This PDF file contains the front matter associated with SPIE Proceedings Volume 11523, including the Title Page, Copyright information, and Table of Contents.

Snapshot Mueller matrix spectropolarimetry expands on the methods of snapshot Stokes vector (channeled) spectropolarimetry to analyze the polarization properties of materials. While calibration methods for Stokes vector spectropolarimetry are now well-established, their Mueller matrix counterparts are not in the existing literature. After surveying the Stokes vector methods, we show how to expand the calibration methods for the more difficult Mueller matrix spectropolarimetry case and show preliminary measurements.

In a typical interferometric experiment, the overlap between the reference and probe beams produces an intensity pattern composed of fringes. This fringe pattern contains information regarding the interaction of the probe beam with the sample. If the probe beam passes through a polarizing system, it acquires both a dynamic and geometric phase. The former related to the optical pathlength, whereas the latter related to changes in the state of polarization. As a consequence, the fringe pattern suffers a lateral spatial shift and, mainly due to the geometric phase, change its visibility. In this work, we derive simple expressions relating the fringe visibility with the geometric phase and retardance introduced by the polarizing optical system, in terms of the input polarization state. By doing so, we extract the eigenvectors and eigenvalues of the Jones matrix that characterizes the sample. Therefore, our results enable the implementation of a fringe polarimetry technique, i.e., we can infer the polarization properties of the test sample through visibility measurements.

We experimentally investigated the intercore crosstalk of a multicore fiber (MCF) with Bragg grating inscribed in each core. The purpose is to clarify the effect on the three-dimensional curvature measurement based on a multicore fiber Bragg grating (FBG) and two-photon absorption process in a Si-APD that we have been investigating. The experiment was performed by injecting laser light only in the center core of the MCF and measuring the reflected light from the FBGs in the side cores for the cases that the grating section of the fiber is straight or bent. This measurement was also performed for different wavelength. The measurement results confirmed that the crosstalk was small enough to affect the accuracy of the curvature measurement. We also performed curvature sensing based on the proposed method.

An electromagnetic simulation model of microscopic scattering dark-field imaging was built based on the finite difference time domain (FDTD) method. The scattered light distribution of different defect’s size was obtained. Results show the span of distribution curve and the distribution peak are relative to the defect’s width and depth respectively. In the width range of 0.5 μm to 1 μm, there is a linear relationship between the distribution span and the defect’s width. Its goodness of linear fit reaches 0.9. Within the depth range of 0.1μm, the distribution peak linearly changes with the depth. But with the depth becomes deeper, the linear relationship between distribution peak and defect’s depth disappears. The results in this paper can provide instructive reference for the defect’s size inversion.

A method to simulate and design the dark-field imaging scene for optical spherical surface imperfection is proposed based on raytracing. Rays emit from the finite aperture camera model to the world space, split at the optical surface and finally obtain luminance from light sources. Thus the image function can be solved by raytracing and Monte Carlo integration of luminous flux. A typical dark-field imaging scene is presented, of which realistic images of various kinds of lens are rendered. The simulated images can well predict where the spots of light source locate and reveal imperfections. At last, corresponding adjustments are implemented to eliminate the influence of second surface.

The high & low refractive index (Nb₂O₅/SiO₂)² multi-layer films were deposited by E-gun evaporation with ion-beam assisted deposition (IAD) on flexible PET substrate. The optical property and anisotropic residual stress were investigated. The residual stress of each layer film was measured step by step with self-made shadow moiré interferometer. The experimental results showed the optimal oxygen flow of Nb₂O₅ and SiO₂ were 20 and 25 sccm, respectively, for the absorption coefficient less than 10^-3. The principle stresses were changed from tensor to compressor stress from 6,665 to - 916MPa for one layer to (HL)² four layers. The shearing stresses were all tensor stresses from 5,876 to 406 MPa for one layer to (HL)² four layers. The multi-layer films real reduced the residual stress.

New type of optical system for low-coherence digital holography with a close set of two wavelengths is proposed to measure a shape measurement of a curved surface object with a height of several-tens micrometer. The optical system simultaneously captures the object image with two wavelengths.

We demonstrate the photo-thermal (PT) spectroscopy of a 1.53-μm acetylene line using an optical heterodyne interferometer (OHI). A double-pass acousto-optic modulator is used as the frequency shifter and beam splitter in the OHI. The PT excitation beam overlaps with the probe beam of OHI, and the PT-induced phase change on the probe beam is detected by the OHI. Due to the nearly equal path length of the OHI scheme, we can observe the PT signal without using feedback control to maintain the path difference of the OHI arms.

