# US 8,570,529 B2 · Device for position detection

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- Number: US 8,570,529 B2
- Document ID: US8570529B2
- Status: Granted
- Kind: B2
- Application number: 12/662,159
- Filed: 2010-04-01
- Published: 2010-10-14
- Granted: 2013-10-29
- Earliest claimed: 2007-10-04
- Assignees: Attocube Systems AG
- Applicants: Khaled Karrai
- Inventors: Khaled Karrai
- Web page: https://patentgrep.com/patent/US8570529B2

## CPC

- G01B 9/02081: {simultaneous quadrature detection, e.g. by spatial phase shifting}
- G01B 9/02004: using frequency scans
- G01B 11/002: {for measuring two or more coordinates}
- G01B 11/02: for measuring length, width or thickness (G01B11/08 takes precedence)
- G01B 2290/25: Fabry-Perot in interferometer, e.g. etalon, cavity
- G01B 2290/45: Multiple detectors for detecting interferometer signals
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

## Abstract

An apparatus for position finding, including a light source to produce a wave field in a measurement section, a wave field variation device to generate a variation of a wavelength of the wave field over time, an interferometer to produce an interference pattern for the wave field which is dependent on the length of the measurement section, a detector to produce a measurement signal on the basis of the detected interference pattern, and an evaluation circuit to evaluate the measurement signal on the basis of the variation over time.

## Claims

### Claim 1

A positioner, comprising:
a first fixed-position part;
a second movable part that is configured to be displaced relative to the first fixed-position part;
a position adjusting device, acting between the first fixed-position part and the second movable part, to displace the second movable part relative to the first fixed-position part, the position adjusting device comprising a slip-stick drive and being configured to displace the second movable part relative to the first fixed-position part over a path length of at least several millimeters; and
a Fabry-Perot interferometer, wherein an interferometer head of the Fabry-Perot interferometer is mounted on the first fixed-position part and light emitted from the interferometer head is reflected back to the interferometer head from the second movable part, and wherein a finesse of the Fabry-Perot interferometer is less than 10.0, particular less than 5.0, more particular less than 1.0 or still more particular less than 0.5.

### Claim 2 (depends on 1)

The positioner of claim 1, further comprising:
an optical fiber connected to the interferometer head, wherein the Fabry-Perot interferometer has an optical resonator comprising two mirrors, one mirror being formed by an end of the optical fiber and the other mirror being associated with the second movable part.

### Claim 3

An arrangement, comprising:
a positioner, the positioner including:
a first fixed-position part;
a second movable part that is configured to be displaced relative to the first fixed-position part; and
a position adjusting device, acting between the first fixed-position part and the second movable part, the position adjusting device comprising a slip-stick drive and being configured to displace the second movable part relative to the first fixed-position part over a path length of at least several millimeters; and
a position finding device to monitor the positioning movement of the positioner, the position finding device including:
a light source to produce a wave field in a measurement section of the positioner;
a wave field variation device to generate a variation of a wavelength of the wave field over time;
a Fabry-Perot interferometer to produce an interference pattern for the wave field which is dependent on the length of the measurement section;
a detector to produce a measurement signal on the basis of the detected interference pattern; and
an evaluation circuit to evaluate the measurement signal on the basis of the variation over time.

### Claim 4 (depends on 3)

The arrangement of claim 3, further comprising a cryostat, wherein the positioner and the Fabry-Perot interferometer is contained within the cryostat, and the light source, the wave field variation device, the detector and the evaluation circuit are arranged outside the cryostat.

### Claim 5 (depends on 3)

The arrangement of claim 3, wherein the optical resolution of monitoring the positioning movement of the positioner is less than 5 nm.

### Claim 6 (depends on 3)

The arrangement of claim 3, wherein a finesse of the Fabry-Perot interferometer is less than 10.0, particular less than 5.0, more particular less than 1.0 or still more particular less than 0.5.

### Claim 7 (depends on 3)

The arrangement of claim 3, wherein the Fabry-Perot interferometer has an optical resonator comprising two mirrors, one mirror being formed by an end of an optical fiber connected to an interferometer head of the Fabry-Perot interferometer, the interferometer head being connected to the first fixed-position part, and the other mirror being associated with the second movable part.