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Described is a new range finder using a self-mixing laser diode (SM-LD). The range finder has a high accuracy of +or-0.15% and a wide dynamic range of 0.2-1 m using only one sensor head. Compared to ultrasonic range finders, the light beam of this laser range finder can be focused and scanned. The feasibility study shows a possible application of the range finder to a visual sensor of a robot. The proposed range finder has been successfully applied as an infrared (IR) active type range finder of a single-lens reflex camera. >

The laser scanning system with three corner cubes to measure the position and heading of a vehicle is described. The high performance and short distance (50m class) equipment for a low speed vehicle was manufactured and evaluated. The system meets expected performance, or plus minus 2 cm position accuracy and plus minus 5 arc minutes heading accuracy.

A polarization-maintaining erbium-doped fiber amplifier (PM-EDFA) for optical sensing systems has been achieved with newly developed PANDA fiber based optical components. It employs 980 nm pumping for good noise performance. A noise figure of 4.1 dB and polarization crosstalk of less than -30 dB have been achieved with a gain of 22 dB.

The authors describe a compact range-finder that uses a frequency-modulated self-mixing laser diode which measures the averaged time interval of successive external-mode hops to give a short distance from the laser diode to a resting target with rough surface. With a triangular current modulation of an optimum amplitude, the measured dynamic range is from 0.2 m to 0.5 m; the standard deviation and the repeatability are less than +or-0.25 mm and +or-1.1 mm, respectively. With a decreased amplitude, i.e. half of the optimum, the dynamic range is widened to the range of 0.2 m to 1 m; the standard deviation and the repeatability are less than +or-1.6 mm and +or-2.8 mm, respectively. This type of range-finder is suitable for application as a visual sensor of an industrial robot. >

It is proposed to use an infrared semiconductor laser rangefinder to get a just-focusing signal, for the auto-focus (AF) system of a camera. Using both a measured distance to a moving object and its speed, the lens position of a single-lens reflex (SLR) camera is controlled. The range measurement error when installed in the AF system of an SLR camera is within 1% in a range of 0.3 m to 0.6 m. The error of 1% is below the normalized depth of field of 1.5-4.0% of the camera lens, which is consistent with the fact that some clear photographs are obtained from a moving object. >

It is proposed that a novel infrared range finder be used to get a just-focusing signal for an autofocus (AF) system employing both a measured distance to a moving object and its speed, and to control the lens position of video and single-lens reflex (SLR) cameras using the AF system. Some clear photographs of a moving object have been obtained by an SLR camera using the proposed AF system. >

Measured FM responses of a semiconductor laser optically coupled off-axis to a confocal Fabry-Perot cavity are discussed. It was found that this cavity acted as a frequency discriminator and as a phase comparator for slow and fast frequency fluctuations, respectively. The crossover between them was determined by a half linewidth of the cavity. On the basis of these investigations, two kinds of coherent semiconductor laser modules were constructed. External Fabry-Perot cavities were made by using an optical fiber and a hemispherical microlens. The linewidths of these lasers were less than 25 kHz. >

New optical fiber filters are fabricated using a Mach Zehnder interferometric structure in a twin core fiber. It is possible to change the filtering characteristics by bending the twin core fiber.

We have developed a prototype fiber optic sensor that detects thickness of clear-ice and density of anti/de-ice fluids on aircraft wing. It was confirmed that our proposed sensor satisfies user's basic requirements.

This paper describes an autonomous dump trucks system being developed to overcome worker shortage problems and to prevent accidents in heavy construction sites (i.e., darn constructions , road constructions, etc.). The major distinctive functions of this system arc: (1) the autonomous driving function: this system enables unmanned dump trucks to autonomously drive at 40 km/h as planned. The difference between the planned path and the trajectory is within ±90 cm; the vehicle command system can recognize obstacles and prevent their being crashed or destroyed by, utilizing a color image processor; (2) the advanced measurement function: the laser navigation system provides measurement function (i.e., the measurement errors regarding the position and the direction are within ±50 cm and ±1 degree, respectively). This system enables two operators to manage dump trucks without drivers. It is anticipated that this system could reduce approximate 30% of the workers required at heavy construction sites in the future.

Design and manufacturing of dispersion-shifted fibers with a Gaussian profile, which is compatible to the VAD process, are studied. From the viewpoint of stable cabling, the parametric analysis is made with emphasis on the bending loss. To make the bending sensitivity of the Gaussian core fibers comparable with the conventional 1.3- μm zero-dispersion fibers, an 0.8 percent or higher index difference is required. In the experiment, the achieved loss at the 1.55-μm dispersionless wavelength is 0.21 dB/km. The effects of a ring profile around the Gaussian core on the fiber transmission characteristics also are examined. While the cutoff wavelengths are greatly lengthened by the ring, the bending sensitivity is not so affected. It is found that the index difference of the main core still dominates the bending loss of the fiber.

Various types of 1.55-μm dispersion-shifted fiber have been presented. Among them, triangular core1 and similar fibers have the advantage in terms of optical loss. Recently, a triangular profile with a ring in the cladding was proposed to minimize the bending loss.2 Our paper now describes the effect of the ring on the transmission characteristics of triangular and Gaussian core fibers.3