Measurements of the Thickness Uniformity of Liquid Crystal Layer

Optical inspection of liquid crystal variable retarder inhomogeneities

“…Interferometric methods, such as a polarization based interferometer [19], Mach-Zehnder interferometer [20], or holographic based techniques as in [21][22][23], have been used for qualitative evaluation of the flatness distortion of LC based devices and, therefore, of the retardance inhomogeneity. The objective of [19][20][21][22] is to compensate the phase distortion introduced by a pixelated LC device in order to use it in coherent optical processing techniques.…”

“…The objective of [19][20][21][22] is to compensate the phase distortion introduced by a pixelated LC device in order to use it in coherent optical processing techniques. These kinds of compensation are not applicable to monopixel devices, such as LCVRs, or are impractical in high-quality, diffraction-limited imaging systems in which these LCVRs are to be used.…”

“…These kinds of compensation are not applicable to monopixel devices, such as LCVRs, or are impractical in high-quality, diffraction-limited imaging systems in which these LCVRs are to be used. In [19], a simple method to measure the thickness uniformity of the LC layer is presented. The method is based on the birefringent nature of the LC that permits the change of the polarization state of an incident linear polarized beam.…”

“…The methods presented in [19][20][21][22][23] are not suitable for use in our LCVR validation study. In [19][20][21][22], the objectives of these works are to compensate the introduced phase distortion by an LC device with low optical quality, and not the precise determination of the retardance homogeneity.…”

“…In [19][20][21][22], the objectives of these works are to compensate the introduced phase distortion by an LC device with low optical quality, and not the precise determination of the retardance homogeneity. Our aim is to develop a highly precise and accurate, quick and fully automated method for measuring, with high spatial resolution, the retardance homogeneity over the full aperture of an elevated quantity of LCVRs (90 different LCVRs).…”