Several position sensing techniques have recently been developed for industrial applications such as mechanical alignment and kinematic calibration of industrial robots. The present article reviews position sensing techniques using diffraction and interference effects of laser light. Among them, two kinds of the position sensing techniques are described in detail. One is a technique using the FM heterodyne interferometry of a laser diode; the absolute distance from the interferometer to a reference point can be obtained from the beat frequency of the interference. The other is a technique using a small mark fabricated by a lithographic process; the position and posture of the object can be obtained from the light diffracted by the mark.

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This paper describes the studies on ion traps and laser cooling techniques and presents typical results of ion detection and laser cooling experiments. Preliminary results are also presented of generating continuous-wave coherent VUV radiation for ion storage.

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We have demonstrated high sensitivity real-time remote detection of methane in air with a 1.7-μm single-mode diode laser operating at room temperature. The laser current was modulated at 5.35 MHz and the laser center frequency was locked to a methane absorption line at 1.6659 μm. The laser light directed to the probed area was received after one-way transmission or further reflection from a topographic target. The methane absorption was detected by lock-in detection of the 10.7 MHz component in the received optical power. The detection limit in the transmission scheme was 0.3 ppm-m for a signal averaging time of 1.3 s. In the reflection scheme, the sensitivity depended on the range and the reflectance of the target. However, the amount of methane could be measured from the ratio of the 5.35 MHz and 10.7 MHz signal intensities.

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Opto-electrostatic micro-manipulation (OEMM) of cells and fine particles has been developed by using optical pressure in combination with electrostatic force. Examples of OEMM are presented: (1) a single cell feeding device. (2) introduction of fine particles into plant protoplast and their micro-manuplations inside a cell, (3) a measuring system of non-spherical cell configulations using optical trapping and electrstatic orientation. Damage to living cells caused by laser irradiation is also reported.

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A high-peak and rectangular pulse CO₂ laser excited by a 1MHz-silent discharge has been developed. With the development of a new electrode system utilizing high dielectric constant ceramics plates, homogeneous discharge of power density up to 350W/cm³ is obtained without using any pre-ionization techniques. An output peak power of 5kW in a stable TEM. mode operation is attained. Furthermore, the peak power is doubled by applying a novel unstable resonator. It is found that the laser is available for a precise cutting of brittle materials such as ceramics or glass.

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Electric and magnetic fields of the Gaussian beam of light are analyzed on the basis of Maxwell's equations without using scalar wave approximation. Field components of the planepolarized electric (or magnetic) mode or the TE (or TM) mode are explicitly described in terms of solutions of a Helmholtz equation.
Generalized solutions of the Helmholtz equation are derived and two sets of Hermite-Gaussian functions are analyzed: one is a concise form of mode functions with complex variables of Hermite polynomials, and the other is a conventional form which is expressed with real variables. Transformation between these two sets of mode functions is given.

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