Teruji Ose

Hologram formation with red light in methylene blue sensitized dichromated gelatin.

The spectral sensitization of hardened dichromated gelatin to red light is carried out using methylene blue as sensitizer. The sensitized dichromated gelatin plate can be stored for over 1 month in an ammonia atmosphere without loss of photosensitivity. Holograms recorded in the sensitized dichromated gelatin using a He-Ne laser have high diffraction efficiency and low noise if they are swelled at a temperature near the gelatin gel melting point during development processing. Maximum diffraction efficiency has been found to be as high as 88%. The energy required to obtain 80% diffraction efficiency is 150-400 mJ/cm(2).

Lippmann color holograms recorded in methylene-blue-sensitized dichromated gelatin

Experimental techniques are described for recording Lippmann color holograms in methylene-blue-sensitized dichromated gelatin. 458-, 488-, and 514.5-nm light from an argon laser and 633-nm light from a He-Ne laser are used to record the holograms. Data on the diffraction efficiency and wavelength selectivity are presented.

Methods of increasing the sensitivity of methylene blue sensitized dichromated gelatin

Dichromated gelatin (DCG) is one of the best holographic recording materials because of its high diffraction efficiency and low noise. A major shortcoming of this material is that it is essentially insensitive to light of wavelengths much longer than 540 nm. The spectral sensitivity of DCG can be extended to red light wavelengths by adding suitable dyes such as thiazine, methylene blue, and methylene green. The sensitivity of dye-sensitized DCG exposed at 633 nm, however, is less than one-tenth of that of DCG exposed at 488 nm. In the case of methylene blue (MB)-sensitized DCG, its sensitivity to blue-green light decreases by preparation of the sensitizing solution in the alkaline state. In this Letter we present two methods of increasing the sensitivity of the MB-sensitized DCG to both the blue and red light regions. Experimental results for diffraction efficiency are given for the holograms obtained in this way. Kodak 649F plates were used as starting gelatin layer material in our experiments. The preparation method for the MB-sensitized DCG plate is shown in Table LA. Interference patterns of two collimated laser beams were recorded in the. plate with different exposures. (A 0.5-W argon laser operating at 488-nm wavelength and a 50-mW He–Ne laser were used to record the patterns.) The irradiance of each beam was equal, and the angle between two beams was 36.9°, which corresponds to the spatial frequency of the grating 1000 cycles/mm at 633-nm light. After the plate was properly developed, the diffraction efficiency was measured for each exposure. One method of increasing the sensitivity is to develop the exposed plate after a lapse of time. Experimental results for 488-nm light are shown in Fig. 1. The development procedure

Conical holographic stereograms

Abstract Methods for making conical holographic stereograms are developed for monochromatic light and white light reconstructions, and real and virtual image reconstructions. One of the advantages of a conical holographic stereogram is the possibility to reconstruct real images with a simple parallel white light illumination.

New technique for recording a Lippmann hologram

Abstract A new Lippmann hologram technique is described in which a holographic stereogram is used as master hologram. A sharp and deep synthesized three-dimensional image can be obtained by this technique. Experimental results for this hologram and discussion of the image blur are presented.

Further Study of Polarization and Interference Colors

Colorimetric analysis of the color of light passed through a birefringent crystal placed between Nicol prisms is treated more generally than hitherto discussed, by adding an achromatic retardation. It is found that, by proper choice of the achromatic retardation, the color change with respect to the change of birefringence becomes very sensitive and we call this “hypersensitive (polarization) color.”The case when the crystal has the power of rotating the plane of polarization, which can be treated in the same way, is also shown.Then the color of thin layers of dielectrics on a metallic surface is analyzed. This can be treated as an extension of the cases of polarization color. As it is difficult to give a general solution, some special cases (so called cases of “white metal”) are given and the color of the reflected light is calculated and plotted on CIE chromaticity diagram.

Measurement of spherical aberrations using a solid-state image sensor

An improved way of using the traditional Hartmann test has been evolved to measure spherical aberrations of photographic lenses. Instead of photographic plates, a solid-state linear image sensor was successfully used to achieve improvements in accuracy and in measuring efficiency. It was found possible to locate the intersection of a ray with the image plane in a few seconds, with an error of less than 0.3 microm. Two standard lenses of known data were measured to compare the results of the experiments and the calculations. The precision of the method is briefly discussed theoretically and experimentally.

Holographic Measurement of Optical Transfer Functions

Two identical holograms are set in parallel with each other giving some amount of lateral shear. The total flux of light which is diffracted from these holograms in the direction of the first order shows the auto-correlation of the complex amplitude recorded in the holograms. As a merit of this method the sinusoidal amplitude modulation of the flux to be measured is automatically introduced by the shear with a constant speed. The method is applied to the measurement of optical transfer function of a spatial phase filter.

On the Effect of Dispersion and Multiple Reflection upon the Interference Color

Interference color of thin film was calculated taking multiple reflection within the layer and/or dispersion of the layer into account, both having not been taken into account in our previous papers. The result shows that the effect of the former changes the purity of color without altering its hue, whereas the latter changes its hue and purity.

Influence of noise on the measurement of optical transfer functions by the digital Fourier-transform method

A general formula for the expected value of the error in the measured optical transfer function due to noise has been derived from a matrix expression of the digital Fourier-transform process and introducing an error matrix. A new method of OTF measurement, using a multiple slit, is proposed and compared with the conventional single-slit and knife-edge scanning methods. The relation between the expected value of the error in the optical transfer function and that in the modulation transfer function is studied theoretically. Experiments have been carried out to verify the results of the analysis.