The article describes a new optical scheme of noncontact sensor for measuring linear displacement - linear encoder.
This sensor is an optical device in which the measurement of displacement is performed by analyzing the optical signal,
which pass through two diffraction gratings, one of which is moved relative to the other. The optical signal is obtained by
the diffraction of light in these diffraction gratings and subsequent interference of diffracted beams. Often this type of
sensors are multi-channel devices with symmetrically positioned of detectors. This scheme is proposed to use a multisection
phase mask that allows to make a small-sized sensor. Sections of this multi-section phase mask are the optical
windows and they made the final interference signals to be shifted relative to each other in phase. The number of sections
in the multi-section phase mask can be varied. Estimated sufficient number of sections is four or more.
Optical position encoder consists of movable coding grating and fixed analyzing grating. Light passing and diffracting through these two gratings creates interference signal on optical detector. Decoding of interference signal phase allows to determinate current position. Known optical position encoders use several accurate adjusted optical channels and detectors to gather several signals with different phase for higher encoder accuracy. We propose to use one optical channel with several-section analyzing diffraction grating for this purpose to simplify optical scheme and adjusting requirements. Optical scheme of position encoder based on four-section analyzing diffraction grating is developed and described in this paper.
The optical scheme of holographic printer for obtaining of holographic stereograms with an increasing field of view is proposed. Conventional holographic printers allow obtaining holographic stereograms with the field of view up to 90°. Proposed scheme allows increasing field of view up to 120°. The optical scheme is based on a diffuser and a diffraction optical element, the high-aperture diffractive lens. The experience of using the composite holographic lens and the amplitude diffractive lens based on a binary Fresnel zone plate as a high-aperture diffractive lens is described. Samples of high-aperture diffractive lens with <i>f</i>-number <i>f/</i>0.3 are obtained and investigated. Samples of holographic stereograms are obtained using samples of high-aperture diffractive lens.