US 5,710,655 A · Cavity thickness compensated etalon filter

Abstract

A cavity thickness compensated etalon filter. A tuning medium is placed in a Fabry-Perot etalon cavity. The index of refraction of the tuning medium varies as a function of voltage applied across the medium. The etalon is formed of two generally flat substrates disposed substantially parallel to one another. Each substrate has a layer of conductive material within the cavity adjacent the substrate. Each substrate also has a layer of reflective material within the cavity adjacent the substrate. At least one layer of reflective material is only partially reflective so as to enable light to pass into and out of the cavity. Liquid crystal material may be used as a tuning medium in the cavity. In the case of liquid crystal material, the etalon also comprises an alignment layer disposed within the cavity adjacent each substrate to pre-order the liquid crystal material. Means are provided for selectively varying the profile of the voltage across the tuning medium so as to compensate for variation in flatness and separation of the etalon substrates. Means are also provided to the render the filter polarization insensitive.

Claims17

Dependent claims

An etalon filter, comprising:

a first, generally flat substrate;
a second, generally flat substrate substantially parallel to said first substrate so as to form a cavity therebetween, said second substrate being substantially transparent to light at a predetermined wavelength;
a first layer of conductive material disposed in said cavity adjacent said first substrate;
a second layer of conductive material disposed in said cavity adjacent said second substrate, said second layer of conductive material being substantially transparent to light at said predetermined wavelength;
a first layer of reflective material disposed in said cavity adjacent said first substrate;
a second layer of reflective material disposed in said cavity adjacent said second substrate, said second layer of reflective material being partially reflective at said predetermined wavelength;
a tuning medium disposed in said cavity, said tuning medium being substantially transparent to light at said predetermined wavelength, the index of refraction of said tuning medium being a function of the voltage applied across said tuning medium;
and
compensation means for enabling a non-uniform voltage profile to be applied across said tuning medium between said first layer of conductive material and said second layer of conductive material.

6 more elements

Dependencies are inferred from the claim text.

Cavity thickness compensated etalon filter

Life of this patent

Cavity thickness compensated etalon filter

Life of this patent

Abstract

Claims17