Profile measuring apparatus

• US 20110270562A1
• Filed: 04/26/2011
• Published: 11/03/2011
• Est. Priority Date: 04/26/2010
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Ito, Yuka, Fujisawa, Haruhiko
• Granted Patent: US 9,335,160 B2
• Time in Patent Office: Days
• US Class Current: 702/94
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: G01B 11/2518 Projection by scanning of the object
• CPC Class Codes: G01B 21/20 for measuring contours or curvatures, e.g. determining profile
• CPC Class Codes: G01B 9/02055 Reduction or prevention of errors; Testing; Calibration

Abstract

According to one embodiment, a profile measuring apparatus comprises a profile measuring unit, a position acquiring unit, a profile calculating unit, a deflection detecting unit, and a controlling unit. The profile measuring unit has a projecting unit to project a pattern onto a measured object, and an imaging unit to image the pattern. The position acquiring unit acquires a position of the pattern on the measured object. The profile calculating unit calculates a profile of the measured object, based on image information from the imaging unit and position information from the position acquiring unit. The deflection detecting unit detects deflection of the projecting unit. The controlling unit executes active correction for the profile measuring unit and/or passive correction for the profile calculating unit, based on the deflection of the projecting unit detected by the deflection detecting unit.

Claims

1. A profile measuring apparatus comprising:

a profile measuring unit which has a projecting unit to project a predetermined pattern onto a measured object, and an imaging unit to image the pattern projected by the projecting unit;

a position acquiring unit which acquires a position of the profile measuring unit;

a profile calculating unit which is connected so as to be able to communicate with the imaging unit and the position acquiring unit and which calculates a profile of the measured object, based on image information from the imaging unit and position information from the position acquiring unit;

a deflection detecting unit which detects deflection of the projecting unit; and

a controlling unit which is connected to the deflection detecting unit and which executes at least either of active correction for position control or operation control of the profile measuring unit and passive correction for calculation operation of the profile calculating unit, based on the deflection of the projecting unit detected by the deflection detecting unit.

2. The profile measuring apparatus according to claim 1, further comprising a displacing mechanism which displaces the position of the profile measuring unit in accordance with an output from the controlling unit in a state in which the profile measuring unit is held thereby, as the active correction.

3. The profile measuring apparatus according to claim 2, wherein the displacing mechanism performs correction for a position on the measured object onto which the pattern is projected by the projecting unit, in accordance with the output from the controlling unit.

4. The profile measuring apparatus according to claim 2, wherein the projecting unit has a pattern forming unit which generates the predetermined pattern to be projected onto a surface of the measured object, based on light from a light source, and

wherein the displacing mechanism displaces at least a partial element of the pattern forming unit in a direction perpendicular to a projection direction of the pattern.

5. The profile measuring apparatus according to claim 4, wherein the pattern generated based on the light from the light source by the pattern forming unit, is a pattern of a line shape, and wherein the displacing mechanism displaces at least a partial element of the pattern generating unit in a direction perpendicular to a longitudinal direction of the line.

6. The profile measuring apparatus according to any one of claim 2, wherein the controlling unit controls the displacing mechanism so as to correct a position on the measured object onto which the pattern is projected by the projecting unit, based on the deflection detected by the deflection detecting unit, as the active correction.

7. The profile measuring apparatus according to claim 3, wherein the displacing mechanism is configured so as to hold the projecting unit and the imaging unit in a state in which relative positions of the projecting unit and the imaging unit are maintained fixed, and has a correcting mechanism to perform the active correction for the profile measuring unit, and a moving mechanism unit to move the correcting mechanism relative to the measured object, and

wherein the controlling unit controls the correcting mechanism so as to correct the position on the measured object onto which the pattern is projected by the projecting unit, based on a difference between the deflection detected by the deflection detecting unit and a movement amount by the moving mechanism unit.

