Abstract
Interferometers are widely used in science and industry to measure small displacements, changes in refractive index, and surface irregularities. In all interferometers, including phase-contrast microscopes and DICs (differential interference contrast microscopes), light from a single source is split into two beams that travel along different optical paths. They are then recombined to produce interference. The fundamental operation of beam separation makes device configuration more complex and adds to the bulk of the equipment. In this study we propose a new method of observing phase-contrast images without beam separation by using self-interference inside a grating coupler structure disposed on the observation plane. We experimentally demonstrate that the self-interference principle can generate phase-contrast images using a simple configuration. From measurements using a multilevel phase plate, we confirm its phase-contrast depth resolution to approach one- tenth of a wavelength.
Highlights
Interferometers[1,2,3,4,5,6,7,8,9,10,11,12,13] are widely used in science and industry to measure small displacements, changes in refractive index, and surface irregularities
The light distribution immediately after transmitting the CIST-GC is observed using a microscope (Edmund, #46-403 and #58-310) in place of an image sensor and the MDs are calculated from the detected electric image
It should be noted that the light beam from the laser source reaches the CIST-GC without beam separation
Summary
Interferometers[1,2,3,4,5,6,7,8,9,10,11,12,13] are widely used in science and industry to measure small displacements, changes in refractive index, and surface irregularities. In all interferometers, including phase-contrast microscopes[14,15,16,17], DICs18–21 (differential interference contrast microscopes) and grating interferometers[22,23], light from a single source is split into two beams that travel along different optical paths. A paired layer comprising a tantalum oxide film (guiding layer, thickness t1 = 0.344 μm) and a silicon oxide film (buffer layer, thickness t2 = 0.220 μm) are formed six times on the linear gratings using a self-healing effect in an auto-cloning process. A paired layer comprising a tantalum oxide film (guiding layer, thickness t1 = 0.344 μm) and a silicon oxide film (buffer layer, thickness t2 = 0.220 μm) are formed six times on the linear gratings using a self-healing effect in an auto-cloning process24 These six paired layers are formed while maintaining a triangular cross-section. The tantalum oxide layers with gratings work as a grating coupler[25,26] for vertically incident light
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