DE3546152A1 - Laser - Google Patents

Abstract

In the case of lasers used until now, the active medium has been located close to, between or inside the excitation medium. A geometric arrangement is now selected, in the case of which self-shadowing and imaging errors of the excitation medium are completely avoided. In this case, the active medium is constructed in such a manner that it holds the excitation medium in a hole so that there is no need for any additional components for injection of the excitation energy. As a result of this measure, extremely small dimensions of a laser are achieved, while maintaining good efficiency. <IMAGE>

Description

The invention relates to a laser.

Lasers are known, e.g. B. solid-state lasers in which the active Medium is located between, next to or within the excitation medium.

The excitation energy is electrical, thermal or optical in the active Medium coupled.

With optical coupling, aberrations and shadowing result conditions, reflection losses and heat losses.

The invention has for its object to provide a laser in which these losses are almost completely avoided.

This object is achieved according to the invention in that the excitation medium is surrounded by the active medium.

This measure ensures that

• - there is no self-shadowing of the excitation medium;
• - Due to the lack of the cylindrical mirror, no aberrations in the Energy coupling into the active medium.

The advantages achieved with the invention are in particular the extreme small dimensions for the complete laser and still a good we efficiency of the laser system.

This is particularly important with medical lasers, lasers for those Distance measurement and target marking.

The laser can operate in pulsed, Q-switched or continuous wave mode be used.

The energy is supplied by mains, battery or solar operation.

Advantageous embodiments of the invention are shown in the figures wrote.  

Fig. 1 shows in two views an embodiment of a laser according to the invention with a simple mounting option.

Fig. 2 shows two views of an embodiment of the invention, in which the excitation energy supply for the excitation medium on the radiation decoupling side takes place via the electrically conductive resonator decoupling mirror applied directly to the active medium and the laser is pulsed by means of a ring-shaped passive Q-switch. In addition, a one-sided mounting of the laser head with adjustment possibility for the excitation medium with respect to the position to the active medium is shown.

Fig. 3 shows in two views an embodiment of the invention, in which the excitation energy supply for the excitation medium on the radiation decoupling side takes place via a spark gap and a one-sided holder aligned on the reflection side attached to the laser head.

Fig. 4 shows an embodiment of the active medium of the invention in which the laser oscillates in the basic mode due to the end face shape of the active medium.

The embodiment of the invention shown in Fig. 1 has a solid-state laser as an active medium ( 1 ). The solid is designed as a circular cylinder with an axial bore. The excitation medium ( 2 ), here an inert gas arc lamp, is arranged within the axial bore. The wall of the axial bore of the active medium ( 1 ) is non-reflective. The total excitation energy, leaving the excitation medium (2), can occur without loss of reflective surfaces in the active medium (1). The outer wall ( 34 ) of the active medium ( 1 ) is provided with a mirror ( 26 ) in order to use the excitation energy that was not used when the active medium ( 1 ) was first irradiated by reflection on the mirror ( 26 ) into the active medium ( 1 ) to send back. The electrodes ( 23 and 27 ) of the excitation medium ( 2 ) are provided with conductive connections ( 29 ) via plug contacts ( 28 ). The supply energy is supplied to the excitation medium ( 2 ) via these conductive connections ( 29 ). There is a narrow gap ( 30 ) between the active medium ( 1 ) and the excitation medium ( 2 ). This gap ( 30 ) is necessary to enable a simple exchange of the excitation medium ( 2 ) in cold Laserkopfzu. In addition, this gap ( 30 ) is necessary to enable the expansion of the excitation medium ( 2 ) and that of the active medium ( 1 ).

A holder ( 31 ) is attached to the outer surface ( 34 ) of the active medium ( 1 ). A thread ( 35 ) is used for fastening at a desired location. The active medium ( 1 ) is optimally mirrored on the reflection side ( 32 ) for the laser wavelength.

