Methods and systems for inspection of an object include the use of spectroscopic techniques for the detection of unwanted particles on an object's surface, based on the different responses of the unwanted particles as compared with the object to be inspected due to their different materials. Time resolved spectroscopy and/or energy resolved spectroscopy of secondary photon emission from the surface of the object can be used to obtain Raman and photoluminescence spectra. The objects to be inspected can for example be a patterning device as used in a lithographic process, for example a reticle, in which case the presence of metal, metal oxide or organic particles can be detected, for example. The methods and apparatus are highly sensitive, for example, being able to detect small particles (sub 100 nm, particularly sub 50 nm) on the patterned side of an EUV reticle.

Object inspection systems and methods

The invention discloses a phase diaphragm (2) capable of measuring optical nonlinearity of material, comprising a phase object (13), wherein the phase delay between the phase object (13) and the phase diaphragm (2) is Pi/2; the phase object (13) is a symmetrical square. The invention can effectively measure and distinguish the size and symbol of the third-order nonlinear refraction coefficient of a medium without influencing the measuring sensitivity.

Phase diaphragm capable of measuring optical nonlinearity of material

The invention discloses a phase object Z-scan-based pump-probe method, which includes the following steps: an incident laser beam is split into two beams, the beam with high intensity is pump light, the beam with low intensity is probe light, and the pump light is delayed and focused on a non-linear sample to be tested, so that the sample to be tested, which is in the ground state, generates non-linear absorption and non-linear refraction; the sample to be tested is located on the focal plane of a lens in a probe light path, a round diaphragm and a round baffle, the centers of which are superposed with the optical axis, are placed at a far-field position in the probe light path behind the sample to be tested, the emergent probe light is split into two beams by a spectroscope, one of the beams directly enters a first probe, and the other beam enters a second probe after passing through the diaphragm and the baffle. A measuring system which operates according to the method is highly sensitive and can simply process data, non-linear absorption and non-linear refraction can be measured simultaneously rather than separately, and the method has the advantages of accurate measurement results and the like.

Phase object Z-scan-based pump-probe method

The present invention discloses application of a multi-channel optical nonlinearity measurement technology to measure the third-order nonlinear refraction coefficient of a medium. According to the present invention, with numerical simulation, a linear relationship is formed in the range of 0-0.65; in the experiment, the results of a sample to be measured and a standard sample can be directly measured, and by using the linear range, the third-order nonlinear refraction coefficients of a plurality of samples to be measured can be measured through the measuring, such that the complex fitting calculation required by the original single-4f system is avoided; and the experiment results verify that the method of the present invention is correct.

Multi-channel material optical nonlinearity measurement method

The invention discloses a high-sensitivity frequency domain filtering baffle plate Z-scan method for measuring the material nonlinearity, and belongs to the fields of nonlinear photonic material and nonlinear optical information processing The method of the invention comprises: the focus of a lens forms an image through another lens, and a filtering pinhole is arranged at the point of the image; and a circular diaphragm forms an image through a lens set formed by the above two lenses, and a coaxial circular baffle plate is arranged in the image plane During the action of pulse laser, a sample moves from side to side near the focus of the lens Through measuring the non-linear transmittance of an opening, the baffle plate, and the filtering pinhole, the non-linear absorption coefficient and the non-linear refraction coefficient of the material can be determined The method of the invention is characterized by simple work measurement system optical path, obvious stray light influence filtering effect, high measuring sensitivity, and simple data processing, and can measure non-linear absorption and non-linear refraction at the same time

High-sensitivity frequency domain filtering baffle plate Z-scan method for measuring material nonlinearity

The invention discloses a pump detection method based on 4f phase coherence images. Wherein, the laser output by a laser is divided into a pumping light and detecting light; the pumping light is focused after a time-delay platform on a non-linear sample to generate non linearity; the detecting light detects the change in the pumping-light induced non-linear sample, and is recorded by a CCD. By different time delays in the pumping light, the change in the phase and strength of the detecting light emitted from the sample reflects the distribution of particles in the sample at different time periods, so that the absorption sections and service lives and refractivity volume of each energy level are determined. The invention is of simple optic path, the theoretic processing is simple, the single-phase measurement reduces the optic accumulation; the absorption and refracting pumping are completed at the same time without individual measurements, and the size and symbol of non-linear absorption and refraction can be measured concurrently, the sensitivity on the random fluctuation of the laser beam is low, and the measurement results are accurate.

Pumping detecting method based on 4f phase coherent imaging

The invention discloses an optical nonlinear method which is based on the measuring materials of a 4f phase and coherent imaging system. The 4f phase and coherent imaging system divides incident laser into two beams through a beam splitting prism; wherein, one beam comes into a measure optical path as a probe light and is collected by a CCD camera after passing 4f system and the other beam is a reference light and is collected by the same CCD camera after coming into a reference light path; samples are arranged at a Fourier plane of the 4f system of the measure optical path. The invention is characterized in that the reference light path is the 4f system; and the outgoing direction of the reference light path and the outgoing direction of the measure optical path are parallel. The improvement of the reference light path leads the invention to get the distribution situation of an incident pulse space on the incident plane at the same time of getting pulsed laser energy on the samples and to measure the nonlinear refractive index under the condition of the unstable spatial distribution of light spots with the simple optical path, the quick testing speed, the accurate results and the convenient data processing.

Optical non-linear method for measuring material based on 4f phase coherent imaging system

Phase diaphragm for 4f phase coherence imaging system

The utility model discloses a pump detection device based on 4f phase incoherent imaging, which is characterized in that the utility model essentially consists of an optical laser, a beam splitter, a detection light path and a pump light path. The beam splitter splits laser pulse sent from the optical laser into the detection light path and the pump light path. The detection light path comprises a beam expanding system, a 4f system and a record system; samples to be detected are positioned on the focal plane of the 4f system. The pump light path comprises a steering element and a delayed light path. The output of the pump light path focuses on the samples to be detected. The included angle (Beta) of the detection light path and the pump light path on the samples to be detected is between 1.5 degrees and 10 degrees. The device of the utility model does not have rigorous requirement for precision of light paths; absorption pump detection and refraction pump detection are finished simultaneously; during the whole detection process, the samples does not need to move; monopulse measurement reduces chemical cumulative effect and has simple measurement process and low sensitiveness to the random fluctuation of laser beans; measurement result is precise and measurement speed is fast.

Pump detecting device based on 4f phase coherent imaging

The invention discloses a method which can measure the optical nonlinearity of a medium interface and apply the reflected light to measure the film optical nonlinearity, which belongs to the nonlinear photonics material and nonlinear optical information processing fields. An incident laser light is divided into two ways through a beam splitting prism, one way is a probe light which enters a measure optical path and is collected by a CCD camera after passing through a 4f phase coherent imaging system; and the other way is a reference light; and the method is characterized in that: the sample is placed on a focal plane of a first convex lens of the measure optical path in a reflection mode, a second convex lens having the same focal length with the first convex lens is positioned at the one-time focal length part along the transmission direction of the reflected light, thereby forming the reflection 4f phase coherent imaging system; and the measurements include two parts of energy calibration and optical nonlinearity measurement. The method has the advantages of convenient measurement, simple optical path, non movement of sample, single pulse measurement, being not easy to damage medium surfaces, and having low requirements to stability of light source energy and space.

Yinglin Song

Papers

Pumping detecting method based on 4f phase coherent imaging

Optical non-linear method for measuring material based on 4f phase coherent imaging system

Phase diaphragm for 4f phase coherence imaging system

Pump detecting device based on 4f phase coherent imaging

Method for measuring optical non-linear 4f phase coherent imaging