H01S 3/22

The offered invention falls into field of laser equipment, more exact to the block of radiation oscillation of multichannel solid-state and gas lasers and also laser machines.

The multichannel laser machines, consisting of several independently arranged channels of oscillation blocks, are known. The radiation from these blocks is focused in synchronism, in one point for high power output (installations “Nova” and “ Novetta”[1]).

The disadvantages of these installations are in difficulty of synchronizing of oscillation blocks, and also in bulk of their construction (the overall length of installation "Nova" reaches 137 m).

Also is known the block of radiation oscillation of the multichannel laser, comprising box-shaped housing with two edge flanges, hermetically inserted inwardly of a housing; active devices, collected in a package and arranged inside a housing along its axis, while ends of active devices are output on outer sides of flanges through holes; hermetic cavity between interior walls of a housing and exterior walls of active devices for refrigerating fluid pumping; the optical resonator, consisting of a back opaque mirror, overlapping ends of active devices on the one side of package, and forward reflective - lead-out corner on the other side of package (see oscillation block of laser MTL - 2 [2]).

This block of radiation oscillation allows substantially reducing laser dimensions. It is the most closed engineering solution to stated object, i.e. prototype.

The disadvantages of the prototype lie in poor quality of laser radiation due to its high divergence, and also in difficulty of management of pulsed conditions of operation with a high mean power.

Problems of the offered invention are the improvement of generated radiation quality, magnification of frequency of generated pulses and mean powers at maintenance of construction compactness.

The indicated problems are fulfilled because the active devices are arranged in a package on a circle, on equal distance from each other, each active device has a modulator for pulse-shaping of laser radiation. The forward reflective - lead-out unit is fulfilled as a system of rotary mirrors near output ends of active devices, which arranged at an angle 45⁰ to their axes and outputting laser radiation perpendicularly to an axis of a package; central rotary mirror, arranged at an angle 45⁰ on package axes in a point of its intersection with laser radiation and rotating around of a package axis; and also anchored on a package axis transparent mirror of the optical resonator, arranged perpendicularly to laser radiation, directed from a central rotary mirror. And, besides, there is a synchronization system for rotating of a central rotary mirror and modulators of pulses.

The availability of above-mentioned structural differences as contrasted with the prototype allows changing an energy summation principle of radiation, generated in separate channels. That is to come at the next emission of radiation from each active device from summation in space to summation in time. This takes place at that moment, when the central rotary mirror is in a standing of common multiple pass of radiation from a back opaque mirror to a transparent lead-out mirror through the given active device. In result the mean output power of radiation is incremented. This takes place at simultaneous pinch of pulse frequency proportionally to the quantity of active devices and rotation rate of central rotary mirror with maintenance of construction compactness. Besides, the opportunity of radiation oscillation in continuous mode is maintained at fixed central rotary mirror, accepting laser radiation from one of active devices.

The alternate oscillation of radiation from a simple active device allows in the greatest measure killing an origin of cross modes in laser beam, generating a beam with distribution of intensity in cross-section close to TEM₀₀, and a divergence of radiation providing at diffraction level. In result is substantially improved the quality of radiation.

The construction of the block of radiation oscillation of the multichannel laser is illustrated by the drawings, where on fig. 1 is shown side view at section A - A, on fig. 2 is shown the view on the side of laser radiation outlet. The block of radiation oscillation consists of a box-shaped housing 1 with two edge flanges 2. The active devices 3, arranged along axis of housing 1, are inserted into holes of flanges 2.

In solid lasers the active devices 3 can represent solid-state active devices, for example, rods from crystals of alumino-yttrialite garnet with neodymium or from a glass with neodymium, excited by pump lamps with mirrors or with the help of pumping by a diode matrix.

In gas-discharge lasers the active devices 3 represent glass gas-discharge tubes with working gas, as a rule mixture CO₂, N₂ and He, in which with the help of high voltage, given to electrode systems in tubes, the glow discharge is ignited.

In case of gas-discharge lasers is possible a wavequide mode of radiation transfer through glass gas-discharge tubes. In the wavequide mode the radiation as though again reflects from walls of a tube to its axis, being radiated along a tube without magnification of its cross sectional dimensions. Such mode is taken place at enough small size of tubes, when ,

where a and l - radius and length of a tube, l - wave length.

The wavequide mode is characterized by essentially smaller sensitivity to a misalignment, greater selectivity of basic cross mode of radiation and greater stability of the discharge, that allows optimally selecting parameters of active medium of gas-discharge laser.

Between walls of the housing 1 and active devices 3 there is a hermetic cavity 4 for refrigerating fluid pumping.

On the one side of active devices package 3 is arranged the back opaque mirror 5 of optical resonator, overlapping all ends of active devices.

This mirror can be single-piece or sum of the opaque mirrors, conforming to each active device 5. On the other side near ends of active devices 3, at an angle 45⁰ to these devices axis are arranged the rotary mirrors 7. And on a package axis of active devices 3 is arranged the central rotary mirror 8, inclined at an angle 45⁰ to a package axis and rotated around of this axis. In a perpendicular plane to it is arranged the transparent lead-out mirror 9 of optical resonator.

