The recording property of newly developed photo-polymer for Holographic data storage (HDS) was studied. We designed two types of photo-polymers; Type-A and Type-B. Type-A is developed to be suitable for the collinear system. Type-B is designed by using conventional technology. The dependence of recording property on write energy was investigated. It was found that Type-A had higher sensitivity (0.16mJ/cm2), which indicated the capability of recording by a few pulse exposure, and lower scattering property. We also investigated recording property of shift multi-plexing.
We have developed grisms, designed for astronomical observation with the 8.2m Subaru telescope on Mauna Kea, Hawaii. In order to improve both efficiency and cost, we proposed a new type of grism by sandwiching a volume phase holographic (VPH) grating between two prisms, dubbed 'VPH grism'. Photosensitive materials are required for
fabrication of VPH grating with high groove density. In this paper, we employed the liquid photopolymer with high viscosity. Using the analysis program valid for the refractive index modulation grating of the rigorous coupled wave analysis (RCWA), we were able to design and fabricate a grism prototype with good performance. From the data we
obtained, it was ascertained that the experimental VPH grism had excellent performance. We further aimed to develop a VPH grism with higher dispersion and efficiency by making use of a new photopolymer that has larger refractive index modulation than the present material.
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.
We present a new type of photopolymer system for recording reflection holograms. The photopolymer system using radical and cationic photopolymerization controlled by the wavelength of light gives us enhanced diffraction efficiencies and a balanced recording sensitivity (20 approximately 60 mJ/cm2) in the blue to red region of the spectrum. In color hologram recordings, diffraction efficiencies of around 60% are obtained when using a photopolymer film composed of different spectral-sensitive photopolymer layers.