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Circular Variable Filters

In addition to their well-known line of Continuously Variable Filters Delta Optical Thin Film A/S now also offers Circular Variable Filters. These are interference narrow bandpass filters of advanced design, which are deposited on circular substrates, called segments. Film thickness, and therefore the wavelength of peak transmittance varies linearly and continuously with angular position on the segment. The filters are ideally suited as monochromators in compact, non-dispersive spectrometers or with supercontinuum lasers, providing medium spectral resolution, or when information is desired at several specific wavelengths in the relevant spectral range.

A Circular Variable Filter can be manufactured in any wavelength range from 400 nm in the visible up to 14.3 µm in the infrared. The specific wavelength at which the radiation is transmitted by the segment is selected by appropriately positioning it on the optical beam. Segment rotation, in a way that the beam traces a circumferential path on it, provides a continuous scan of its complete wavelength range. A spectral resolution element size on the CVF varies between one and two millimeters. Each of the in total seven segments spans 90°. Four segments can be mounted on a pre-balanced wheel, that can be rotated by a USB connected controller.More products