Angiomyoma of the temporal region.

A case of angiomyoma of the temporal region is presented. Judging from the number of reported cases this is an uncommon site for the tumour to occur. The clinical and histopathological features of smooth muscle tumours of the superficial tissues of the head and neck are reviewed.

The meteorological satellite: overview of 25 years of operation.

The first weather satellite was launched on 1 April 1960. In the 25 years since, weather satellites have contributed to improved weather analyses and forecasts worldwide. As a maturing component of a global observing system, the meteorological satellite promises even greater financial benefits and a higher quality of life to mankind.

Laser tuners using circular piezoelectric benders.

This paper presents the results of an experimental evaluation of a new type of piezoelectric ceramic device designed for use as a laser mirror tuner. Thin plates made from various materials were assembled into a circular bimorph configuration and tested for linearity of movement, maximum travel, and resonant frequency for varying conditions of clamping torque and mirror loading values. Most of the devices tested could accept mirror diameters up to approximately 1.3 cm and maintain a resonant frequency above 2 KHz. Typical mirror translation without measurable tilt was +/-20 microm or greater for applied voltages of less than +/-300 V.

Infrared heterodyne solar radiometry.

An infrared heterodyne radiometer has sufficient sensitivity for application to high resolution spectrometric studies of the sun and the absorption of sunlight in the atmosphere. In the 10-microm region, the resolution can typically range from less than 6.7 x 10(-3)cm(-1) to 6.7 x 10(-2) cm(-1). The minimum detectable signal can approach 10(-24) W/Hz. The infrared heterodyne radiometer (IHR) can also be used for atmospheric propagation studies at the emission frequencies of the CO(2) laser for the examination of the feasibility of space-to-ground laser communication links.

Temperature-dependent etalon effects in laser systems.

This paper deals theoretically with the variety of temperature-dependent extracavity and intracavity etalon effects that must be considered in the design of laser systems. All examples refer to carbon dioxide lasers and materials appropriate for use with carbon dioxide lasers, although the analyses and results are valid for other lasers as well. Etalon effects in extracavity flats and lenses are examined, and the temperature-dependent transmittance is calculated. It is shown that the transmission of a ten-surface optical system, assumed to be uniform in temperature with 1% antireflectance coatings on each surface, can vary 18% as the system temperature varies. Temperature-dependent variations in the performance of a carbon dioxide laser are analyzed with respect to etalon effects of the laser resonator and with respect to etalon-within-an-etalon effects due to intracavity elements, e.g., an electrooptic modulator crystal. It is shown that etalon effects can produce line hopping that cannot be prevented by tuning of the laser.