An angle sensor can have a plurality of magnetic field sensing elements configured to detect a magnetic field and generate a respective plurality of magnetic field signals. In response to these magnetic field signals, a processor generates an uncorrected angle signal that is indicative of an angle of the magnetic field. An error corrector generates an error value using one or more of the previous samples of the uncorrected angle signal, and a summation element applies the error value to a current sample of the uncorrected angle signal to generate a corrected angle signal. The error corrector can generate the error value by applying a correction factor to a previous sample of the uncorrected angle signal, or by applying a correction factor to a predicted current sample of the uncorrected angle signal.

A reference laser beam locked to a femtosecond optical frequency comb is modulated through a high frequency electro-optic phase modulator, and laser sidebands with equal intervals are generated. Beat frequency is performed on the sixth-order sideband and the frequency sweeping laser beam, a beat signal and a frequency sweeping signal source are down-mixed to generate a difference frequency signal, and the difference frequency signal is locked to a reference clock through a digital phase detector and a PID controller. The frequency sweeping laser beam is locked to reference laser beam with a dynamic offset frequency under the closed loop control, and sinusoidal frequency sweeping is simultaneously performed together with the frequency sweeping signal source. The locked laser beam is used for absolute distance measurement to obtain an interference signal, a phase is obtained according to a characteristic of the sinusoidal frequency sweeping, and a distance to be measured is obtained according to the synthetic wavelength transition theory.

An optical coherence tomography (OCT) system electrically mixes a signature signal with an OCT signal (e.g., an interferogram) output by a photodetector of the OCT system. The signature signal may be a signal output by a photodetector that detects an optical signal from a fiber Bragg grating. The signature signal may then be time delayed before combination with the OCT signal. A series of interferograms are then aligned according to the signature signal. A rescaling signal may be similarly electrically mixed with the signature and OCT signals.

The invention relates to a method for compensating a magnetic locator in the presence of a magnetic-field-disturbing material, comprising: an emitter (10) comprising at least one coil emitting an emission magnetic field; a receiver (20) comprising at least one receiving coil and a device providing a plurality of measurements Ip.sub.i of a receiving magnetic field induced by the emission field in each receiving coil; and a processing unit (25) comprising a field model allowing the calculation of a position (P) and/or an orientation (Q) of the receiver by means of calculation of a prediction H.sub.i of the measurements according to a criterion (C) calculated according to an error E.sub.i which is itself calculated in relation to the measurements Ip.sub.i. The invention is characterised in that the error E.sub.i is calculated by successive iterations from initial values prescribed by the prediction H.sub.i as being the difference between the measurements Ip.sub.i and a disturbed model Hp.sub.i, according to the equation E.sub.i=Ip.sub.iHp.sub.i, the disturbed model Hp.sub.i satisfying Hp.sub.i=H.sub.i+P.sub.i (.sub.i=arctan(.sub.i), (I) the parameter being identical for all of the measurements Ip.sub.i, the calculation being carried out in such a way as to minimise the criterion C.

An interferometer uses a phase shift mask that includes an array of pixels that are aligned with a corresponding array of pixels of a detector. Each pixel in the phase shift mask is adapted to produce one of a number of predetermined phase shifts between a test beam and a reference beam. For example, the pixels may be linear polarizers or phase delay elements having one of the number of polarizer orientations or phase delays to produce the predetermined phase shifts between the test beam and the reference beam. The pixels in the phase shift mask are arranged in the array to include each of the predetermined phase shifts in repeating pixel groups in rows that are one column wide, columns that are one row high, or blocks of multiple rows and columns.

An optical coherence tomography (OCT) system electrically mixes a signature signal with an OCT signal (e.g., an interferogram) output by a photodetector of the OCT system. The signature signal may be a signal output by a photodetector that detects an optical signal from a fiber Bragg grating. The signature signal may then be time delayed before combination with the OCT signal. A series of interferograms are then aligned according to the signature signal. A rescaling signal may be similarly electrically mixed with the signature and OCT signals.

A system and method for measuring and correcting phase errors in an OCT system.

Apparatus, methods and systems relating to fluorescence imaging, and more particularly, to reducing or eliminating light sensitive and insensitive background noise in fluorescence spectroscopy systems, as well as optical coherence tomography (OCT) systems.

A photonic integrated circuit including a beam launching waveguide, a local oscillator waveguide, a target interferometer, and a reference interferometer all integrated on a chip. The beam launching waveguide transmits target electromagnetic radiation off the chip and receives a retroreflection of the target electromagnetic radiation from a target off the chip. The target interferometer interferes the retroreflection with a local oscillator field transmitted from the local oscillator waveguide so as to form a target interference signal. The reference interferometer interferes a portion of the target electromagnetic radiation that does not leave the chip with the local oscillator field transmitted from the local oscillator waveguide to form a reference interference signal. The difference between the reference interference signal and the target interference signal is used to measure a distance to the target from the chip.

An optical proximity sensor includes a first vertical cavity surface-emitting laser configured for self-mixing interferometry to determine distance to and/or velocity of an object. The optical proximity sensor also includes a second vertical cavity surface-emitting laser configured for self-mixing interferometry to determine whether any variation in a fixed distance has occurred. The optical proximity sensor leverages output from the second vertical cavity surface-emitting laser to calibrate output from the second vertical cavity surface-emitting laser to eliminate and/or mitigate environmental effects, such as temperature changes.