Abstract: A method and apparatus for the inspection of a substrate provides consistent detection of defects such as cracks, differentiates between different types of defects, and, does not excessively heat the substrate. An infrared radiating source produces infrared energy which illuminates the substrate in a uniform manner at an incident angle. An infrared camera collects a portion of the infrared light which is reflected from the substrate. An image is created from the collected light which includes indicia of the defect. The image is examined as the incident angle is varied for changes in the appearance of the indicia.

Abstract: A method and apparatus for the inspection of a substrate provides consistent detection of defects such as cracks, differentiates between different types of defects, and, does not excessively heat the substrate. An infrared radiating source produces infrared energy which illuminates the substrate in a uniform manner at an incident angle. An infrared camera collects a portion of the infrared light which is reflected from the substrate. An image is created from the collected light which includes indicia of the defect. The image is examined as the incident angle is varied for changes in the appearance of the indicia.

Abstract: A system for making small signal gain measurements of a chemical laser, such as an HF or DF laser. The system is adapted to measure the two dimensional (x,y) gain distribution in real time (i.e. 30 to 40 frames per second). The system includes a resonating galvanometer driven scanning mirror which is able to tilt in both the horizontal x and vertical y direction. The scanning mirror is used for scanning the gain profile of an HF/DF probe laser. The tiltable scanning mirror with appropriate optics, allows the laser beam from the probe laser to be scanned while remaining parallel to the nozzle exit plane of the laser and thus allows the two dimensional scanning of the gain distribution in real time (i.e. at rates up to 40 frames per second). As such, the system is adapted to be controlled by a personal computer with the data stored on a hard disk drive therewithin.

Abstract: A method for aligning the optical surfaces of the high extraction annular ring resonator which includes a scraper mirror with a decentered aperture. A probe beam, from an external laser, is directed into the resonator cavity through the decentered aperture in the scraper mirror. The symmetrical properties of the probe beam near and far field intensity distribution patterns are used to align the optical surfaces within the cylindrical ring resonator.

Abstract: A method and apparatus for the inspection of a substrate provides consistent detection of defects such as cracks, differentiates between different types of defects, and, does not excessively heat the substrate. An infrared radiating source produces infrared energy which illuminates the substrate in a uniform manner at an incident angle. An infrared camera collects a portion of the infrared light which is reflected from the substrate. An image is created from the collected light which includes indicia of the defect. The image is examined as the incident angle is varied for changes in the appearance of the indicia.

Abstract: A method and apparatus for inspection of a substrate and a cover glass covering the substrate provides consistent detection of defects in the substrate such as cracks and cracks in the cover glass free of visual inspection of the substrate and the cover glass. An electromagnetic radiating source produces infrared radiation which illuminates the substrate and cover glass at a predetermined azimuth angle. The azimuth angle is varied such that the substrate and cover glass are illuminated at a plurality of azimuth angles. The substrate and the cover glass reflect portions of the incident electromagnetic radiation. A radiation detector collects portions of the reflected radiation and creates a plurality of images therefrom which include indicia representative of the defect in the substrate and the crack in the cover glass.

Abstract: The invention described herein is a reverse wave suppressor mirror which is purposefully aberrated in order to decrease its sensitivity to tilt when compared to a conventional reverse wave suppressor mirror.

Abstract: An unstable resonator is disclosed that couples power out of an annular gain region in a single transverse mode through the use of spherical mirrors. A four-element cavity comprising a confocal unstable resonator with a double-sided 45.degree. output coupling mirror in conjunction with a flat feedback mirror is used. A flat, totally reflecting feedback mirror is placed on the normally plane wave output side of the confocal cavity, forming an annular mode between the feedback mirror and the coupling mirror. A plane annular wave is fed back into the resonator, which alternately converges and diverges to produce an output beam in the form of a diverging annular beam. The converging wave unstable cavity has the novel property whereby increasing geometric magnification corresponds to increasing saturation of the active medium, in contrast to a conventional edge-coupled unstable cavity.

Abstract: An internal cavity calorimeter for measuring the output power from an edge coupled unstable laser resonator with a variable rectangular mode geometry while containing the radiation inside the resonator. The 45.degree. output coupling mirror of a conventional edge coupled unstable cavity is replaced by a calorimeter assembly including an absorbing copper plate having a rectangular hole of variable width w and height h to define a rectangular mode of variable width Mw and height Mh within the geometric optics approximation where M is the magnification.