8. The profile measuring apparatus according to claim 1, wherein the controlling unit executes correction control for the position information of the pattern acquired based on information outputted from the position acquiring unit, according to an amount of the deflection detected by the deflection detecting unit, as the passive correction.

9. The profile measuring apparatus according to claim 8, further comprising a moving mechanism unit which moves the projecting unit and the imaging unit relative to the measured object in a state in which relative positions of the projecting unit and the imaging unit are maintained,

wherein the controlling unit executes correction control for acquired position information of an image of the pattern acquired from the position acquiring unit, based on a difference between the deflection detected by the deflection detecting unit and a movement amount by the moving mechanism unit.

10. The profile measuring apparatus according to claim 1, wherein the controlling unit determines timing of imaging by the imaging unit, based on information of the deflection detected by the deflection detecting unit, as the active correction.

11. The profile measuring apparatus according to claim 10, wherein the controlling unit controls the timing of the imaging by the imaging unit so as to make the imaging unit image the pattern when a phase of the deflection is an integral multiple of a predetermined value, based on the information of the deflection detected by the deflection detecting unit.

12. The profile measuring apparatus according to claim 11, wherein the controlling unit controls the timing of the imaging by the imaging unit so as to image the pattern at such timing that a motion of the pattern image formed on the imaging unit due to the deflection is a movement amount of not more than a pixel pitch in the imaging unit in a duration of acquisition of one frame, based on the information of the deflection detected by the deflection detecting unit.

13. The profile measuring apparatus according to claim 1, wherein the controlling unit has a determining unit which determines which one of the profile measuring unit and the profile calculating unit should be a target of the control executed based on the deflection detected by the deflection detecting unit.

14. The profile measuring apparatus according to claim 13, wherein the controlling unit has a first correcting unit to control correction operation for the profile calculating unit, based on the deflection detected by the deflection detecting unit, and a second correcting unit to control correction operation for a position on the measured object onto which the pattern is projected by the projecting unit, based on the deflection detected by the deflection detecting unit, and

wherein the determining unit selects either of the correction control by the first correcting unit and the correction control by the second correcting unit, based on a result of a determination on whether an amplitude of the deflection detected by the deflection detecting unit is larger than a predetermined amplitude.

15. The profile measuring apparatus according to claim 14, wherein when the amplitude of the deflection detected by the deflection detecting unit is larger than the predetermined amplitude and when a frequency of the deflection detected by the deflection detecting unit is larger than a predetermined frequency, the determining unit determines to perform both of correction for operation of the projecting unit or the imaging unit and correction for image information from the profile calculating unit.

16. The profile measuring apparatus according to claim 1, wherein the deflection detecting unit has at least one of an angular velocity detector to detect an angular velocity of the projecting unit or the imaging unit, and an acceleration detector to detect an acceleration of the projecting unit or the imaging unit, and detects the deflection, based on at least one of the angular velocity and the acceleration.

17. The profile measuring apparatus according to claim 14, further comprising a displacing mechanism which is configured so as to keep the projecting unit and the imaging unit in a state in which relative positions of the projecting unit and the imaging unit are maintained fixed, said displacing mechanism having a correcting mechanism to perform the active correction for the profile measuring unit, and a moving mechanism unit to move the correcting mechanism relative to the measured object,

wherein the first correcting unit corrects the position information of the pattern projected onto the measured object, based on the deflection detected by the deflection detecting unit and a velocity of relative movement by the moving mechanism unit.

18. The profile measuring apparatus according to claim 17, wherein the deflection detecting unit can detect a deflection angle as the deflection, and

wherein the second correcting unit corrects the position on the measured object onto which the pattern is projected by the projecting unit, based on the deflection angle and the velocity of the relative movement by the moving mechanism unit.

19. The profile measuring apparatus according to claim 1, wherein the imaging unit has an imaging optical system to form an image of the measured object, and the imaging optical system is configured so that a plane conjugate with an imaging plane thereof includes an irradiation direction of a beam projected from the projecting unit.