The source light having a range of optical wavelengths is split into sample light and reference light. The sample light is delivered into a sample, such that the sample light is scattered by the sample, resulting in signal light that exits the sample. The signal light and the reference light are combined into an interference light pattern having optical modes having oscillation frequency components respectively corresponding to optical pathlengths extending through the sample. Different sets of the optical modes of the interference light pattern are respectively detected, and high-bandwidth analog signals representative of the optical modes of the interference light pattern are output. The high-bandwidth analog signals are parallel processed, and mid-bandwidth digital signals are output. The mid-bandwidth digital signals are processed over an i number of iterations, and a plurality of low-bandwidth digital signals are output on the ith iteration. The sample is analyzed based on the low-bandwidth digital signals.

An optical interferometric range sensor includes a light source that emits light with a changing wavelength, a light splitter that splits the light emitted from the light source into a plurality of beams to be incident on a plurality of spots, an interferometer that generates, for each of the plurality of beams of the split light incident on a corresponding spot of the plurality of spots, interference light based on measurement light and reference light, a light receiver that receives the interference light to convert the interference light to an electric signal, a processor that calculates a distance from a sensor head to a measurement target based on the electric signal, an identifier that identifies the sensor head based on a beat signal generated by the interferometer, and a light adjuster that adjusts an amount of light to be incident on the measurement target based on the sensor head.

An optical interferometric range sensor includes a light source that emits light with a changing wavelength, an interferometer that receives the light emitted from the light source and generates interference light based on measurement light emitted from a sensor head to a measurement target and reflected from the measurement target and reference light traveling on an optical path at least partially different from an optical path of the measurement light, a light receiver that receives the interference light from the interferometer to convert the interference light to an electric signal, a processor that calculates a distance from the sensor head to the measurement target based on the electric signal resulting from conversion performed by the light receiver, an identifier that identifies the sensor head based on a beat signal generated by the interferometer, and a setter that sets a measurement condition corresponding to the sensor head identified by the identifier.

A laser interferometer includes: a laser light source configured to emit laser light; an optical modulator including a vibrator driven by a drive signal and configured to superimpose a modulation signal on the laser light using the vibrator; a photodetector configured to receive the laser light including a sample signal superimposed thereon due to reflection by an object and the laser light including the modulation signal, and output a light receiving signal; a calculation unit configured to perform a calculation on the light receiving signal based on a reference signal; and a signal generation unit configured to output the drive signal and the reference signal. The calculation unit includes a preprocessing unit configured to perform preprocessing for extracting a frequency modulation component from the light receiving signal based on the reference signal, and output a preprocessing signal including the frequency modulation component, a demodulation processing unit configured to demodulate the sample signal from the preprocessing signal based on the reference signal, and a correction processing unit configured to output a correction signal based on an output signal output in response to driving of the vibrator. The signal generation unit corrects the drive signal and the reference signal based on the correction signal.

In a measurement target model representing a measurement target, this measurement sensitivity calculation device uses, as measurement sensitivity, an optical path length difference between a first optical path length indicating the length of an optical path through which light emitted from a light emitter to the measurement target travels before being received by a first light receiver spaced apart by a first distance from the light emitter and a second optical path length indicating the length of an optical path through which light emitted from the light emitter travels before being received by a second light receiver spaced apart by a second distance from the light emitter, calculates the measurement sensitivity for each depth of the measurement target, and outputs the measurement sensitivity calculated for each depth of the measurement target.

A method for characterising structures etched in a substrate, such as a wafer is disclosed. The method includes, for at least one structure, at least one interferometric measurement step, carried out with a low-coherence interferometer positioned on the top side of the substrate, for measuring with a measurement beam, at least one depth data relating to a depth of said HAR structure, wherein the method also includes a first adjusting step for adjusting a diameter, at the top surface, of the measurement beam according to at least one top-CD data relating to a width of said HAR structure. The invention further relates to a system implementing such a method.

A method for characterising structures etched in a substrate, such as a wafer is disclosed. The method includes at least one structure etched in the substrate, at least one imaging step including the following steps: capturing, with an imaging device positioned on a top side of said substrate, at least one image of a top surface of the substrate, and measuring a first data relating to the structure from at least one captured image, at least one interferometric measurement step, carried out with a low-coherence interferometer positioned on the top side, for measuring with a measurement beam positioned on the structure, at least one depth data relating to a depth of said structure; wherein the method also comprises a first adjusting step for adjusting said measurement beam according to the first data. A system implementing such a method is also disclosed.

Source light having a range of optical wavelengths is generated. The source light is split into sample light and reference light. The sample light is delivered into a sample, such that the sample light is scattered by the sample, resulting in signal light that exits the sample. The signal light and the reference light are combined into an interference light pattern having optical modes, each having a direct current (DC) component and at least one alternating current (AC) component. Different subsets of the optical modes of the interference light pattern are respectively detected, and analog signals representative of the optical modes of the interference light pattern are output. Pair of the analog signals are subtracted from each other, and differential analog signals are output. The sample is analyzed based on the differential analog signals.

A signal control module integrated to a low coherence interferometry including a one-dimensional (1D) array image sensor is provided. The signal control module includes an image acquisition controller and a signal controller. The image acquisition controller sends a 1D image acquisition control signal. The signal controller sends a two-dimensional (2D) image acquisition control signal, wherein the 1D and 2D image acquisition control signals are synchronized with each other. The 1D array image sensor captures 1D image information of an object-to-be-tested at different positions along a direction according to the 1D and 2D image acquisition control signals. The 1D image information constitutes 2D image information. Furthermore, a low coherence interferometry is provided.

An optical-fiber measurement system includes an optical transceiver comprising an optical transmitter and an optical receiver. A multi-core optical fiber has a proximal end with a first optical core coupled to the transceiver and a second optical core coupled to the transceiver, and a distal end with the first optical core coupled to a sample path that is configured to convey light collected from a sample positioned external to the multi-core optical fiber and the second optical core coupled to a reference path such that the sample path and the reference path experience mostly a same disturbance along the multi-core optical fiber. The optical receiver is configured to interferometrically detect light from the sample path and light from the reference path.