Differences

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--- hg [2020/11/16 13:55] – external edit 127.0.0.1
+++ hg [2024/02/08 18:23] (current) – external edit 127.0.0.1
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 ====== HG ======
+=== Mercury Wavelength Calibration ===
+HG is used to accurately locate the 296.728 nm line of the Mercury spectrum, and then adjust the diffraction grating such that the five ozone operational wavelengths fall onto the appropriate exit slits. \\
+The zenith prism rotates to the test lamps (position 0), the iris is opened, FW#1 is rotated to the quartz disk (position 1), FW#2 to ND=0 (position 0).\\
+Following the initial set-up and lamp warm-up, the grating is scanned in the forward and reverse direction and the resulting combined spectrum is compared to a stored spectrum. Corrections to the micrometer position are made, and if the adjustment required is greater than 2 steps (.012nm) then the scan is repeated. A test for the presence of Hg lamp radiation is made prior to the beginning of the scan, and if it is not there, an FR test is done to reposition the micrometers to pre-set initialization values and the test is redone.
 Refer to [[lamp|Lamps]]