On the decoupling side ( 33 ), the active medium ( 1 ) is provided with a mirror that is partially transparent to the laser wavelength. It is also possible to provide the actual reflection side ( 32 ) with a partially transparent mirroring for the laser wavelength in order to obtain a laser head with two opposite laser beams. The emitted laser beam has a ring mode or both emitted laser beams have a ring mode. In order to increase the stability of the laser output power, the active medium ( 1 ) is toroidal on the reflection side ( 32 ) with a radius r for the torus. The centers of curvature ( 45 ) of the torus are located on a circle with a diameter ( 46 ) which is calculated from the diameter ( 47 ) of the active medium ( 1 ) minus the wall thickness ( 48 ) of the active medium ( 1 ).

Fig. 2 also shows a solid-state laser according to the invention, wherein said excitation medium (2) is arranged in a bore of the active medium (1). The polished outer wall ( 3 ) of the active medium ( 1 ) is provided with a selective dielectric mirror coating ( 7 ) for the excitation wavelengths of the active medium ( 1 ). For the excitation energy which cannot be used by the active medium ( 1 ) and which occur due to the spectral distribution of the emitted light of the excitation medium ( 2 ), the selective dielectric reflection ( 7 ) on the outside of the active medium ( 1 ) is transparent. The excitation medium ( 2 ) is also provided on the outside with a selective mirroring ( 13 ), which is only transparent for the excitation wavelengths for the active medium ( 1 ). An electrically conductive partially transparent mirroring, for example made of gold or chrome as a coupling-out mirror ( 8 ), is applied to the active medium ( 1 ) on the coupling-out side of the laser beam. This type of power supply via the coupling mirror ( 8 ) has the advantage over the arrangement shown in Fig. 1 that the emerging laser beam is not disturbed. On the reflection side of the active medium ( 1 ), a passive Q-switch ( 36 ) and an optimally reflective mirroring is applied as a reflection mirror ( 37 ). The electrode ( 27 ) of the excitation medium ( 2 ) is connected via an electrically conductive connection ( 4 ) to the likewise electrically conductive, direct coupling mirror ( 8 ) applied directly to the active medium ( 1 ). The first electrically conductive connecting line ( 10 ) from the decoupling side is connected to the outside ( 3 ) of the electrically conductive ring ( 9 ) attached to the active medium ( 1 ). The second electrical connection is attached to the outward electrode ( 23 ) of the excitation medium ( 2 ) by means of a clamp connection ( 5 ). This Klemmver connection ( 5 ) has a threaded bore ( 6 ) which is used to connect the power supply line. This clamp connection ( 5 ) is, for. B. with a three-point adjustment unit ( 12 ), which fit with their adjusting screws ( 41 ) into the holes ( 42 ) in a holder ( 40 ). In order to avoid electrical flashovers, an insulating layer ( 39 ) is used as the connecting element between the clamp connection ( 5 ) and the adjustment unit ( 12 ). The three-point adjustment unit ( 12 ) also has a permanent magnet ( 38 ) which connects the holder ( 40 ) for the active medium ( 1 ) and the holder ( 5 , 6 , 12 , 38 , 39 , 41 ) for the excitation medium ( 2 ). Through this connection, the excitation medium (2) can be adjusted centrally in the active medium (1). A central adjustment is also necessary to the gap ( 11 ) for the coolant transport, for. B. air between the excitation medium ( 2 ) and active medium ( 1 ) to keep free. A threaded hole ( 43 ) in the holder ( 40 ) is used to attach the laser at the desired location.

