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Circular Variable Filter

CI Systems’ Circular Variable Filter (CVF) is an interference narrow-pass filter of advanced design which is 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. A Circular Variable Filter is ideally suited as monochromators in compact, non-dispersive spectrometers, allowing medium and high resolution spectral radiation measurements, or when information is desired at a number of specific wavelengths in the relevant spectral range.


For more information
Microscopy app.Key FeaturesSpectral Ranges

A Circular Variable Filter can be implemented on the illumination channel of a brightfield microscope (integrated into the condenser) or, on the exit imaging port of the microscope (brightfield or fluorescent applications). A CVF-based microscope will insure reliable measurement of a live-cell specimen and of stained or hybridized samples. 

Key features

  • Uniform transmission >50% throughout the spectral range
  • Out-of-band blocking < 0.1%  of peak transmission
  • Spectral resolution <2% of wavelength
  • Covers the entire VIS-NIR range
  • Non-polarizing
  • Does not require any periodical calibration
  • Allows for fast wavelength switching
  • Not limited in angle of incidence
  • Does not degrade over time
  • Compact in size


  • Full wavelength scanning from visible to long wave IR.
  • Successive discrete wavelength selection in the range of the segment.
  • Allows instrument design flexibility and versatility.
  • High volume manufacturing.

All in µm

  • 0.4 - 0.675
  • 0.6 5 - 0.95
  • 0.9 - 1.35
  • 1.3 - 2.5
  • 2.4 - 4.6
  • 4.3 - 8.1
  • 7.7 - 14.3
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