The macroscopic transfer characteristics of Kodak 120-02 and llford He-Ne/1 plates exposed to diffused laser light at 633 nm and processed in different developers for various times are reported. Diffraction efficiency and signal-to-noise ratio of amplitude holograms recorded in these materials have been checked and compared with the results obtained from other holographic emulsions.

Sensitometric and holographic data of Kodak 120-02 and llford He-Ne 1 plates

Photographic recording of spatially modulated coherent light, such as is encountered in wavefront reconstruction or coherent optical data processing, is described in terms of the amplitude transmittance (Ta) vs exposure (E) curve of the film. It is proposed that the Ta−E curve is more appropriate for this application than the D−log E curve. The nonlinear effects of recording are analyzed in this context using a nonlinear “circuit” model. A general expression for the resulting amplitude transmittance is derived by use of a Fourier-transform technique. A specific nonlinearity, the error-function limiter, is analyzed in detail to illustrate the effects of the film nonlinearity.

Photographic Recording of Spatially Modulated Coherent Light

The total light flux diffracted by a developed holographic plate is proportional to the variance of the spatial distribution of amplitude transmittance of the plate. This light forms the real and virtual holographic images and also the flare surrounding the reference beam. The variance of amplitude transmittance does not, in general, depend upon the size or form of the object, but only upon the total amount of light received from it, as this affects the beam-balance ratio. The sensitometric characteristics of the plate are taken into account by making use of three plots, namely, amplitude transmittance vs exposure, amplitude transmittance vs log exposure, and density vs log exposure. First-order expressions are derived for the ratio of the light flux diffracted by the hologram to that received from the object in terms of measurable parameters such as beam-balance ratio, average exposure, and gradient of the sensitometric curve. In like manner, we can calculate the ratio of the radiance of the holographic image to that of the original object.

Effects of Some Photographic Characteristics on the Light Flux in a Holographic Image

The Multiple-Sine-Slit Microdensitometer (MSSM) measures transmittance modulation by scanning the sample with a sinusoidal irradiance distribution generated by laser two-beam interference. The theory of the instrument is derived both from conventional microdensitometry and from treating the sample as a complex valued grating that diffracts two impinging coherent fields. The instrument has a constant MTF of 0.5; its principle disregards any phase modulations in the sample; and its large measuring area improves signal-to-noise ratio by 1-2 orders of magnitude. These are necessary qualifications for determining the MTF of recording materials of very high resolution. With a He-Ne laser, the range of the MSSM spans from 4 c/mm to 1500 c/mm. The practical implementations of the evaluation of film MTF's with this system are described.

Sensitometric and holographic data of Kodak 120-02 and llford He-Ne 1 plates

References

Photographic Recording of Spatially Modulated Coherent Light

Effects of Some Photographic Characteristics on the Light Flux in a Holographic Image

Multiple-Sine-Slit Microdensitometer and MTF Evaluation for High Resolution Emulsions. 1: Theory and Mode of Operation.

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