Devices in miniature for interferometric use and fabrication thereof

• US 7,710,574 B2
• Filed: 01/23/2008
• Issued: 05/04/2010
• Est. Priority Date: 01/23/2007
• Status: Expired due to Fees

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Lee, Woo Ho, Sin, Jeongsik
• Primary Examiner(s): Chowdhury; Tarifur
• Assistant Examiner(s): Hansen; Jonathan M
• Application Number:
  US12/009,889
• Publication Number:
  US 20080285044A1
• Time in Patent Office: 832 Days
• Field of Search: 356/450, 356/451, 356/452
• US Class Current: 356/452
• CPC Class Codes: G01J 2003/4534 Interferometer on illuminating side
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/4532 Devices of compact or symmetric construction G01J3/4531 takes precedence
• 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: Y10T 29/49945 by driven force fit

Abstract

A device in miniature and fabrication of such a device for interferometric use is described, the device including a substrate with at least one deep reactive ion etching structure on at least one surface of the substrate forming an optical bench. The optical bench preferably comprises a moving stage, an actuator, one or more connector sockets and one or more optical components.

Claims

1. A device in miniature, the device comprising:

a substrate;

an optical bench on the substrate, the optical bench comprising;

one or more actuators;

a moving stage driven by at least one of the actuators;

a first connector socket with a fixed position relative to the substrate;

a second connector socket on the moving stage;

a first optical component coupled to the first connector socket, such that the first optical component is fixed relative to the substrate; and

a second optical component coupled to the second connector socket, such that the second optical component moves with the moving stage, relative to the substrate;

wherein at least one of the actuators comprises a scanning mechanism comprising at least one elongated rib comprising;

a top surface;

at least one side wall formed at least in part by deep reactive ion etching (DRIE);

dopant in the top surface of the rib; and

dopant in the side wall of the rib in an amount sufficient to increase conductivity of the rib, relative to a rib without a doped top surface and a doped side wall.

2. The device of claim 1, wherein:

the scanning mechanism comprises an actuation bar and at least one pair of elongated ribs coupled to the actuation bar, with the ribs of the pair positioned on opposite sides of the actuation bar to form a v-shaped structure with an apex, with the actuator bar at the apex; and

the device comprises a lever mechanism coupled between the actuation bar and the moving stage, the lever mechanism configured to translate movement of the actuator bar into longer movement of the moving stage.

3. The device of claim 1, wherein the optical bench comprises:

two lever mechanisms coupled to the moving stage; and

two actuators, each coupled to one of the lever mechanisms;

wherein the two lever mechanisms and the two actuators form a symmetric structure with two sides, each side comprising one of the lever mechanisms and one of the actuators.

4. The device of claim 1, wherein the second optical component comprises a mirror mounted to the second connector socket.

5. The device of claim 1, wherein substrate comprises a silicon on insulator wafer.

6. The device of claim 1, wherein the optical bench comprises three or more different types of optical components from the group consisting of:

a light source, a light detector, a mirror, a beam splitter, a ball lens, and combinations thereof.

7. The device of claim 1, wherein the at least one of the actuators comprises one or more v-beam shaped structures, each v-beam shaped structure having at least one actuation bar in contact with at least one lever mechanism.

8. The device of claim 1, wherein the moving stage comprises a comb structure for measuring capacitance and for position sensing.

9. The device of claim 1, wherein a vertical side wall at the end of the actuator is used as a mirror surface.

10. The device of claim 1, wherein some of the optical components include flexure structures as mechanical connectors.

11. A device according to claim 1, wherein:

the moving stage comprises a scanning stage;

the optical bench comprises;

a silicon micromachined optical bench with the scanning stage and with sockets for placement of optical components; and

fixtures with optical components in the sockets;

the device is operable as a miniature Michelson interferometer; and

the optical components in the fixtures comprise a ball lens and a beam splitter.

12. The microassembled device of claim 11, wherein the device has a spectrum range determined by the applied light source and detector, the light source selected from the group consisting of ultraviolet, visible, near infrared and infrared.

13. The microassembled device of claim 11, wherein the device includes a light pipe and a mirror away used to extend a light path and increase absorption of light, wherein the mirror array comprises:

a first substantially longitudinal bank of two or more mirrors in the light pipe; and

a second substantially longitudinal bank of two or more mirrors in the light pipe, substantially opposite the first bank, with the mirrors in the first and second banks aimed so that light will bounce from a first mirror in the first bank to a first mirror in the second bank, and then from the first mirror in the second bank to a second mirror in the first bank.

14. The microassembled device of claim 11, wherein the device is operable to detect one or more gases and incorporates a gas chromatography unit that delivers separated gas.

15. A method for assembly of a device in miniature, the method comprising the steps of:

fabricating an optical bench on a silicon substrate, the optical bench comprising;

a first connector socket with a fixed position relative to the substrate;

a moving stage driven by at least one of the actuators; and

a second connector socket on the moving stage;

using deep reactive ion etching (DRIE) to fabricate one or more actuators for the optical bench, wherein at least one of the actuators comprises a scanning mechanism comprising at least one elongated rib comprising;

a top surface; and

at least one side wall formed at least in part by DRIE;

after forming the at least one side wall, doping the top surface of the rib and the side wall of the rib with sufficient dopant to increase conductivity of the rib;

force fitting a first optical component into the first connector socket, such that the first optical component is fixed relative to the substrate; and

force fitting a second optical component into the second connector socket, such that the second optical component will move with the moving stage, relative to the substrate.

16. The method of claim 15, wherein the scanning mechanism comprises a v-beam shaped structure and an actuator bar to couple the v-beam shaped structure to a lever mechanism.

17. The method of claim 15, further comprising:

bonding one or more optical components in place by gluing, soldering, or a combination thereof.

18. The method of claim 15, further comprising:

adding at least one chip fixture to the optical bench, wherein the chip fixture comprises a pattern of electrical paths and a detector chip wirebonded to at least one of the electrical paths.