As variant the transparent lead-out mirror 9 can dispose between rotary mirrors 7 and 8, perpendicularly to axes of active devices, and can be single-piece or composite, consisting from plurality of mirrors, each of which conforms to its active device and is aligns perpendicularly to active device axes. To each active device 3 is switched on the modulator 6 for pulse - shaping of laser radiation. The modulators 6 and mechanisms of rotating of central rotary mirror 8 are integrated by a synchronization system 10. The modulators 6 can be the modulators of pumping or Q – factor of the resonator.

The offered block of radiation oscillation of multichannel lasers operates as follows (figs 1,2). The active devices 3, disposed in the housing 1 with the help of flanges 2, are switched over operating conditions, for what the high voltage is given in solid lasers on pump lamps, and in gas lasers – at electrode systems, for glow discharge excitation. Thus the excitation of working medium (crystal or working gas) can take place both in pulsed conditions and in continuous. For active devices cooling through hermetic cavity 4 is pumped a refrigerating fluid. The laser radiation is formed in turn in each active device 3 at radiation reflection from the back opaque mirror 5, from one of rotary mirrors 7 and central rotary mirrors 8, and also from transparent lead-out mirror 9. The emission of laser radiation pulse from each active device 3 is carried out with the help of pulse modulators 6, switched on with the help of synchronization system 10. This takes place at that moment, when the rotated central rotary mirror 8 makes for given active device the common optical channel between transparent lead-out mirror 9 and back opaque mirror 5.

The pumping of active devices can be carried out in continuous mode, and the oscillation - in pulsing mode, that gives in magnification of pulse energy and, therefore, to increase of mean output power. The pulse frequency is regulated with quantity of active devices 3 and velocity of rotary mirror 8.

The continuous operational mode of the oscillation block is reached at stationary central rotary mirror 8. It is fixed in a standing, when the central rotary mirror 8 forms between the transparent lead-out mirror 9 and the back opaque mirror 5 the common optical channel through one of active devices 3 and rotary mirror 7.

The development of the offered laser construction is the variant, at which a pair of rotary mirrors 7 and 8 is anchored rather one another and is rotated in synchronism with laser axis, in turn collecting pulses of radiation from all active devices.

What is claimed is:

1. A block of radiation oscillation of multichannel laser, comprising a housing with two edge flanges, hermetically inserted inwardly of a housing; active devices, collected in a package and arranged inside a housing along its axis, while ends of active devices are output on outer sides of flanges through holes; a hermetic cavity between interior walls of a housing and exterior walls of active devices for refrigerating fluid pumping; an optical resonator, including a back opaque mirror, overlapping ends of active devices on one side of a package, and a forward reflective – rotary unit, characterized in, that active devices are arranged in a package on a circle, on equal distance from each other; each active device has a modulator for pulse-shaping pumping of laser medium; a forward reflective - rotary unit is fulfilled in the form of rotary mirrors system near output ends of active devices, taken place at an angle 45⁰ to their axes and outputting laser radiation perpendicularly to an axis of a package; central rotary mirror, taken place at an angle 45⁰ on axes of a package, in a point of its intersection with a laser radiation, and rotated around of an axis of a package; and also anchored on a package axis a transparent lead-out mirror of an optical resonator, arranged perpendicularly to a laser radiation, directed from a central rotary mirror; and, besides, there is a system of rotating synchronization of a central rotary mirror and pulse modulators.
2. The block according to claim1, wherein the transparent mirror is arranged on the axis of active devices package, on the opposite side of them, concerning system of rotary mirrors.
3. The block according to claim 1, wherein the translucent lead-out mirror is arranged on the side of active devices, concerning system of rotary mirrors.
4. The block according to claim 3, wherein the translucent lead-out mirror can consist of transparent mirrors system, each mirror conforms to its active device and is aligned perpendicularly axes of this active device.
5. The block according to claims 3 and 4, wherein the back opaque mirror can consist of back opaque mirrors system, aligned perpendicularly axes of conforming active device.
6. The block according to claims 1 – 5, wherein the system of rotary mirrors consists of one rotary mirror, hardly connected with the central rotary mirror and rotated in synchronism with it, in turn collecting pulses of radiation from all active devices.
7. The block according to claims 1 – 6, wherein the active device is the solid-state active device, in particular the rod from crystals of alumino-yttrialite garnet with neodymium or from a glass with neodymium, and the pumping source is gas-filled lamp, operating in pulsed conditions.
8. The block according to claims 1 – 6, wherein as an active device is used glass gas-discharge tube, filled with mixture of gases CO₂, N₂ and He and excited by a glow discharge in this gas.
9. The block according to claim 8, wherein in each glass gas-discharge tube the radiation is expanded essentially in wavequide mode.

 

 

1. Laser Systems. // Laser Program Annual Report, 1984, Lawrence Livermore National Laboratory. - P.59.
2. The handbook " Technological lasers " In 2 volumes. / G.A.Abilsiitov, V.S.Golubev, V.G.Gontar, etc. Moscow, "Maschinostroenie", 1991, p.432, (fig. 62, p. 126) (in russian).