A wavefront detector (100) and method for determining a signal wavefront (Ws) of a signal beam (Ls). A beam combiner (11) is configured to combine the signal beam (Ls) with a reference beam (Lr). An image detector (12) comprising an array of photosensitive pixels (12p) is configured to receive and measure an interference pattern (Wrs) of the combined signal and reference beams (Lr+Ls). A reference light source (14) is configured to generate the reference beam (Lr). A feedback controller (20) is configured to receive an interference signal (I.sub.B) based on measurement of at least part of the combined signal and reference beams (Lr+Ls), and control generation of the reference beam (Lr) by a feedback loop based on the interference signal (I.sub.B).

A light intensity fluctuation-insensitive projection objective wave aberration detection device and a detection method thereof, comprising a light source and illumination system, an object plane marking plate, an object plane displacement table, a tested projection objective, an image plane marking plate, a two-dimensional photosensor, an image plane displacement table and a control processing unit; the object plane marking plate and the image plane marking plate are provided with grating marks for shear interference test and marks for light intensity test, the shear interferograms and the light intensity information are simultaneously received through the two-dimensional photosensor, the light intensity fluctuation error corresponding to each phase-shifting interferogram is corrected through the light intensity information, improving the detection precision, reducing the complexity and the cost of the system, and improving the detection speed.

Differential Holography technology measures the amplitude and/or phase of, e.g., an incident linearly polarized spatially coherent quasi-monochromatic optical field by optically computing the first derivative of the field and linearly mapping it to an irradiance signal detectable by an image sensor. This information recorded on the image sensor is then recovered by a simple algorithm. In some embodiments, an input field is split into two or more beams to independently compute the horizontal and vertical derivatives (using amplitude gradient filters in orthogonal orientations) for detection on one image sensor in separate regions of interest (ROIs) or on multiple image sensors. A third unfiltered beam recorded in a third ROI directly measures amplitude variations in the input field to numerically remove its contribution as noise before recovering the original wavefront using a numerical in algorithm. When combined, the measured amplitude and phase constitute a holographic recording of the incident optical field.

An interferometer system including: an optical system arranged to split a radiation beam from a laser source into a first beam along a first optical path and a second beam along a second optical path, and recombine the first beam and the second beam to a recombined beam, a detector to receive the recombined beam and to provide a detector signal based on the received recombined beam, and a processing unit, wherein a first optical path length of the first optical path and a second optical path length of the second optical path have an optical path length difference, and wherein the processing unit is arranged to determine a mode hop of the laser source on the basis of a phase shift in the detector signal.

An interferometer system including: an optical system arranged to split a radiation beam from a laser source into a first beam along a first optical path and a second beam along a second optical path, and recombine the first beam and the second beam to a recombined beam, a detector to receive the recombined beam and to provide a detector signal based on the received recombined beam, and a processing unit, wherein a first optical path length of the first optical path and a second optical path length of the second optical path have an optical path length difference, and wherein the processing unit is arranged to determine a mode hop of the laser source on the basis of a phase shift in the detector signal.

A laser source may include a laser diode, a modulation device, and a feedback device. The modulation device may include an electric power source and may be suitable for modifying a current intensity applied to the laser diode, which may modify an emission frequency of the laser diode. The feedback device may be suitable for modifying a current intensity applied to the laser diode by the electric power source as a function of the electromagnetic radiation emitted by the laser diode.

A method for reproducing a lumen curve to a given tolerance in at least one image in optical coherence tomography (OCT). Examples of applications include imaging, evaluating and diagnosing biological objects, such as, but not limited to, cardio applications, and being obtained via one or more optical instruments, such as, but not limited to, catheters. The method may include obtaining a set of original points of the curve that correspond to measurements from an optical imaging device. Filtering the set of original points using at least one criteria to obtain a subset of original points. The method may also include determining if the subset of original points is less than a predetermined threshold and adjusting the at least one criteria to increase an amount of original points included in the subset of original points when it is determined that the subset of original points is less than the predetermined threshold.

An optical sensor module includes an interferometric sensor and a set of one or more optical elements. The interferometric sensor includes a coherent light source and at least one detector configured to generate an interferometric signal. The set of one or more optical elements is configured to simultaneously direct a first portion of light emitted by the coherent light source toward a first focus area within a first depth of focus; direct a second portion of the light emitted by the coherent light source toward a second focus area within a second depth of focus; and direct portions of the emitted light that are returned from one or more objects within the first depth of focus or the second depth of focus toward the interferometric sensor.

A method for reconstructing the wavefront of a light beam by analyzing wavefront-gradient data of said light beam, the light beam containing at least one optical vortex, considering the contribution of the optical vortices to the wavefront. The method including providing a phase-gradient map g of the wavefront of the light beam, generating a Laplacian of a vector potential based on the phase gradient map g, the resulting Laplacian of the vector potential map, called “Laplacian map”, exhibiting peaks, the location of each peak corresponding to the location of an optical vortex and the integral of the peak being proportional to a topological charge n of said optical vortex, computing a singular phase map φ.sub.s based on the topological charge n and location of each optical vortex, the singular phase φ.sub.s map being representative of the contribution of the optical vortex.

A parameter measurement device of a light deflector includes a photodetector that receives output light from the light deflector, a biaxial translation automatic stage that moves the photodetector to a plurality of positions, and a signal processing device that calculates the wavelength of the output light of a wavelength sweeping light source for each time, calculates the wavelength of the light received from the light deflector by the photodetector based on the output signal of the photodetector and a previously-calculated wavelength, and calculates the incident angle of the output light beam of the wavelength sweeping light source onto the diffraction grating and an angle formed by an L-axis and a line perpendicular to the surface of the diffraction grating by performing fitting so that the coordinates of the photodetector that are obtained for each position of the photodetector and the wavelength of the light conform to a prescribed relational expression.