Figure 1
From: Interference phase-contrast imaging technology without beam separation
Configuration and operational principles. (a) Cross-sectional perspective view of the CIST-GC and propagation route of light. Vertically incident light a passing though the aperture area excites guided light b or goes straight down through the stacked layers as transmitted light c. Guided light b or e propagates to right and left along the lattice vector of the gratings while emitting radiated light vertically. After the radiated light mutually interferes under the shield area as shown by the arrow d, radiated light f is created. Transmitted light c is also interfered with by the radiative light under the aperture area. The transmitted light c and the radiated light f are detected by square detectors as light quantity A and B, respectively. (b) Microscopically observed plan view of the aluminum checker-pattern. The aperture shape of the aluminum pattern becomes elliptical due to the laterally etched effect. (c) Cross-sectional SEM photograph of the CIST-GC. The six paired layers of a guiding layer (Ta2O5) and a buffer layer (SiO2) are stacked while maintaining a triangular cross-section. (d) Cross-sectional chart of refractive index distribution when combining the CIST-GC with an image sensor. Film thickness: reflective layer (Al) = 0.05 µm, under-layer (SiO2) t0 = 0.850 µm, guiding layer (Ta2O5) t1 = 0.344 µm, buffer layer (SiO2) t2 = 0.220 µm. Grating shape: pitch Λg = 0.45 µm, depth dg = 0.20 µm. Al checker pattern: pitch Λ = 11.2 µm, aperture width w = 5.6 µm. Image sensor: pixel width Λ/2 = 5.6 µm. (e–i) Time-series charts of cross-sectional light intensity distribution simulated by FDTD. The boundary condition is the PML (perfect matched layer). Light source: wavelength λ = 850 nm, pulse width = 10 µm. Time interval: 9.6 µm. The pulse light is separated to right and left in the guiding layers and is detected ultimately by the sensors beneath the aperture area and the shield area.
