Methods and apparatus for aligning an etalon with a photodiode array
AssigneeCymer, Inc.
InventorRobert J. Rafac
Life of this patent
Estimating the term…
Abstract
A method and apparatus are disclosed for measuring a characteristic, e.g. spectral bandwidth, of a light beam. The apparatus may comprise an etalon for generating an interference pattern having at least one light cone, an arrangement of detector elements, the arrangement receiving a portion of the light cone and producing a signal indicative of the characteristic; and an auxiliary detector positioned to receive a portion of the light cone and produce a signal indicative of an alignment between the etalon and the linear arrangement.
Claims20
An apparatus for measuring a characteristic of a light beam, the apparatus comprising:
- an etalon for generating an interference pattern having at least one light cone,
- an arrangement of detector elements receiving a portion of the light cone and producing a signal indicative of the characteristic;
- and
- an auxiliary detector positioned to receive a portion of the light cone and produce a signal indicative of an alignment between the etalon and the arrangement of detector elements.
A method for measuring an alignment of an etalon relative to an arrangement of detector elements, the method comprising the steps of:
- positioning an auxiliary detector at a known location;
- illuminating the etalon to generate a light cone;
- adjusting a wavelength of light illuminating the etalon to illuminate the auxiliary detector and at least two locations on the arrangement of detector elements;
- and
- using the positions of the two illuminated locations on the arrangement of detector elements and the position of the illuminated auxiliary detector to determine an alignment between the etalon and the arrangement of detector elements.
A method for testing whether an etalon remains in a pre-selected alignment relative to an arrangement of detector elements comprising the steps of:
- illuminating an auxiliary detector with a portion of a light cone generated by the etalon while the etalon and arrangement of detector elements are in the pre-selected alignment;
- determining the positions of at least two locations on the arrangement of detector elements that are illuminated simultaneously with the auxiliary detector;
- and thereafter
- testing whether the pre-selected alignment is still present by:
- illuminating the auxiliary detector with a portion of a light cone generated by the etalon;
- and
- comparing locations on the arrangement of detector elements that are illuminated simultaneously with the auxiliary detector to the locations found in the determining step.
Dependencies are inferred from the claim text.