A differential polarization interferometer is provided. An interferometer performs direct measurement of phase shift of a light wave passed under an arbitrary angle through a sample composed of a transparent substrate holding a thin deposited test film, for metamaterial testing. An example apparatus has a laser source and a first polarizer, and two optically connected arms. A first arm creates orthogonally polarized components of a single output beam for a broadband non-polarizing beam splitter. A second arm has a controllable phase retarder to introduce a phase shift into one polarization component of the reflected single output beam, and a second polarizer to equalize and mix the polarization components of the reflected single output beam. This transforms the reflected single output beam into a beam resulting from interference of polarization components of the reflected single output beam. A photodetector transforms an intensity of the beam into an electric signal for output.

A wavefront analyser is modified to simply determine the differences in amplitude and tilt which can exist between the different regions of an initial wavefront (S0). To achieve this, interference between two waves only is produced from beams (F1, F2) which come from neighbouring regions on the initial wavefront. Such an analyser can be used to coherently combine laser radiation produced by different sources arranged in parallel. Another use is for the determination of the differences in height and inclination which exist between the neighbouring mirror segments of a Keck telescope.

A wavefront analyser is modified to simply determine the differences in amplitude and tilt which can exist between the different regions of an initial wavefront (S0). To achieve this, interference between two waves only is produced from beams (F1, F2) which come from neighbouring regions on the initial wavefront. Such an analyser can be used to coherently combine laser radiation produced by different sources arranged in parallel. Another use is for the determination of the differences in height and inclination which exist between the neighbouring mirror segments of a Keck telescope.

A method for analyzing the wavefront effect of an optical system includes: illuminating a measurement mask (110, 310) with illumination light, producing an interferogram in a specified plane using a diffraction grating (150) from a wavefront from the illuminated measurement mask and traveling through the optical system; and capturing the interferogram with a detector (170). Different angular distributions of the illumination light incident on the measurement mask are produced via a mirror arrangement of independently settable mirror elements. A plurality of interferograms are captured in a plurality of measurement steps, wherein these measurement steps differ respectively in angular distribution of the illumination light that is incident on the measurement mask. A matching wavefront deviation portion in the measurement results obtained respectively in the measurement steps is ascertained to determine the respective system wavefront deviations of the optical system for the pupil regions illuminated respectively in the individual measurement steps.

A method of determining a reference calibration setting for an adaptive optics system (1) comprising a detecting device (8) for detecting light from an object (5); and at least one controllable wavefront modifying device (9) arranged such that light from the object (5) passes via the wavefront modifying device (9) to the detecting device (8). The method comprises the steps of: arranging (100) a light-source between the object (5) and the wavefront modifying device (9) to provide a reference light beam to the detecting device (8) via the wavefront modifying device; for each of a plurality of orthogonal wavefront modes of the wavefront modifying device: controlling (101) the wavefront modifying device to vary a magnitude of the orthogonal wavefront mode over a predetermined number of magnitude settings; acquiring (102) a series of readings of the detecting device, each reading corresponding to one of the magnitude settings; determining (103) a quality metric value indicative of an information content of the reading for each reading in the series of readings, resulting in a series of quality metric values; and determining (106) a reference parameter set for the wavefront modifying device corresponding to an optimum quality metric value based on the series of quality metric values.

A method of determining a reference calibration setting for an adaptive optics system (1) comprising a detecting device (8) for detecting light from an object (5); and at least one controllable wavefront modifying device (9) arranged such that light from the object (5) passes via the wavefront modifying device (9) to the detecting device (8). The method comprises the steps of: arranging (100) a light-source between the object (5) and the wavefront modifying device (9) to provide a reference light beam to the detecting device (8) via the wavefront modifying device; for each of a plurality of orthogonal wavefront modes of the wavefront modifying device: controlling (101) the wavefront modifying device to vary a magnitude of the orthogonal wavefront mode over a predetermined number of magnitude settings; acquiring (102) a series of readings of the detecting device, each reading corresponding to one of the magnitude settings; determining (103) a quality metric value indicative of an information content of the reading for each reading in the series of readings, resulting in a series of quality metric values; and determining (106) a reference parameter set for the wavefront modifying device corresponding to an optimum quality metric value based on the series of quality metric values.

A light source detection device may include: a cover including a common hole, a main condensing lens connected to the cover and covering the common hole, a printed circuit board provided inside the cover, a flash arranged on the printed circuit board at a position parallel to a central axis of the common hole and configured to radiate light to an outside through the common hole, and a plurality of light receiving elements comprising light receiving circuitry arranged on the printed circuit board symmetrically about the flash.

A first reflection member, when light is incident, reflects a part of the light by a first reflection surface, reflects light transmitted through the first reflection surface by a second reflection surface, and emits reflected light components in an opposite direction. The second reflection member, when light emitted from the first reflection member is incident, reflects a part of the light by a first reflection surface, reflects light transmitted through the first reflection surface by a second reflection surface, and emits reflected light components. Interference fringes are formed on a screen by light reflected on the first reflection surface of the first reflection member and the second reflection surface of the second reflection member and light reflected on the second reflection surface of the first reflection member and the first reflection surface of the second reflection member.

A first reflection member, when light is incident, reflects a part of the light by a first reflection surface, reflects light transmitted through the first reflection surface by a second reflection surface, and emits reflected light components in an opposite direction. The second reflection member, when light emitted from the first reflection member is incident, reflects a part of the light by a first reflection surface, reflects light transmitted through the first reflection surface by a second reflection surface, and emits reflected light components. Interference fringes are formed on a screen by light reflected on the first reflection surface of the first reflection member and the second reflection surface of the second reflection member and light reflected on the second reflection surface of the first reflection member and the first reflection surface of the second reflection member.

A system and method for measuring refractive index inhomogeneity between plates of a Lightguide Optical Element (LOE) uses an innovative measuring technique based on a shearing interferometric technique conventionally used to observe interference and test the collimation of light beams. Another feature of the current implementation is an innovative method for analyzing the characteristics of the generated interferogram to characterize discrepancies between adjacent plates in an LOE.