Optically balanced instrument for high accuracy measurement of dimensional change
AssigneeCorning Incorporated
InventorsVivek Badami, Steven Patterson
Life of this patent
Estimating the term…
Abstract
An instrument for measuring dimensional changes in materials, such as ultra-low thermal expansion materials, contains an optically balanced measuring loop. Both an object beam and a loop beam propagate around the measuring loop. The object beam encounters both opposite side surfaces of the test object and the loop beam encounters remaining components of the measuring loop in common with the object beam. The object and loop beams can be separately compared to reference beams for producing heterodyne signal beams.
Claims29
An optical instrument for measuring dimensional changes of a test object between two opposite side faces of the test object comprising
- a measuring loop having a plurality of optical components and a mounting for the test object,
- a beam routing system for routing a measuring beam from a beam source to the measuring loop and from the measuring loop to a data acquisition system;
- the optical components of the measuring loop being arranged (a) for circulating a first transverse portion of the measuring beam as an object beam that encounters both of the opposite side faces of the test object and the optical components between entering and exiting the measuring loop and (b) for circulating another transverse portion of the measuring beam as a loop beam that encounters the optical components without encountering the two opposite side faces of the test object between entering and exiting the measuring loop, and
- the data acquisition system providing for directly or indirectly comparing the object and loop beams to distinguish length variations between the two opposite side faces of the test object and path length variations of the measuring loop.
An optical instrument for measuring dimensional changes of a test object between two opposite side faces of the test object comprising
- a light source for introducing first and second beams of different primary frequencies,
- a beam routing system for routing the first and second frequency beams including routing the first frequency beam into a measuring arm,
- a measuring loop within the measuring arm having a plurality of optical components and a mounting for the test object,
- the optical components being arranged for circulating a first transverse portion of the first frequency beam through encounters with both the plurality of optical components and the two opposite side faces of the test object and for circulating a second transverse portion of the first frequency beam through encounters with the same optical components without encountering the two opposite side faces of the test object, and
- the beam routing system also providing for combining the first and second transverse portions of the first frequency beam with the second frequency beam for producing heterodyne signals that can be evaluated for distinguishing length variations between the two opposite side faces of the test object from path length variations of the remaining measuring loop.
Dependencies are inferred from the claim text.