When laser light is transmitted by or reflected by a diffuser onto an object being illuminated, the object is not evenly illuminated, but is speckled with large speckles. The invention uses a moving diffuser which reduces the sizes of the speckles when the object is visually observed, and eliminates the speckles when a photographic film or plate is located at the object position and records the laser light.

When laser light is transmitted by or is reflected by a diffuser onto an object being illuminated, the object is not evenly illuminated, but is speckled with large speckles. The invention uses a moving diffuser which reduces the sizes of the speckles when the object is visually observed, and eliminates the speckles when a photographic film or plate is located at the object position and records the laser light.

In a hologram producing apparatus wherein an object beam modulated according to picture information and a reference beam which interferes with the object beam are caused to impinge upon a photosensitive recording medium, to thereby form a hologram, the modulated object beam is divided into a plurality of smaller beams by the use of a plate provided with a two-dimensional grating or a plurality of apertures.

A method of producing coherent radiation signals which have reduced coherent noise content. The method involves modulation of the position of an apodizer or aperture disposed in the optical path of the radiation provided by the coherent radiation source. The modulation causes diffraction patterns created by the apodizer or aperture to be unstable, hence reducing the noise content of the transmitted radiation. In particular, a method of producing holographic exposures containing reduced coherent noise content is disclosed. The positions of apertures or apodizers utilized in producing the holographic exposure are modulated during the exposure process. The modulation is on the order of wavelengths of the illuminating radiation used to produce the exposure. The position modulation creates a slight fogging of the exposure due to the noise, but the desired hologram is recorded with little or no decrease in efficiency. Also, a method of producing an apodizer for use in generating the holographic exposure is disclosed. During preparation of the apodizer, it is modulated in position with respect to the illuminating radiation. The position is modulated on the order of wavelengths of the illuminating radiation. The modulation procedure reduces the noise content of the apodizer.

A scanner comprising a light source, having non-uniformities, for transmitting light through an input sample, and a cassette for holding the input sample, wherein a distance from the light source to the cassette is long enough to cause the effects of the non-uniformities to be substantially reduced.