Position sensing apparatus, and position sensing method

• US 20060227340A1
• Filed: 03/24/2006
• Published: 10/12/2006
• Est. Priority Date: 03/30/2005
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ouchi, Toshihiko, Shioda, Michinori
• Granted Patent: US 7,701,587 B2
• Time in Patent Office: Days
• US Class Current: 356/614
• CPC Class Codes: G01B 9/02004 using frequency scans
• CPC Class Codes: G01B 9/02007 Two or more frequencies or sources used for interferometric measurement using only beat G01B9/02003
• CPC Class Codes: G01B 9/02012 using temporal intensity variation
• CPC Class Codes: G01B 9/02022 contacting one object by grazing incidence
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver

Abstract

An apparatus for sensing the position of an object includes an irradiation portion for irradiating the object with continuous electromagnetic radiation, a detection portion for detecting electromagnetic radiation reflected by the object, and an output portion for supplying a change in an amplitude intensity or a phase of the electromagnetic radiation based on information obtained by the detection portion. The position of the object is detected based on information supplied from the output portion.

Claims

1. An apparatus for sensing the position of an object, said apparatus comprising:

an irradiation portion for irradiating the object with continuous electromagnetic radiation;

a detection portion for detecting electromagnetic radiation reflected by the object; and

an output portion for supplying a change in an amplitude intensity or a phase of the electromagnetic radiation based on information obtained by the detection portion,

wherein the position of the object is detected based on information supplied from the output portion.

2. The apparatus according to claim 1, wherein the irradiation portion generates the continuous electromagnetic radiation by applying a beam created by a mixture of two laser lights from two laser diodes to a photoconductive device for emitting electromagnetic radiation.

3. The apparatus according to claim 2, wherein the frequency of the beam created by mixture of the two laser lights is equal to a difference between frequencies of the two laser lights from the two laser diodes, and the difference is in a frequency range between 30 GHz and 30 THz.

4. The apparatus according to claim 1, further comprising a time delaying system for time-delaying the electromagnetic radiation, wherein the time delaying system includes a plurality of optical paths.

5. The apparatus according to claim 4, wherein the time delaying system includes a movable stage.

6. A method of sensing the position of an object, said method comprising the steps of:

preparing an apparatus for sensing the position of an object as recited in claim 4;

time-delaying the electromagnetic radiation by the time delaying system; and

calculating a time delay corresponding to a change in the amplitude intensity or a phase of the electromagnetic radiation so that the position of the object can be detected.

7. The method according to claim 6, wherein the time delaying system includes a movable stage, and wherein the method further comprises the steps of:

detecting the amount of movement of a movable stage of the time delaying system and the change in the amplitude intensity of the electromagnetic radiation, or the amount of movement of the movable stage of the time delaying system and the change in the phase of the electromagnetic radiation; and

storing the thus-detected information as a database.

8. The method according to claim 7, further comprising the steps of:

comparing the change in the amplitude intensity of the electromagnetic radiation detected, or the change in the phase of the electromagnetic radiation detected with the information stored as the data base; and

obtaining the amount of movement of the movable stage of the time delaying system so that the position of the object can be detected.

9. The method according to claim 6, wherein an integral value of absolute values of the amplitude intensity, or the phase of the electromagnetic radiation, is used as the change in the amplitude intensity or the phase.

10. The method according to claim 6, wherein an integral value of squares of the amplitude intensity, or the phase of the electromagnetic radiation, is used as the change in the amplitude intensity or the phase.