Optical components

A quality assessment process for assessing the quality of an optical component, the optical component comprising an arrangement of a first and a second component grating having a component relative orientation angle, wherein the quality is assessed in terms of a deviation of the component relative orientation angle from a desired relative orientation angle, wherein the optical component and a master component comprising a substantially matching arrangement of a first and a second master grating having the desired relative orientation angle are supported by a configurable support system with the first and second component gratings in the vicinity of the first and second master gratings, the process comprising:

• receiving sensor data, the sensor data generated from light received which has interacted with both of the first gratings and light which has interacted with both of the second gratings;
• reconfiguring the support system based on the sensor data from a current configuration to a new configuration, in which the fringe spacing of a first fringe pattern formed by the first gratings is substantially maximal;
• measuring from the sensor data the fringe spacing of a second fringe pattern formed by the second gratings in the new configuration;
• and
• outputting a quality assessment based on the measured fringe spacing which is indicative of the deviation of the component relative orientation angle from the desired relative orientation angle.

An apparatus comprising:

• one or more processors;
• and
• a computer-readable storage medium having stored thereon code for assessing the quality of an optical component, the optical component comprising an arrangement of a first and a second component grating having a component relative orientation angle, wherein the quality is assessed in terms of a deviation of the component relative orientation angle from a desired relative orientation angle, wherein the optical component and a master component comprising a substantially matching arrangement of a first and a second master grating having the desired relative orientation angle are supported by a configurable support system with the first and second component gratings in the vicinity of the first and second master gratings, the code configured when executed by the one or more processors to cause operations comprising:
• receiving sensor data, the sensor data generated from light which has interacted with both of the first gratings and light which has interacted with both of the second gratings;
• reconfiguring the support system based on the sensor data from a current configuration to a new configuration, in which the fringe spacing of a first fringe pattern formed by the first gratings is substantially maximal;
• measuring from the sensor data the fringe spacing of a second fringe pattern formed by the second gratings in the new configuration;
• and
• outputting a quality assessment based on the measured fringe spacing which is indicative of the deviation of the component relative orientation angle from the desired relative orientation angle.