A multi-channel sensing system is disclosed. The multi-channel sensing system includes a multi-channel sensor connector that wavelength-divides an optical pulse output from a pulsed laser into a plurality of channels in a spectrum domain, transmits each of a plurality of optical sub-pulses generated from the wavelength division to a channel path allocated for each channel in multi-channel paths, multiplexes the plurality of optical sub-pulses passed through the multi-channel paths and outputs an optical signal including the multiplexed optical sub-pulses; and a multi-channel optical phase detector that receives the optical signal output from the multi-channel connector and a reference signal which is synchronized to the pulse laser, and detects a channel-specific electrical signal that corresponds to a timing error between each of the plurality of optical sub-pulses included in the optical signal and the reference signal. At lease one of sensors is connected to at least one of the multi-channel paths.

A multi-channel sensing system is disclosed. The multi-channel sensing system includes a multi-channel sensor connector that wavelength-divides an optical pulse output from a pulsed laser into a plurality of channels in a spectrum domain, transmits each of a plurality of optical sub-pulses generated from the wavelength division to a channel path allocated for each channel in multi-channel paths, multiplexes the plurality of optical sub-pulses passed through the multi-channel paths and outputs an optical signal including the multiplexed optical sub-pulses; and a multi-channel optical phase detector that receives the optical signal output from the multi-channel connector and a reference signal which is synchronized to the pulse laser, and detects a channel-specific electrical signal that corresponds to a timing error between each of the plurality of optical sub-pulses included in the optical signal and the reference signal. At lease one of sensors is connected to at least one of the multi-channel paths.

A phase difference measuring device is provided with a phase conversion device and a detection device. The phase conversion device converts a first laser beam that passes therethrough so that the first laser beam includes a phase distribution of one cycle in an azimuth direction in a cross section of the first laser beam included in an arbitrary virtual plane perpendicular to an optical axis of the first laser beam. The detection device detects an azimuth angle of an intensity centroid of an interference pattern generated by at least a part of a first laser beam that has passed through the phase conversion device, and a part of a second laser beam that derives from a laser beam as seed light from which the first laser beam derives, of which an optical intensity is same as the at least a part of the first laser beam, and detects an inter-beam phase difference of the second laser beam.

A phase difference measuring device is provided with a phase conversion device and a detection device. The phase conversion device converts a first laser beam that passes therethrough so that the first laser beam includes a phase distribution of one cycle in an azimuth direction in a cross section of the first laser beam included in an arbitrary virtual plane perpendicular to an optical axis of the first laser beam. The detection device detects an azimuth angle of an intensity centroid of an interference pattern generated by at least a part of a first laser beam that has passed through the phase conversion device, and a part of a second laser beam that derives from a laser beam as seed light from which the first laser beam derives, of which an optical intensity is same as the at least a part of the first laser beam, and detects an inter-beam phase difference of the second laser beam.

According to the present disclosure, there is provided a device (2) and a method for measuring a wavelength for a laser device. The device (2) for measuring a wavelength for a laser device includes: a first optical path assembly and a second optical path assembly. The first optical path assembly and the second optical path assembly constitute a laser wavelength measurement optical path. The second optical path assembly includes: an FP etalon assembly (11) and an optical classifier (13). The homogenized laser beam passes through the FP etalon assembly (11) to generate an interference fringe. The optical classifier (13) is arranged after the FP etalon assembly (11) in the laser wavelength measurement optical path, and configured to deflect the laser beam passing through the FP etalon assembly (11). The FP etalon assembly (11) allows two FP etalons (FP1, FP2) to share the same optical path for an interference imaging, and therefore a compact structure having a small volume, a simple design, and a high stability are achieved. In cooperation with the optical classifier (13), a precise measurement for a laser wavelength may be achieved, and at the same time a wavelength measurement range is large. It is suitable for an online measurement for a laser wavelength and a corresponding closed-loop control feedback.

Information relating to an etalon is accessed, the etalon being associated with a calibration parameter having a pre-set default value, the etalon being configured to produce an interference pattern including a plurality of fringes from a received light beam, and the information relating to the etalon including first spatial information related to a first fringe of the plurality of fringes and second spatial information related to a second fringe of the plurality of fringes. A first wavelength value of the received light beam is determined based on the spatial information related to the first fringe and an initial value of the calibration parameter. A second wavelength value of the received light beam is determined based on the spatial information related to the second fringe and the initial value of the calibration parameter. The first wavelength value and the second wavelength value are compared to determine a measurement error value.

When the optical system is illuminated with an illumination light flux emitted from one extant input image point, an interference image generated by superimposing an extant output light flux output from the optical system and a reference light flux coherent with the extant output light flux is imaged to acquire interference image data, and thus to acquire measured phase distribution, and this acquisition operation is applied to each extant input image point. Thus, each measured phase distribution is expanded by expanding functions μn(u, v) having coordinates (u, v) on a phase defining plane as a variable to be represented as a sum with coefficients Σn{Ajn.Math.μn(u, v)}. When the optical system is illuminated with a virtual illumination light flux, a phase Ψ(u, v) of a virtual output light flux is determined by performing interpolation calculation based on coordinates of a virtual light emitting point.

When the optical system is illuminated with an illumination light flux emitted from one extant input image point, an interference image generated by superimposing an extant output light flux output from the optical system and a reference light flux coherent with the extant output light flux is imaged to acquire interference image data, and thus to acquire measured phase distribution, and this acquisition operation is applied to each extant input image point. Thus, each measured phase distribution is expanded by expanding functions μn(u, v) having coordinates (u, v) on a phase defining plane as a variable to be represented as a sum with coefficients Σn{Ajn.Math.μn(u, v)}. When the optical system is illuminated with a virtual illumination light flux, a phase Ψ(u, v) of a virtual output light flux is determined by performing interpolation calculation based on coordinates of a virtual light emitting point.

There is provided a method, apparatus and system for calibrating and operating an optical wavemeter. In calibration, training optical signals with known wavelengths are input to a wavemeter, and corresponding photodetector measurements are obtained. Optical parameters of the wavemeter are then estimated based on the measurements. The optical parameters are indicative of a length difference ΔL between two unequal-length waveguides in an optical delay line of the wavemeter; and scattering parameters of a multi-mode interferometer (MMI) coupler of the wavemeter. The estimation process involves a (e.g. golden-section) search to determine one or more output values for at least one of the optical parameters, based on an objective function which indicates a difference expected and actual measurements. The expected measurements are generated based on a numerical model incorporating candidate values for the optical parameters.

A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.