Filter device for use in wavelength modulation spectroscopic system, has flat optical filter that is positioned in transparent portion with through-hole so that filter is enclosed by device along main portion of its periphery

摘要

The device has an upper filter gear (1) that is attached with three impellers (4a-4c) which are rotated in a groove along the periphery of the filter gear. The filter gear has a rotational axis around which it is free to rotate. A flat optical filter (3) is positioned in the transparent portion with a through-hole so that the filter is enclosed by the device along main portion of its periphery. An independent claim is included for wavelength modulation spectroscopic system.