Microscopic birefringence imaging by phase-shift interferometry using a liquid crystal phase shifter

Abstract

It is known that the phase-shift intererometry is promising measurement method for the precise optical test. Liquid crystal (LC) phase shifter is very attractive as an electrically tunable phase sifter for the key component of the test system. We adopt here a bend aligned liquid crystal cell for the fast phase shifting, and mount it on the optical system of polarization microscope. A potential application for precise 2D birefringence measurement system is investigated and as high as a few tenths of a wavelength resolution can be obtained by the simple 4-step phase shifting technique. Obtained image data show the phase profile which corresponds to retardation distribution of the prepared sample, and then it becomes possible to perform quantitative analysis of 2D birefringence distribution in planar sample. Since there is basically a setting angle dependency of the test sample, measurement phase data have information of birefringence sign (positive or negative) and we can distinguish between the direction parallel and perpendicular to the anisotropic axis. We observe tiny marine zooplankton as a weakly anisotropic actual sample, and the birefringence of the muscle can be clearly detected. It is also successfully pick up that the elongated direction of muscles show higher index value.

Introduction of liquid crystal device into THz phase imaging

“…In this study, four output light intensity distribution data according to the phase shift vales for φ=π/2, π, 3/2π and 2π are recorded, and if we consider closed polarizer arrangement, those data can be described as following equations [9]:…”

“…So it becomes easy to construct PC base drive and data analysis system for 2D interference measurement system. In our previous work, we investigated the phase-shifting interferometry by using LC phase shifter in visible region [9]. Phase shifting interferometry is known as a promising method which can show very high performance without any complicated and expensive systems.…”

Optical logic circuits using double controlled logic gate

“…Thermo-optic phase shifter can be easily fabricated on MZI switch, which has power consumption 400 mW for π phase shift and it can be reduced to 45 mW with proper technology [60,61]. Liquid crystal phase shifter is also operated with very low-driving voltage (4-5 V), low-power consumption (in mW range) and high transmission rates [62][63][64][65]. This power is higher than the theoretical minimum energy (kTln2) per bit.…”

Determination of birefringence and slow axis distribution using an interferometric measurement system with liquid crystal phase shifter

“…On the other hand, we have previously investigated a simple birefringence measurement system by introducing a compact LC phase shifter into a polarization microscope system combined with a PC for LC driving and data analysis [10]. The small size of the LC cell makes it easy to be introduced as a part of the optics in any standard microscope system, and it is also easy to drive by using standard PC interface due to the low driving voltage and low power consumption.…”