	US 7,580,133 B2
	Interferometric apparatus for measuring moving object and optical interferometry method for measuring moving object
Nobuaki Ueki, Saitama (Japan); and Hidenori Takahashi, Saitama (Japan)
Assigned to Fujinon Corporation, Saitama-shi (Japan)
Filed on Jun. 06, 2006, as Appl. No. 11/447,164.
Claims priority of application No. P.2005-177051 (JP), filed on Jun. 16, 2005.
Prior Publication US 2007/0002333 A1, Jan. 04, 2007
Int. Cl. G01N 21/84 (2006.01); G01B 11/02 (2006.01)

U.S. Cl. 356—511 [356/429]

14 Claims

1. A moving-object measuring interferometric apparatus for measuring a moving to-be-inspected object by optical interferometry, the to-be-inspected object moving along a conveyor path, the apparatus comprising:

a light beam output section that outputs a measuring beam;

an interference optical system that obtains interference light by projecting the measuring beam onto the to-be-inspected object as the to-be-inspected object is moving along the conveyor path at a predetermined speed, wherein light reflected from the to-be-inspected object or light having passed through the to-be-inspected object interferes with reference light;

an image pickup section that obtains image information by receiving the interference light on an image pickup surface; and

an image pickup timing control section that sets a momentary image pickup period during which the to-be-inspected object can be regarded as being substantially stationary with respect to the interferometric apparatus so as to be contained in a light reception acceptable period of the image pickup surface and controls the interference light so that the interference light enters the image pickup surface only during the momentary image pickup period;

wherein the image pickup section obtains interference-fringe image information that has phase information about the to-be-inspected object during the momentary image pickup period from the interference light received on the image pickup surface during the momentary image pickup period.