Diffractive optical element for a test interferometer

US12235097B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Alexander Winkler · Aalen, DE
• Martin Scheid · Aalen, DE
• Hans-Michael Stiepan · Aalen, DE
• Jochen Hetzler · Aalen, DE
• Frank Eisert · Aalen, DE

Key dates

• Filing date: Feb 18, 2022
• Grant date: Feb 25, 2025
• Expiry date: Jan 1, 2043

Classification

• Technology area (CPC G): Physics
• CPC primary: G03H2001/0072
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A diffractive optical element (10) for a test interferometer (100) measures a shape of an optical surface (102). Diffractive shape measuring structures (16) are arranged on a used surface (14) of the element and generate a test wave (122) irradiating the surface when the element is arranged in the interferometer. At least one test field (18) several profile properties of test structures contained in the test field. The profile properties characterize a profile line of the test structures extending transversely with respect to the used surface and include a flank angle of the profile line, a profile depth and a depth of a microtrench in a bottom region of a trench-shaped profile of the test structures. The test field is arranged at one location of the used surface instead of the diffractive shape measuring structures such that the test field is surrounded by several diffractive shape measuring structures.