We propose a narrowly-shaped setup containing two prisms symmetrically placed along a straight line. This method features (1) an easy alignment, (2) the capability of hologram multiplexing using array light sources.
In the proposed optical systemm, prisms' apex angles are limited for two waves interference because of the total reflection at prism's boundary. Therefore, we should take this obstacle into consideration to design the setup. As a simplified calculation model, we assume that the wavelength of the light source is 780 nm, the refractive index of the prism is 1.51, and the focal length of the collimating lens is 10 mm, the apex angle of the first prism is 120 degrees, and that of the second prism is 90 degrees. If the largest oblique incident angle of the first prism is 10 degrees, the distance from light sources to a recording media becomes 45mm. The validity of our optical setup is confirmed experimentally by writing some holograms.
Holographic label processor for photonic network is proposed. We observe process of time-to-space conversion for optical code consisting of 2 ps pulses at a wavelength of 1.55 μm with 100 km transmission. And as a preliminary verification, label recognition using with an angular multiplexed spectral hologram as an address bank is investigated by simulations and experiments. It is confirmed the feasibility from the results.
Faint Object Camera and Spectrograph (FOCAS) is a versatile open use optical instrument of the 8.2m Subaru Telescope for the enabling imaging and spectroscopic observations. A suite of nine grisms optimized for different resolving powers and appropriate wavelength ranges have been planned for this instrument. Five grisms among the nine were fabricated by a replication method and four additional grisms with the resolving power of 5,000 are under fabrication using the volume phase holographic (VPH) gratings. A very high dispersion Echelle grism with the resolving power over 10,000 is also developing with a VPH grating sandwiched between two high index prisms. The high dispersion VPH grisms are 110 by 106 mm in aperture size and 110 mm in maximum thickness. We employed a photosensitive resin as the recording material for a thick VPH grating. In the present paper, we report the result of evaluation of the diffraction efficiency of the replica grisms and the VPH gratings by means of the rigorous coupled-wave analysis (RCWA) method to derive the optimum design parameters. An optimized VPH grating with a size of 50 by 50 mm was experimentally fabricated by means of a two-wave interference exposure at 532nm. The measured diffraction efficiency of this VPH grating is 88% at 400nm. We performed spectroscopic observations of Leonid meteors by using an image intensified CCD video camera and an experimentally fabricated VPH grism as an objective dispersion element at Nobeyama, National Astronomical Observatory of Japan in November, 2001. Consequently, we successfully obtained numerous high-quality spectroscopic data of meteors.
A different image encoded by polarization coding generates a different polarization distributed on its Fourier plane. This fact enables to realize pattern detection with polarization. The method is reported better capability to discriminate gray-level images. It has been formerly reported that we have implemented the polarization coding and polarization spatial filter using liquid crystal spatial light modulators with phase modulation and optical rotatory power. In recent years the use of bacteriorhodopsin (BR) as a holographic recording material has been studied intensively. BR films are sensitive to polarization because the BR is the photoinduced anisotropic material. In this paper, we propose the possibility of bacteriorhodopsin films for polarization spatial filter and investigate simplification of pattern detection system with polarization information.
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