A laser includes a lasing medium having a slab geometry, a waveguide arrangement either side of the slab, mirrors forming an unstable sub-resonator acting in a plane perpendicular to the waveguide, and a concave mirror arrangement acting on light incident on it launched from the waveguide, and thereby transformed from waveguide light to free space light, to redirect and retransform a portion of said light to be re-entrant waveguide light constituting the unstable sub-resonator round-trip self-re...

A pulsed laser comprises a laser rod (6), and is pumped by diode array (3) selected such that with additional components (7, 9) only a maximum of two longitudinal modes are generated between mirror (1) and output coupler (2). By slow Q-switching Q-switch (9) hoped to get a single longitudinal mode output pulse. However if on the onset of the relaxation pulse mode beating is detected by detector (28), indicating that two longitudinal modes are present, then the optical path length of the resonato...

A continuous wave laser in which the end mirrors are automatically maintained in alignment. A four-quadrant detector is centered along the path of the emerging light beam. Misalignment of the end mirrors causes an axial shift in the direction of the light beam and produces output signals from the four-quadrant detector from which can be determined the direction and amount of shift. These signals are used to servocontrol the position of one of the mirrors so as to bring it back into alignment wit...

A laser beam having a high power and preferable quality is obtained by a laser using a laser medium having a wide active region or a large mode volume. The laser includes a laser source, first and second resonator mirrors as a laser resonator optical system, an array illuminator optical system which is placed within the resonator optical system and places, at even spacing in a plane perpendicular to an optical axis of the resonator, complex amplitude distributions including only a fundamental tr...

An improved gas laser is disclosed. The laser has a support tube to support and to maintain the alignment of the optical resonator structure. The gas lasing medium is used within the support tube to maintain the tube at a substantially constant temperature above the ambient. Furthermore, an active temperature controller is disclosed. The temperature controller maintains the gas lasing medium in the support tube at a substantially constant temperature. An active pressure controller is also disclo...

A laser (2e), particularly a CO.sub.2 gas laser, is described which has a stimulating path supported on a common carrier (74e) and sub-divided into a plurality of partial paths. The partial paths (46) extend solely radially in relation to a common center (6e) and are connected to one another optically in pairs via deflecting mirrors (10e) and optical connecting paths (12e) between the deflecting mirrors (10e) at their radially outer ends. The laser (2e) is of very compact construction, has a hig...

A laser suitable for operation in a power range above 0.5 watts comprises a compact housing block defining at least first and second recesses and formed with cooling fluid channels that debouch into the first recess. A pumping source and a laser crystal are mounted in the first recess of the laser housing and beam generating and beam guiding components are mounted in the second recess of the laser housing and define conduits that are connected to the cooling fluid channels.

A laser includes a laser medium, a light source for emitting light which pumps the laser medium, a pair of mirrors which are disposed on opposite sides of the laser medium and form a resonator, an etalon which is disposed in the resonator in order to make the oscillation mode of a laser beam a single longitudinal mode and a nonlinear optical crystal which is disposed in the resonator and converts the laser beam to a second harmonic. The effective thickness t of the etalon satisfies the condition...

A laser having two feedback elements at least one which is wavelength selective, is provided with a demountable optical connector located between the gain medium of the laser and the wavelength selective feedback element. An optical waveguide is utilized to direct optical radiation between the demountable optical connector and the wavelength selective feedback element. The demountable optical connector, for example, a mechanical fibre connector allows the wavelength selective feedback element, f...

Applicant has discovered a correlation between photography, the laser mechanism, and SERS. It appears that all three effects or phenomena of photography, laser and SERS, originate from a similar mechanism, namely the amplifying factor comes from Einstein coefficients and subsequent description of inverse population--these being the essential building blocks for the aforementioned three phenomena. Accordingly, one aspect of the invention is to utilize the principles of photography in connection w...