Linear Variable Filters

Linear Variable Filters (LVF) is a band pass filter coating that has been intentionally wedged in one direction. Since the band pass' center wavelength (CWL) is a function of the coating thickness, the peak wavelength transmitted through the filter will vary in the linear fashion in the direction of the wedge. 

LVFs are ideally suited for use in compact, non-dispersive instruments where high-resolution measurements of a spectrum are involved or where information is desired at a number of wavelengths of a specific spectrum. They are physically durable and will withstand the rigors of industrial, military, and aerospace environments.

The LVF coating can be manufactured in any wavelength range from 300 nm to 20 um. The specified wavelength range for a typically LVF is ~2x the beginning wavelength of the filter.  For example, if the starting wavelength of the LVF is 380 nm, the ending wavelength is ~760 nm. The LVF design allows multiple filters to be placed together to provide wavelength coverage greater than a 2:1 spread. The variation of the CWL can be maintained to within + 0.5% of virtually any monotonic function (e.g. linear or logarithmic). The resolution of an LVF is typically specified between 1-2% of CWL. Higher or lower resolutions are possible.

Edge-Bonded Assemblies

Filter, Infrared, Narrow Bandpass

Filter, Linear Variable

Filter, UV/IR Blocking