Analysis of a ring-laser gyroscope with intracavity phase-conjugate coupling

A ring-laser gyroscope with the opposite modes coupled by an intracavity phase-conjugate interaction is examined analytically and numerically. It is shown that the coupling mitigates cross-saturation-induced mode extinction, allowing a homogeneously broadened medium to be used as the gain for a laser gyroscope. It is also shown that the coupling can induce a bias beat frequency that can potentially be used as an all-optical dither. The phase conjugation is shown to affect the lock-in threshold only indirectly. The results are compared with pertinent experiments from the literature.     

Automatic three-dimensional spectrogoniometer for determination of optical properties and surface parameters

An automatic three-dimensional spectrogoniometer is presented. The wavelength of ligth and angles of incidence and observation are variable, making it capable of performing different optical characterizations in an integrated way.     

The V-scope ultrasonic motion monitor: ergonomics applications in occupational manual materials handling and clinical exercise therapy

In this paper application is made of a three-dimensional telemetric ultrasound motion analysis technology originally designed for experimentation in the physics laboratory. When applied to human motion analysis in ergonomics, sports science and orthopaedic rehabilitation, this system offers great promise of solving problems hitherto insoluble or too costly to address.     

Technique for measuring grating frequency

Experimentally the real and imaginary parts of the Fourier spectrum are separated and used to detect the nature of the object, i.e., whether the object is an odd or even function or a combination of both. A modified Twyman-Green setup is used for this purpose. This type of splitting of the object function into even and odd parts may become useful in different fields of image processing. As an application the same technique is used for accurate measurement of the grating frequency.     

Control of the polychromatic response of an optical system through the use of annular color filters

The use of annular color filters as a tool to modify the polychromatic response of an optical system is investigated. The introduction of filters with transmission that depends on the wavelength produces a significant modification of the chromaticity response. In contrast, the position in the pupil of the annuli in which the color filters are placed modifies mainly the illuminance response. The influence of different types of annular color filter on the transverse and axial responses of the aberration-free system is studied.     

High-efficiency input coupling into optical waveguides using gratings with double-surface corrugation

Waveguide grating couplers that have surface corrugation on both boundaries of the waveguide were fabricated by the deposition of waveguide material at high-vacuum pressures onto a surface-relief grating etched into the substrate. A lateral shift between the two gratings along the direction of the common grating vector was created during the waveguide deposition when the substrate normal was tilted with respect to the direction of material deposition. A series of waveguide thicknesses having an identical angle of deposition were examined to observe the effect of the waveguide thickness, and corresponding lateral shift, on the branching ratio and input-coupling efficiency. Branching ratios of above 98% and input-coupling efficiencies near the theoretical limit for an incident Gaussian beam were obtained.     

Extreme-ultraviolet interferometry at 15.5 nm using multilayer optics

The development of multilayer mirror technology capable of operating in the range of 3-30 nm and the construction of thin membranes with excellent uniformity and strength have made it possible to design and implement a Mach-Zehnder interferometer operating at 15.5 nm. We have tested this interferometer by using a soft x-ray laser as a source, and we show its use in probing high-density plasmas.