Interferometric measuring device

A measuring device for measuring a thickness of an optical element, the measuring device comprising:

• a light source configured to emit a measurement beam;
• a mount to hold the optical element;
• a measurement head optically coupled to the light source or comprising the light source, the measurement head being configured to:
• align the measurement beam along or parallel to an optical axis of the optical element;
• focus the measurement beam;
• direct the measurement beam along or parallel to the optical axis of the optical element;
• and
• move the focused measurement beam along or parallel to the optical axis of the optical element;
• and
• a detector configured to detect a reflected measurement beam portion, which is a reflected portion of the measurement beam reflected at a first surface and/or reflected at a second surface of the optical element, wherein the first surface of the optical element is opposite the second surface of the optical element.

A computer program for measuring a thickness of an optical element, the computer program comprising computer readable instructions, which, when executed by a processor of a measuring device comprising a light source configured to emit a measurement beam, a mount to hold the optical element, a detector, and a measurement head optically coupled to the light source or comprising the light source causes the measurement device to carry out a plurality of steps;

• wherein the measurement head is configured to:
• align the measurement beam along or parallel to an optical axis of the optical element;
• focus the measurement beam;
• direct the measurement beam along or parallel to the optical axis of the optical element;
• move the focused measurement beam along or parallel to the optical axis of the optical element;
• and
• detect a reflected measurement beam portion, which is a reflected portion of the measurement beam reflected at a first surface and/or reflected at a second surface of the optical element, wherein the first surface of the optical element is opposite the second surface of the optical element;
• and
• wherein the plurality of steps comprises:
• aligning the measurement head along or parallel to the optical axis of the optical element;
• emitting the measurement beam from the measurement head;
• focusing the measurement beam and directing the measurement beam along or parallel to the optical axis of the optical element;
• moving the focused measurement beam along or parallel to the optical axis of the optical element;
• and
• detecting a coincidence of a focal area of the focused measurement beam with a first surface of the optical element and with a second surface of the optical element, wherein the second surface is located opposite to the first surface.