Abstract: An improved method of subtracting laser amplitude fluctuations from a desired signal in a multi-line laser system and a detection system having improved noise cancellation are provided. This invention reduces the noise contribution from laser amplitude fluctuations by matching the spectral dependence of the light seen at a monitor of the laser output to the spectral dependence of a desired signal. This spectral matching results in an improved correction of the laser power in a desired signal.

Abstract: A method of noise reduction in a system where polarization mode fluctuations contribute to the noise in a signal is provided. Specifically, a corrected signal is formed by adjusting the relative and overall intensity of the orthogonal polarization components of an unpolarized laser source at a first detector positioned at a first angle with respect to the laser beam axis so that the first detector has the same sensitivity to polarization as a second detector positioned at a second angle with respect to the laser beam axis. This corrected signal is then subtracted from the signal at the second detector which detects a desired signal.

Abstract: The present invention provides beam array controllers for changing the spatial and optical characteristics of a beam array. Beam array pitch controllers are provided which are capable of selectively adjusting the spacing between adjacent beams in a beam array. Beam array pitch controllers are provided which are capable of selectively adjusting the brightness and brightness spatial distribution of a beam array. The present invention also provides optical sources for generating a beam array having a selectively adjustable pitch, brightness and brightness spatial distribution.

Abstract: An improved method of subtracting laser amplitude fluctuations from a desired signal in a multi-line laser system and a detection system having improved noise cancellation are provided. This invention reduces the noise contribution from laser amplitude fluctuations by matching the spectral dependence of the light seen at a monitor of the laser output to the spectral dependence of a desired signal. This spectral matching results in an improved correction of the laser power in a desired signal.

Abstract: A method of noise reduction in a system where polarization mode fluctuations contribute to the noise in a signal is provided. Specifically, a corrected signal is formed by adjusting the relative and overall intensity of the orthogonal polarization components of an unpolarized laser source at a first detector positioned at a first angle with respect to the laser beam axis so that the first detector has the same sensitivity to polarization as a second detector positioned at a second angle with respect to the laser beam axis. This corrected signal is then subtracted from the signal at the second detector which detects a desired signal.

Abstract: A novel dual-mirror mirror mount assembly for achieving polarization of a light beam in a gaseous laser is presented. The assembly includes a mirror mount structure open at one end and having a hollow cavity therein. A pair of mirrors are hard-sealed to the mirror mount structure. The first mirror is partially reflective and the second mirror is maximally reflective. The second mirror is arranged at a predetermined angle N with respect to the first mirror such that a light beam entering said mirror mount structure follows a beam path hitting the first mirror, reflecting off the first mirror and hitting the second mirror, and then retro-reflecting back on itself along the beam path of the entering light beam. The polarization function of a Brewster window is thus achieved without the use of an intra-cavity Brewster window.

Abstract: A high-precision etalon and novel method of construction thereof is presented. The etalon comprises a pair of plane-parallel flat mirrors spaced a first distance apart, a pair of plane-parallel spacers transversely attached to the pair of mirrors which operate to fix the first distance between the pair of mirrors, and a thin film mirror layer deposited on at least one of the pair of plane-parallel flat mirrors to form a laser cavity therein of a precise second distance apart. The method of constructing an etalon in accordance with the invention includes the steps of fabricating one or more spacers, measuring the length of the spacer(s), and deriving a dimensional deviation of the spacer length from a nominal cavity dimension specified for the etalon. A thin-film pedestal is then deposited on one, the other, or both of a first and second substrate and then coated with a reflective coating. The etalon is then assembled using the spacer(s) and first and second substrates.

Abstract: Small particle identification is disclosed. A high intensity light source provides light at a sensing region for contact with small particles at the sensing region to cause resulting light that includes scattered light and emitted light due to heating of optically absorbing particles to incandescence with the resulting light terminating if vaporization of the optically absorbing particles occurs. A laser, having a laser cavity with the sensing region within the laser cavity, preferably provides high intensity laser light in the laser cavity for contact with the small particles at the sensing region. Utilizing optical detection, predetermined particle characteristic determination is enabled, including particle size and composition of optically absorbing particles.

Abstract: Apparatus and method are disclosed for minimizing performance degradation in a laser device having a laser cavity operating in a predetermined spatial mode having predetermined light beam wavefronts within the laser cavity mode. An optically transmissive unit is placed within the laser cavity and has at least one intracavity optical surface that may be positioned at or provides one end of a laser medium that is within the laser cavity with the intracavity optical surface being coincident with the laser mode wavefronts in order to minimize power losses in the laser device due to contamination buildup at the intracavity optical surface. The optic unit may also include a second optical surface that is less exposed to contamination and has a configuration suitable for providing needed focal properties for the optic unit, and one or more of the optical surfaces may have a reflection coating thereon.

Abstract: Intracavity particle detection is disclosed using optically pumped laser media. A laser medium, positioned within a laser cavity, is end-pumped by an optical pump source to excite the laser medium to provide laser light within the laser cavity, and a detecting region, also positioned within the laser cavity and capable of having particles, or particle-containing fluid, therein, is exposed to the laser light whereby light is affected, as by being scattered, by particles in the detecting region with the scattered light being indicative of particles, such as small particles having a size of between 0.05 and 10 microns, causing the light to be scattered so that the scattered light, when collected, can be used to provide an output indicative of particles at the detecting region.

Abstract: Interacvity particle detection is disclosed using optically pumped laser media. A laser medium, positioned within a laser cavity, is end-pumped by an optical pump source to excite the laser medium to provide laser light within the laser cavity, and a detecting region, also positioned within the laser cavity and capable of having particles, or particle-containing fluid, therein, is exposed to the laser light whereby light is effected, as by being scattered, by particles in the detecting region with the scattered light being indicative of particles, such as small particles having a size of between 0.05 and 10 microns, causing the light to be scattered so that the scattered light, when collected, can be used to provide an output indicative of particles at the detecting region.