In a dark channel of more than 15 m, a standard A light source was used to simulate a motor vehicle's headlight, and a Nikon D750 digital camera was used as a light receiver. While the observation angle α was 0.33°, the entrance angle component β1 was −4°, the entrance angle component β2 was 0°, and the coefficients of retroreflection of the retroreflectors were measured. The entrance angle component β1 changed from −4° to 0°, and the chromaticity coordinates of retroreflectors were then measured. Experimental results show that the maximum measurement error of the coefficient of retroreflection is −2.09%, and the measured results of the chromaticity coordinates meet the national standard of retroreflective sheeting for traffic control. Obviously, the RAW data output from the camera has a linear association with the luminous flux on the surface of retroreflectors, which can be used to calculate the coefficients of retroreflection and the chromaticity coordinates.

Paper presents the computer simulation of laser gyros behavior under vibrations at the designing early stages. It allows for savings on repetitive tests and re-designing, finally improves reliability and economic efficiency of development and production.

Fast fringe projection 3D measurement system using a generalized phase-shifting method with a continuous fringe scanning scheme is proposed. Fast measurement can be performed owing to the continuous fringe scanning scheme. An object phase is obtained by a generalized phase-shifting method using normalization of randomly phase-shifted deformed fringe images. We conduct experiments on measurement of small deformation in muscle tendon of human hand during mouse operation. Experimental results indicate that the proposed method can quantitatively measure the deformation of human hand.

An interferometric line sensor in a Michelson configuration without a transmission sphere is employed for annular subaperture stitching interferometry to measure spherical and aspherical surfaces. The misalignments between the subapertures, which are caused by positioning error induced wavefront aberrations, are corrected employing a machine learning based Zernike polynomial fitting in the overlapping regions.

Interferometry is a widely used optical measurement technique. We can estimate the physical parameters of the measured object by analyzing the phase of the fringe pattern obtained by interference imaging. However, when the measurement object has spherical surface, the interferogram always contains closed fringes which the traditional analysis methods are difficult to handle. Therefore, we use several common deep learning networks to learn the closed fringe patterns and their phases, evaluate and choose the appropriate network to build an end-to-end phase analysis system for a single closed fringe pattern. The experimental results show that the constructed deep learning network model has excellent phase recovery effect on simulation closed fringe patterns, and can estimate the curvature radius of the spherical surface accurately.

Point diffraction interferometer (PDI) has become the most promising measurement tool since it is firstly proposed by Linnik and its key component used to generate the reference wave can be called as the reference wave source (RWS). A new RWS based on the silicon nitride (SiN) waveguide is now proposed, aimed at providing a spherical reference wave with high NA and high accuracy. Simulation results show that the PV and the RMS of the reference wave generated by the waveguide RWS are 2.86×10^-4λ (λ=532nm) and 4.83×10^-5λ respectively, and the maximum light transmittance of this RWS could reach 24%. In addition, the NA of the reference wave reaches up to 0.58.

In the nano/micro manufacturing, in-process optical inspection plays one of the most important roles for producing the advanced products with high reliability, because it has several practical advantages typified by nondestructiveness, high-throughput characteristics, and so on. Optical measurement methods, however, essentially restrict its spatial resolution due to the diffraction limit, which means that finer structures less than half of the wavelength of optical wave from the objects to be inspected, cannot be observed. This resolution limit of the optical measurement method is a critical problem especially for the nano/micro manufacturing process, where the features of submicrometer fine structures should generate special functions. This critical limit about spatial resolution can be physically explained by focusing on light energy localization property. As shown in Table1, light energy can be mainly classified into the following three types of localizations: (1) Evanescent light generated under the total internal reflection. (2) Near-field light existing in the vicinity of tips of the near-field optical probe. (3) Interference intensity distribution of standing wave (mainly generated with two beam interference) and focusing beam (generated with multiple-beam interference), both of which consist of free-space propagating light (freely propagating light) waves. Physical principles for spatial resolution improvement are essentially different based on these types of light energy localization. In order to develop the effective optical inspection beyond the diffraction limit, it is important to recognize their super resolution property depending on their light localization. Evanescent light is known as effective near-field light illumination for surface, which can be applied to near-field scanning optical microscopic inspections.

Imaging ellipsometry (IE) possesses characteristics of both single-point measurement ellipsometry and optical microscopy. To obtain quantitative measurement, it is very important for design of the spectroscopic imaging ellipsometer to employ a correct imaging system, solve non-uniformities of optical components. Here, we introduce a reflection imaging system, measurement noises due to non-ideal optical components, and describe solutions of problems.