Laser system with a micro-mechanically moved mirror

• US 5,572,543 A
• Filed: 11/29/1994
• Issued: 11/05/1996
• Est. Priority Date: 04/09/1992
• Status: Expired due to Fees

• Current Assignee: Deutsche Aerospace AG (Mercedes-Benz Group AG)
• Original Assignee: Deutsche Aerospace AG (Mercedes-Benz Group AG)
• Inventors: Heinemann, Stefan, Schmitt, Nikolaus P., Kroy, Walter, Seidel, Helmut, Peuser, Peter, Mehnert, Axel
• Primary Examiner(s): Scott, Jr., Leon
• Application Number:
  US08/318,665
• Time in Patent Office: 707 Days
• Field of Search: 372/107, 372/108, 372/99, 372/98, 372/92
• US Class Current: 372/107
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 26/002 the movement or the deformation controlling the frequency of light, e.g. by Doppler effect
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 5/0833 comprising inorganic materials only
• CPC Class Codes: G02B 5/0858 the reflecting layers comprising a single metallic layer with one or more dielectric layers
• CPC Class Codes: H01S 3/025 of solid state lasers, e.g. housings or mountings
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/105 by controlling the mutual position or the reflecting properties of the reflectors of the cavity , e.g. by controlling the cavity lengthH01S3/10076, H01S3/13 take precedence
• CPC Class Codes: H01S 3/121 using intracavity mechanical devices
• CPC Class Codes: H01S 5/02326 Arrangements for relative positioning of laser diodes and optical components, e.g. grooves in the mount to fix optical fibres or lenses
• CPC Class Codes: H01S 5/14 External cavity lasers H01S5/18 takes precedence; mode locking H01S5/065
• CPC Class Codes: H01S 5/4062 with an external cavity or using internal filters, e.g. Talbot filters
• CPC Class Codes: H01S 5/42 Arrays of surface emitting lasers

Abstract

The invention provides a laser system with one or several micro-mechnically produced, actively controlled laser mirrors which are provided with an actuation device, so that the rapid manipulation of small laser mirrors is assured. The mirrors are designed so that they permit an economical production in large numbers.

Claims

1. A laser microsystem of the type having at least one mechanically actuatable laser mirror arrangement disposed in a propagation path of a laser beam, for regulating propagation of said laser beam in said path, and at least one electro-mechanical means for physically displacing said mirror arrangement, wherein said laser mirror arrangement comprises:

a carrier element; and

a mirror element comprising an optical coating, said optical coating being deposited on said carrier element;

said carrier element being supported on a semiconductor substrate by means of at least an elastic suspension member formed by etching said semicoductor, whereby said carrier element and said mirror are displacable within said propagation path of said laser beam;

wherein said carrier element is actuatably coupled to said electro-mechanical means for physical displacement of said carrier element and said mirror, to regulate said propagation of said laser beam.

2. A laser system in accordance with claim 1, wherein the mirror element comprises a free-floating mirror coating.

3. A laser system in accordance with claim 1 wherein the mirror element comprises a connection of semiconductor elements and optically coated mirror substrate elements.

4. A laser system in accordance with claim 1 wherein for modulating a laser emission frequency of said microsystems, said electromechanical means comprises means for actuating the mirror element to move longitudinally.

5. A laser system in accordance with claim 1 wherein for generating large pulses, said electromechanical means comprises means for actuating the mirror element to move in a tilting manner.

6. A laser system in accordance with claim 1 wherein said electromechanical means comprises means for actuating the mirror element to perform a complex movement.

7. A laser system according to claim 1 comprising an array containing a plurality of laser mirror arrangements and a plurality of electro-mechanical means, and further comprising:

an array of laser diodes arranged on a semiconductor material, each of said diodes having a beam deflector associated therewith on said semiconductor material;

said array of laser diodes being arranged opposite said array of mirror arrangements, whereby each of said laser diodes is coupled in communication with at least one mirror arrangement.

8. A laser system in accordance with claim 7 wherein the array containing a plurality of laser mirror arrangements is fixedly connected with the array of laser diodes, and comprises a plurality of mirror sizes and a plurality of laser systems.

9. A laser system in accordance with claim 1 wherein an array of laser diodes applied to a semiconductor material are placed opposite an array of laser mirrors, to form an array of solid body lasers pumped by laser diodes with at least one external laser mirror per laser diode.

10. A laser system in accordance with claim 1 wherein the semiconductor material supporting the laser diodes has cooling channels associated therewith for keeping the temperature of the heat-generating laser diodes constant.

19. A laser system in accordance with claim 1, wherein said electromechanical means comprises means for displacing said mirror element to perform amplitude modulation of the laser.

20. A laser system in accordance with claim 1 wherein coupled optical devices and solid body laser crystals provided with beam deflection units are placed opposite an array of laser mirrors to form an array of solid body lasers pumped by laser diodes with at least one external laser mirror per laser diode.

11. A micro-mechanical mirror for a laser system, said mirror being of the type having coatings of varied refractive indices formed in alternating sequence by means of vacuum evaporation, said mirror comprising;

a silicon or mono-crystalline substrate; and

a multi-layered coating applied to said substrate, said coating being made from a material selected from the group consisting of;

a dielectric material and a metallic material;

wherein an area of said substrate adjacent said multi-layered coating is completely removed by etching to form suspension members which displacably support the multilayered coating, whereby the multi-layer coating acts as a free-floating mirror.

12. A micro-mechanical mirror in accordance with claim 11 wherein the reflecting properties of the active mirror area are variable.

13. A micro-mechanical mirror in accordance with claim 11 wherein the optically active mirror area is a Gaussian mirror.

14. A micro-mechanical mirror in accordance with claim 11 wherein said suspension members comprise thin supporting arms made of the semiconductor substrate.

15. A micro-mechanical mirror in accordance with claim 11 wherein the semiconductor substrate is electrically connected so that the mirror constitutes an electrode which is capactively coupled with a second semiconductor substrate, and wherein a flat depression is provided which fixes the electrode distance a the movable part, and thus also freedom of movement of the optically active mirror area.

16. A micro-mechanical mirror in accordance with claim 11, wherein the two semiconductor substrates are connected with each other by a bonding selected from the group consisting of anodic bonding and direct Si--Si bonding.

17. A micro-mechanical mirror in accordance with claim 11 wherein said actuating means comprises one of electrostatic, piezo-electric and magnetic elements, and wherein adjusting elements are coupled with the mirror arrangement.

18. A micro-mechanical mirror in accordance with claim 11 further comprising pneumatic means for applying a curvature to said mirror by applying a variable pressure to at least one side thereof, thereby changing a focal length of the mirror.

21. A micro-mechanical mirror in accordance with claim 11 wherein said suspension members comprise a suitable thin film.