CASCADED MIRROR ARRAY AND SCANNING SYSTEM THEREOF

• US 20200132984A1
• Filed: 10/31/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: National Tsing Hua University
• Original Assignee: National Tsing Hua University
• Inventors: TSAO, Che-Chih, CHEN, Chih-Hsiang
• Granted Patent: US 11,307,406 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence

Abstract

A Cascaded Mirror Array optical scanning system applies an array of reflectors, with each reflector (called array reflector for convenience) movable between discretized angular positions and independently switched by digitized electrical signals, to process a light beam by cascaded reflections to generate desired deflection angle of the beam. The precision of the discretized angular positions of each array reflector is maintained by a support structure, which supports the reflector while allowing it to rotate or tilt, and a set of positioning limiting structure, which limits the allowable angular position of the array reflector between a finite number of angular positions corresponding to the discretized angular positions.

Claims

1. A cascaded mirror array scanner system for scanning a light beam, the system comprising:

a plurality of reflector units, each of the reflector units comprising;

an array reflector movable between a finite number of predetermined angular positions;

a support structure supporting the array reflector while allowing the array reflector to change angular position of the array reflector; and

a position limiting structure that limits movement of the array reflector to the finite number of the predetermined angular positions;

a control and driving device electrically connected to the plurality of the reflector units for generating a digital switching signal to each of the reflector units respectively to cause change of the angular positions of corresponding ones of the array reflector;

wherein the light beam is directed to pass by and be reflected by each of the array reflector in a sequential order.

2. The system of claim 1, wherein the light beam travels on a scan plane and all the predetermined angular position changes of the array reflectors are also on the scan plane, thereby enabling the cascaded mirror array system to scan the light beam on the scan plane.

3. The system of claim 2, wherein

the finite number of the predetermined angular positions of each the array reflector is two;

values of finite rotational angle corresponding to the predetermined angular positions of different the array reflectors are arranged as a geometric progression with a common ratio of two;

thereby combinations of all possible reflections by the array reflectors can result in different scan angles as an arithmetic progression.

4. The system of claim 1, wherein the support structure comprises a simple lever mechanism.

5. The system of claim 1, wherein the support structure comprises a first uneven-leg tilting mechanism for small angular position changes, the uneven-leg tilting mechanism comprising:

a base;

a first leg having an end jointed to one end of the base;

a second leg having an end jointed to the other end of the base, the second leg and the first leg having a predetermined difference in length; and

a top member having two ends jointed to the other end of the first leg and the other end of the second leg respectively;

the array reflector being disposed on the top member, thereby tilting the legs with respect to the base member resulting in small angular position changes of the top member and the array reflector.

6. The system of claim 5, wherein the position limiting structure for the first uneven-leg tilting mechanism comprises

a second uneven-leg tilting mechanism positioned between the two legs of the first uneven-leg tilting mechanism, top member of the second uneven-leg tilting mechanism acting as a first set of two landing points for position limiting purpose;

a second set of two landing points for limiting tilting positions of the second uneven-leg tilting mechanism;

independent tilting of the first and the second uneven-leg tilting mechanisms combined with the restrictions by the two sets of landing points providing four predetermined angular positions of the top member of the first uneven-leg tilting mechanism.

7. The system of claim 5, wherein the position limiting structure for the first uneven-leg tilting mechanism comprises:

a second uneven-leg tilting mechanism comprising two base positions at the middle of it two legs respectively, the first uneven-leg tilting mechanism being disposed onto the second uneven-leg tilting mechanism using the base positions as its base;

a first set of two landing points for limiting tilting positions of the first uneven-leg tilting mechanism;

a second set of two landing points for limiting tilting positions of the second uneven-leg tilting mechanism;

independent tilting of the first and the second uneven-leg tilting mechanisms combined with the restrictions by the two sets of landing points providing four predetermined angular positions of the top member of the first uneven-leg tilting mechanism.

8. The system of claim 5, wherein

the first leg, the second leg and the top member of the uneven-leg tilting mechanism comprises a conductor loop for passing switching current for titling switching purpose;

the control and driving device includes magnets positioned closed to the two legs to provide magnetic fields with directions matching the directions of the switching current.

9. The system of claim 1, wherein the position limiting structure comprises a position calibration mechanism, the position calibration mechanism comprising a first eccentric rod calibration mechanism and a combination of a second eccentric rod calibration mechanism with an uneven-leg tilting mechanism.

10. The system of claim 1,

wherein all the finite number of the predetermined angular position changes of the array reflectors are on a first scan plane for deflecting the light beam by a scan angle on the first scan plane;

wherein the cascaded mirror array system further comprises an additional set of plurality of reflector units, each of the additional reflector units comprising an array reflector movable between a finite number of predetermined angular positions oriented to deflect the light beam off the first scan plane;

wherein the light beam is directed to pass by and be reflected by each the array reflector in the two sets of plurality of reflector units in a sequential but alternating order, thereby enabling the cascaded mirror array system to perform 2D scan.

11. A reflector steering and scanning system comprising a first uneven-leg tilting mechanism for generating small angular changes of the reflector, the uneven-leg tilting mechanism comprises a base;

a first leg having an end jointed to one end of the base;

a second leg having an end jointed to the other end of the base, the second leg and the first leg having a predetermined difference in length; and

a top member having two ends jointed to the other end of the first leg and the other end of the second leg respectively;

the reflector being disposed on the top member, thereby tilting the legs with respect to the base member resulting in small angular position changes of the top member and the reflector.

12. The system of claim 11,

wherein the first leg, the second leg and the top member of the uneven-leg tilting mechanism comprises a conductor loop for passing switching current for titling switching purpose;

and

further comprising magnets positioned closed to the two legs to provide magnetic fields with directions matching the directions of the switching current.