Measurement system for determining position of the optical system focal plane and focal length and method for determining position of the optical system focal plane and focal length

摘要

The invention concerns a measurements setup for determining the position of a focal plane and an effective focal length of an optical system comprising, placed on the optical axis of the optical system (4), a light source (1), a movable detector (5) and at least two identical diffraction gratings (2, 3) placed between the light source (1) and the optical system (4). The invention also concerns a method for determining the position of a focal plane and an effective focal length of an optical system, wherein the optical system (4) is placed in the measurement system between the diffraction gratings (2, 3) and the detector (5). Then, at least one diffraction grating (2, 3) rotates around the axis of the system to obtain the non-zero angle between the ruling of diffraction gratings (2, 3), and one changes the position of the detector (5) along the optical axis of the optical system (4) to find the location of the focal plane where the spots on the detector (5) overlap.