Feedback sensor for M.E.M.S. mirrors

Details Feedback sensor for M.E.M.S. mirrors Feedback sensor for M.E.M.S. mirrors

1999-11-04

2003-02-18

Gutierrez, Diego (Department: 2859)

Optical: systems and elements

Deflection using a moving element

By moving a reflective element

C359S872000, C248S476000, C033SDIG001

Reexamination Certificate

active

06522445

ABSTRACT:

The invention concerns a position sensor which detects the position of a very small mirror, and provides a feedback signal indicative of the position.
BACKGROUND OF THE INVENTION
FIG. 1
illustrates a small mirror
3
, of 500 microns diameter. Since 25.4 microns are contained in one mil, which is {fraction (1/1,000)} inch, the diameter is equivalent to (500/25.4) mils, which equals about 20 mils. As two points of reference, (1) an ordinary sheet of typing paper is about four mils in thickness, and (2) the head of a straight pin, used by tailors, is about 80 mils in diameter.
The mirror is front-surface type, bearing a gold coating (not shown).
This type of mirror is used in Micro Electro Mechanical Switches, MEMS.
FIG. 2
is a simplified schematic of part of an MEMS. Mirror
3
is shown, together with photodetectors
6
, and a laser
9
. The laser
9
projects an input signal
10
to the mirror
3
. The mirror
3
is driven to a rotational position, indicated by phantom mirror
3
P, by electric fields which are not shown, and reflects the laser signal to photodetector
6
A, which delivers the signal to an output line, not shown.
In practice, feedback is provided, as shown in
FIG. 3
, to assure that the laser signal reaches the intended photodetector. For example, a second laser
12
projects a second laser beam
15
, of different frequency, which is also reflected by mirror
3
. A positioning detector
18
is associated with each photodetector
9
. Receipt of the second laser beam
15
by the appropriate positioning detector confirms that the intended photodetector receives the laser signal.
FIGS. 2 and 3
are simplifications. Actual MEMS contain two-dimensional arrays of photodetectors, and the arrays can contain
256
, or more, photodetectors. This type of MEMS is known in the art, and is described, for example, in the publication R & D, July, 1999, page 35.
One disadvantage of this type of MEMS is that the feedback system of
FIG. 3
is complex and expensive.
SUMMARY OF THE INVENTION
In one form of the invention, strain gauges are used to support the mirror. The rotational position of the mirror changes the electrical resistance of the strain gauges, thereby producing a feedback signal indicative of mirror position.


REFERENCES:
patent: 2350073 (1944-05-01), Simmons, Jr.
patent: 2416664 (1947-02-01), Ruge
patent: 2597751 (1952-05-01), Ruge
patent: 3825343 (1974-07-01), Moore
patent: 3842509 (1974-10-01), Wyman et al.
patent: 3853000 (1974-12-01), Barnett et al.
patent: 3876301 (1975-04-01), Kosugi et al.
patent: 4344172 (1982-08-01), Busse
patent: 5207000 (1993-05-01), Chang et al.
patent: 5408253 (1995-04-01), Iddan
patent: 5535043 (1996-07-01), La Fiandra et al.
patent: 5580675 (1996-12-01), Rouhani
patent: 5990473 (1999-11-01), Dickey et al.
patent: 6108118 (2000-08-01), Minamoto
patent: 6126311 (2000-10-01), Schuh
patent: 6188504 (2001-02-01), Murakami et al.
patent: 6249402 (2001-06-01), Katayama
patent: 6275326 (2001-08-01), Bhalla et al.

Affiliated with

Also associated with

Rating

Feedback sensor for M.E.M.S. mirrors does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Feedback sensor for M.E.M.S. mirrors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Feedback sensor for M.E.M.S. mirrors will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3147846