Aspects of the disclosure provide for automated self-inspection by an OCT imaging engine or device, to identify and resolve failures or inefficiencies in the hardware and/or software of the system or device during imaging. An OCT imaging engine can include a catheter connection check system for checking the quality of a physical connection point between a catheter and other components of an OCT imaging device or system. In some examples, the OCT imaging engine includes a self-inspection engine implemented to perform routine self-inspection by using a reference reflector internal to the OCT imaging engine to generate system performance data. The OCT imaging engine can use the system performance data to periodically search for and resolve failures or inefficiencies in the system. The OCT imaging engine can perform a self-calibration process to perform k-linearization and/or correct for chromatic dispersion using mirror measurements collected from an internal reference reflector.

A system and method for demodulation of a fiber optic interferometric sensor are provided. Another aspect pertains to a system and method employing a single laser to generate multiple quadratic wavelengths to demodulate fiber optic interferometric sensors with approximately sinusoidal fringes. Yet another aspect of the present system and method uses a single frequency laser which is split into multiple paths using a fiber optic coupler, with one path including an intensity modulator and another path including an acousto-optic modulator, whereafter the paths are recombined into a fiber which leads to an interferometric sensor, and the light reflected from the sensor is then directed to a photodetector. A further aspect employs a single frequency laser which is split into multiple paths, with the light in the paths being modulated at different frequencies, whereafter the paths are recombined into a fiber which leads to an interferometric sensor.

A method includes receiving a representation of an N-mode interferometer and a representation of at least one imperfection associated with the N-mode interferometer at a processor, N being a positive integer value. The processor identifies multiple two-mode interferometers and multiple phases based on the representation of the N-mode interferometer and the representation of the at least one imperfection. The multiple two-mode interferometers and the multiple phases are configured to apply a unitary transformation to an input signal. The method also includes sending a signal to cause at least one of storage or display of a representation of the multiple two-mode interferometers and a representation of the multiple phases.

A method includes receiving a representation of an N-mode interferometer and a representation of at least one imperfection associated with the N-mode interferometer at a processor, N being a positive integer value. The processor identifies multiple two-mode interferometers and multiple phases based on the representation of the N-mode interferometer and the representation of the at least one imperfection. The multiple two-mode interferometers and the multiple phases are configured to apply a unitary transformation to an input signal. The method also includes sending a signal to cause at least one of storage or display of a representation of the multiple two-mode interferometers and a representation of the multiple phases.

An adjustable beam directing optical system for a focused laser differential interferometer (FLDI) instrument according to various aspects of the present technology may include an optical half waveplate to achieve an incident linear polarization orientation with equal components of laser intensity aligned to the vertical and horizontal axis of the optical system, and an optical prism for splitting these components of an incident laser beam into two orthogonally-polarized beams equally about an optical axis of the FLDI instrument. A series of beam realignment devices positioned downstream of the optical prism are configured to selectively direct each beam to a predetermined location.

An adjustable beam directing optical system for a focused laser differential interferometer (FLDI) instrument according to various aspects of the present technology may include an optical half waveplate to achieve an incident linear polarization orientation with equal components of laser intensity aligned to the vertical and horizontal axis of the optical system, and an optical prism for splitting these components of an incident laser beam into two orthogonally-polarized beams equally about an optical axis of the FLDI instrument. A series of beam realignment devices positioned downstream of the optical prism are configured to selectively direct each beam to a predetermined location.

A light emitting device, an optical detection system, an optical detection device and an optical detection method, the light emitting device comprising: a light source (01), and an aperture limiting unit (03) located on an emergent light path of the light source (01); the light source (01) is used to emit light; and the aperture limiting unit (03) is used to limit the aperture of light emitted by the light source (01) when a current detection area of an object to be tested (05) has a high aspect ratio structure so as to block a portion of light having a large included angle with the normal direction of the object to be tested (05).

A light emitting device, an optical detection system, an optical detection device and an optical detection method, the light emitting device comprising: a light source (01), and an aperture limiting unit (03) located on an emergent light path of the light source (01); the light source (01) is used to emit light; and the aperture limiting unit (03) is used to limit the aperture of light emitted by the light source (01) when a current detection area of an object to be tested (05) has a high aspect ratio structure so as to block a portion of light having a large included angle with the normal direction of the object to be tested (05).

A measurement apparatus for measuring a thickness of a semiconductor wafer includes: an optical system configured to perpendicularly irradiate a sample wafer and a reference wafer with light, and receive interference signals of the light reflected on front and back surfaces of the respective wafers; a signal processor configured to perform frequency analysis of the interference signals received by the optical system to obtain peak positions of a point spread function of the respective wafers; and a calculator configured to calculate a thickness “tsample” of the sample wafer based on the peak position “x” of the sample wafer and the peak position “y” of the reference wafer obtained by the signal processor, and a thickness “treference” of the reference wafer.

A measurement device, for measuring the shape of an interface to be measured of an optical element having a plurality of interfaces, the device including a measurement apparatus with at least one interferometric sensor illuminated by a low-coherence source, for directing a measurement beam towards the optical element to pass through the plurality of interfaces, and to detect an interference signal resulting from interferences between the measured measurement beam reflected by the interface and a reference beam, a positioning apparatus configured for relative positioning of a coherence area of the interferometric sensor at the level of the interface to be measured, and a digital processor for producing, based on the interference signal, an item of shape information of the interface to be measured according to a field of view.