The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 09, 1996
Filed:
Apr. 10, 1995
Makoto Takamiya, Tokyo, JP;
Jun Ashiwa, Yokohama, JP;
Hidejiro Kadowaki, Yokohama, JP;
Yasuhiko Ishida, Tokyo, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A doppler velocimeter determines the velocity of an object moving through a beam intersection area by using a doppler frequency obtained by detecting light from the beam intersecting area. The doppler velocimeter includes: a light source; a diffraction grating for diffracting light received from the light source; first and second lens systems for transmitting diffracted light from the diffraction grating to irradiate a portion of a movable object to be examined, the first and second lens systems having the same focal length F; and a detector device for receiving light from the portion of the object irradiated with the light which has been transmitted through the first and second lens systems and for obtaining a doppler signal used for velocity determination. The interval between the first and second lens systems is twice as long as the focal length F. Spherical aberration caused by a portion of the first lens system through which the diffracted light travels is offset by spherical aberration caused by a portion of the second lens system through which the diffracted light travels. This simple construction achieves equidistant interference fringes over the beam intersection area.