In this paper, we present a floating image system that consists of a stereoscopic display and a two-lens system. A 3-D image is produced inside of the stereoscopic display and that image is projected into the air by the two-lens system. From the experimental results, our proposed system successfully produces the 3-D image, without the distortion and the defects, in midair so that image is a 3-D floating image.
In this paper, the chirp volume grating recorded in photopolymer for the optical demultiplexer is presented. By using the
chirp grating, the spatial distance of fibers can be controllable. The chirp rate of the grating is investigated. As a result
of the experiment, a 51-channel 0.4-nm-spaced demultiplexer with the channel uniformity of 3.5 dB, the 3dB-bandwidth
of 0.12 nm, and the channel crosstalk of -20 dB is experimentally achieved.
Today, there are many kinds of 3D displays used to produce 3D images but these 3D images are not touchable. Therefore many researchers study how to produce a floating image from 3D image. In floating image display, a large concave mirror or a large lens is used to produce the floating image. However the lens and the concave mirror produce the defected image because magnifications of these two elements are not constant, and an image distance is not linear relationship from an object distance. In this paper we present the stereoscopic floating image system using a stereo display and two lenses. The proposed floating display system provides an impressive feel of depth, and produced image appears to be located in a free space and near the observer. The two-lens system can eliminate all defects of large convex lens because the magnifications are constant and are not related the object distance and the image distance. The experimental result shows that the proposed system successfully makes a touchable stereoscopic floating image.
Diffusion model of monomers in holographic recording media was investigated to determine diffraction efficiency and the effect of the binder structure on holographic recording in an organic-inorganic hybrid photopolymers. Experimental value and rise of diffraction efficiency for the photopolymer films containing different organic sol-gel precursor (TSPEG) were compared with theoretical plot of diffraction intensity growth against recording time based on the first Harmonic diffusion model, using various material parameters, including the monomer diffusion constant, D, polymerization rate, refractive index of monomer, binder, and polymer. The initial rate of polymerizations in the photopolymer films, evaluated by FT-IR method was compared to the polymerization rate obtained from the simulation. Diffusion time of the photopolymer determined from the simulation was a function of TSPEG content, proving that the side chain in the organic hybrid media affect the diffusion of monomer from the dark area of the photopolymer (non-local polymerization).
In this paper, the double-layer gratings recorded in photopolymer films for the optical demultiplexer is presented. The channel spacing of 0.4nm, the channel uniformity of 3.5 dB, the 3dB-bandwidth of 0.12 nm, and the channel crosstalk of -20dB is experimentally obtained.
The number of channels of an optical communication system is increasing rapidly. In this paper, the demonstration of a
130-channel demultiplexer based on the cascaded volume holographic gratings is presented. Those gratings are
recorded separately in 100-μm thickness photopolymer films, which attached on both sides of a glass substrate. They
have different grating periods, slant angles, and center wavelengths. By ultilizing this configuration, the operating
wavelength range of the optical demultiplexer could be expanded, and therefore, the number of channels of the
holographic demultiplexer is increased. As a result of the experiment, a 0.4-nm-spaced demultiplexer with the channel
uniformity of 3.5 dB, the 3dB-bandwidth of 0.12 nm, and the channel crosstalk of -20 dB is experimentally achieved.
In this paper, a fabrication of Gaussian apodized volume gratings for a holographic demultiplexer is presented. The DuPont HRF-150-38 photopolymer is used because of its stability and ease of use. Based on the Gaussian apodized grating, a 42-channel demultiplexer is optically demonstrated. The interchannel spacing, the interchannel cross-talk level and the channel uniformity of 0.4 nm, -30 dB and 1.5 dB, respectively, are obtained.
In this paper, we propose a method to fabricate the grating for a laser diode shaper. During the grating recording, a beam that has polarization mode orthogonal to those of two recording beams is added. The intensity of the additional beam is controlled by a spatial light modulator to provide the spatial variation of intensity modulation, which leads to the difference of the saturation diffraction efficiency. As the results of the experiment, the laser beam shaped by the obtained grating has Gaussian desired profile intensity and is not aberration along the propagation.
In this paper, we present a scheme of recording apodized grating using an additional laser beam polarized orthogonally to two recording beams. The additional beam has a function to control beam intensity modulation of the recording beams and, therefore, changes the saturated modulation amplitude of the grating. An investigation of the diffraction efficiency depending on the intensity modulation is implemented in DuPont’s HRF-150-38 photopolymer. As results of the experiment, holographic apodized gratings with uniform, inverse Gaussian, and triangular profiles are fabricated successfully in this material.
Fabricating holographic apodized gratings is often impeded by nonlinear property of materials, which makes the resultant profile out of expectation. In this paper, the new scheme to fabricate Gaussian apodized grating is proposed. Instead of fixed Gaussian recording beams, recording beam profiles that can compensate the nonlinear sensitivity of the material at low recording intensities are created by a gray level spatial light modulator (SLM). DuPont’s HRF-150-38 photopolymer is chosen because of its stability and ease to use. As the first result of the experiment, a Gaussian grating of 2.7±0.02mm standard deviation is recorded at 0.3mW/cm2 recording intensity after exposure of 300 seconds.
A Gaussian apodization technique applied to a transmission volume hologram for a holographic demultiplexer is proposed. A Gaussian apodized grating 15×11 mm in size, 38 µm thick, and with a 3.2-mm horizontal standard deviation of the modulating index profile is fabricated. A 22-channel demultiplexer based on that grating has been optically demonstrated. Channel spacing, interchannel crosstalk level, and channel uniformity of 0.8 nm, –30 dB, and 1.5 dB, respectively, are obtained. In addition, an insertion loss of 13 dB, which is caused by the primary limitation of this technique, is observed.
In this paper, the implementation of Gaussian apodized volume grating for a demultiplexer is presented. A 42-channel demultiplexer based on that grating is optically demonstrated. By using the Gaussian apodized grating, the crosstalk level between two channels is reduced down to -35dB. The bandwidth of a channel is 0.18 nm. The two adjacent fibers are seperated by 122.5-μm horizontal distance providing the wavelength spacing between each channel of 0.4 nm. Besides, for all 42 channels, the interchannel uniformity of 1.5 dB has been obtained.
In this paper, Gaussian apodization technique applied to a transmission volume hologram for holographic demultiplexer is proposed. The Gaussian apodized grating of 15 mm x 11 mmsize, 38 μm thickness and 3.2 mm horizontal standard deviation of the modulating index profile was fabricated. A 22-channel demultiplexer based on that grating has been optically demonstrated. The channel spacing, the interchannel cross-talk level and the channel uniformity of 0.8 nm, -30 dB and 1.5 dB, respectively, were obtained.
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