Interferometer for testing forms of surface and stress and strain
AssigneeFuji Photo Optical Co., Ltd.
InventorMasatoshi Hizuka
Life of this patent
Estimating the term…
Abstract
A .lambda./4 plate is inserted into and retracted from an optical path of polarized light, thereby making it possible to select whether a noise component due to the stress strain within a test object is to be presented in fringes or not. As an operator operates an operation mechanism for a .lambda./4 plate (4), the .lambda./4 plate (4) is inserted into the optical path when a laser beam (2) should be turned into circularly polarized light, whereas the .lambda./4 plate (4) is retracted out of the optical path when the laser beam (2) should be turned into linearly polarized light.
Claims10
A transmission interferometer for testing a transparent object in which either circularly or linearly polarized measuring light is inserted between a reference plate and a reference reflecting surface, wherein said transparent test object is inserted between said reference plate and said reference reflecting surface comprising in combination:
- a source of polarized light;
- means for forming interference fringes by optical interference of polarized light passing through said test object and returning to a reference surface of said reference plate, and of a reference light component which is a component of said polarized light reflected by said reference surface,
- a .lambda./2 plate;
- a .lambda./4 plate;
- a polarized light optical path;
- means for inserting and retracting the .lambda./4 plate into said optical path at a location between said source of polarized light and said reference surface for converting said polarized light from circular to linear polarized light or linear to circular polarized light;
- means for inserting said .lambda./2 plate into said optical path when said polarized measuring light is linearly polarized light, a direction of plane of polarization of said polarized light incident on said test object is set to a direction in which a noise component in the fringes which is caused by a birefringence within said test object is minimized;
- and
- wherein, when said polarized light is circularly polarized light the noise component in the fringes which is caused by birefringence is analyzed.
A transmission interferometer for testing a transparent object for forms of surfaces and for stress and strain comprising in combination:
- a reference plate;
- a reference reflecting surface;
- wherein said transparent object is inserted between said reference plate and said reference reflecting surface;
- a source of polarized light;
- a polarized light optical path;
- a means for inserting and retracting a .lambda./4 plate into said polarized light optical path at a location between said source of polarized light and said reference surface for converting said light from circularly to linearly polarized light or from linearly to circularly polarized light;
- a .lambda./2 plate inserted into said polarized light optical path when linearly polarized light is inserted into said transparent object, for reducing a noise component caused by birefringence components to a minimum, and wherein said .lambda./2 plate is also rotatable about its own axis;
- means for forming interference fringes by optical interference of polarized light passing through said test object and returning to said reference surface of said reference plate and of a reference light component which is a component of said polarized light reflected by said reference surface;
- wherein interference fringes produced by forms of surfaces are measured when said inserted light is linear polarized light;
- and
- wherein interference fringes produced when said inserted polarized light is circularly polarized are used to measure stress and strain.
Dependencies are inferred from the claim text.