frame of the instrument so that normal floor vibrations do not affect system performance. Viewing of the plasma is accomplished by computer control of a mirror located in the optical path and allows selection of axial, radial or mixed viewing modes and adjustment of the plasma viewing in both the vertical and horizontal planes. The viewing position can be optimized by the software. The computer-controlled, pneumatically operated shutter automatically opens and closes for each sample, protecting the first transfer mirror from long exposures system to the intense UV radiation of the plasma, extending the useful lifetime of the mirror. A mercury lamp is built into the shutter mechanism and can be viewed at a user selected frequency to automatically update the system wavelength calibration at the 253 nm mercury emission line.

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