Fig. 3 shows another embodiment of a solid laser according to the invention. The structure of the exciting and the active medium corresponds to that of FIG. 2. A partially transparent mirroring as Auskoppelspie gel ( 16 ) is applied to the active medium ( 1 ) on the decoupling side of the laser beam. On the reflection side of the active medium ( 1 ), an optimally reflective mirroring is applied as a reflection mirror ( 17 ). The excitation energy supply on the decoupling side takes place via a spark gap ( 15 ). Between the electrode ( 18 ) of the excitation medium ( 2 ) on the decoupling side and an electrically conductive tip ( 19 ), which is connected to the power supply by means of a conductive connection ( 20 ) (not shown in FIG. 3), a spark gap is formed ( 15 ) formed. The distance between the spark gap ( 15 ) is slightly larger than the cylinder wall thickness of the active medium ( 1 ). This is necessary so that the emitted laser beam is not affected. The conductive connection ( 20 ), on which the tip ( 19 ) is fastened, is guided along the active medium ( 1 ) in the direction of reflection mirror ( 17 ). The holder ( 21 ) for the active medium ( 1 ) has only a slightly larger diameter than the active medium ( 1 ) itself. The holder ( 21 ) is attached in an aligned continuation on the reflection mirror side. In the center there is a clamping device ( 22 ) for the electrode ( 23 ) on the reflection side. The excitation medium ( 2 ) is adjustable within the Klemmvor direction ( 22 ). Openings ( 24 ) are located in the holder ( 21 ) in order to be able to introduce a coolant between the active medium ( 1 ) and the excitation medium ( 2 ). A set screw ( 25 ) is attached in the center of the holder ( 21 ) on the side facing away from the reflection mirror ( 17 ). On this threaded stud (25) which is conductively connected to the electrode (23) of the excitation medium (2), the energy of the one electrode (23) is supplied to the Anregungsme diums (2). This setscrew ( 25 ) is also suitable for attaching the laser head to the desired location, the counter thread being conductively connected to the energy supply for the excitation medium ( 2 ).

Fig. 4 shows the active medium ( 1 ) of another embodiment of a solid-state laser according to the invention. The structure of the excitation medium and the energy supply can be carried out as in FIG. 1. The active medium ( 1 ) is seen on the reflection side and decoupling side with separate end cuts. The individual grinding surfaces ( 51 and 53 ) are optically mirrored on both sides except on the decoupling surface ( 52 ). The individual ground surfaces ( 51 ) are also angled so that the internal laser beam is guided with a zigzag path within the active medium ( 1 ) around the cylinder axis. A ground surface, which represents the end surface ( 53 ) on the reflection side, is ground so that it is perpendicular to the optical beam path. This end surface ( 53 ) can also be spherically shaped in order to influence the divergence of the emitted laser beam.

This measure ensures that the resonator length is increased many times over the cylinder length of the active medium ( 1 ). Thus, for example, an optical transmitter with a beam diameter of 1.5 mm and an outer diameter of the active medium ( 1 ) of 10 mm, an inner diameter of the active medium of 7 mm and a geometric length of the active medium ( 1 ) of 15 mm could be produced , which has an effective internal resonator length of 255 mm. This measure also ensures that a simple supply of energy to the excitation medium ( 2 ) is possible without influencing the laser beam. The laser beam does not emerge parallel to the cylinder axis of the active medium ( 1 ).

Claims (15)

1. Laser, characterized in that the excitation medium is surrounded by the active medium. 2. Laser according to claim 1, characterized in that the active medium is a solid. 3. Laser according to claim 2, characterized in that the solid forming the active medium the end faces has toroidal cuts. 4. Laser according to one of claims 1 to 3, characterized in that in addition to the active medium and the excitation measurement dium no additional components for the energy coupling from the Anre supply medium are provided in the active medium. 5. Laser according to one of claims 1 to 4, characterized in that the internal beam path is folded. 6. Laser according to one of claims 1 to 5, characterized in that the active medium supplied several resonators is arranged. 7. Laser according to one of claims 2 to 6, characterized in that the solid forming the active medium for the end faces and separate cuts for each fold of the resonator having. 8. Laser according to claim 7, characterized in that the surfaces of the cuts are mirrored. 9. Laser according to claim 7, characterized in that the surfaces of the cuts are anti-reflective and external mirrors are provided.   10. Laser according to one of claims 1 to 9, characterized in that the excitation energy supply for the Anre medium on the beam coupling side over that on the active medium applied conductive resonator mirror. 11. Laser according to one of claims 1 to 10, characterized in that the excitation energy supply for the excitation medium on the beam coupling side via a spark gap. 12. Laser according to one of claims 1 to 11, characterized in that between the active medium and the Reflection mirror a ring-shaped passive Q-switch is located. 13. Laser according to one of claims 1 to 12, characterized in that the active medium on the inner surface for the Excitation light is anti-reflective. 14. Laser according to one of claims 1 to 13, characterized in that the active medium on the outer surface for the emitted light not contributing to the excitation of the active medium of the excitation medium is anti-reflective. 15. Laser according to one of claims 1 to 14, characterized in that the active medium on the outer surface for the Excitation light is mirrored.