This PDF file contains the front matter associated with SPIE Proceedings Volume 11927, including the Title Page, Copyright information, and Table of Contents.

Single pixel imaging (SPI) is considered to be a promised technique in computational imaging because of some advantageous features and suitability for signal restoration with compressive sensing, deep learning, and so on. In this presentation, the principle of SPI is explained. In the SPI, two dimensional spatial modulation for optical signals is an important operations. A procedure for renewal of the modulation has been proposed. This procedure with spatial pattern shift is suitable for a some specific implementation based on SPI. Especially, it is useful for imaging of a target moving at a constant velocity. This procedure is introduced and usefulness of it is discussed.

In demand for minute defect inspection, it is required to detect weak scattered light caused by small defects. Ghost imaging (GI) is known for its high sensitivity and high noise resistance method. However, it requires many measurements to obtain a high-quality image because GI is the correlation-based imaging method. Reducing the number of measurements, a method combined with deep learning has been proposed. In order to improve the estimation accuracy using CNN, we propose to parallelize the convolutional layers. Parallel convolutional layers can efficiently extract both local and global features, which contributes to the improvement of estimation accuracy. In this report, we show that parallel CNN is more accurate than conventional CNN by experiments.

A new type camera constructed by an active light source and a high frame rate imaging sensor was introduced for recording three-dimensional image of the object. The intensity of the light encoded by the compressive sensing technique and a gigahertz range carrier wave generator was illuminated the object. The imaging sensor with kilo-frame rate range synchronized with the light source was used for sampling the encoded light wave reflected from object. The waveform of the carrier wave can be reconstructed with few frames by the compressive sensing technique. Resultantly, the 3D image of the object was precisely extracted from the phase of the carrier wave in very short time with few frames.

Computer simulation is performed for pulsed laser heating of a surface with submicrometer-sized truncated-coneshaped peaks and holes. Transient temperature field is calculated, and the visual appearance of the surface roughness elements is modeled with the laser-induced thermal emission. The results of calculations reveal special features in visual appearance of peaks on the surface which opens a possibility to distinguish between different surface elements. The calculations also predict 20 fold variations of local thermal emission radiant exitance of rough surfaces. The experiments confirm the presence of the exitance variations on rough surfaces of carbon materials.

Luminescent Si nanocrystals were prepared from rice husks and the optical properties and structure analysis were studied. By the transmission electron microscope observation of the Si powder from rice husks, aggregates that are composed of Si nanoparticles with crystalline structure were confirmed. Room temperature PL with near infrared-red regions were observed from the Si nanocrystals. From the measurements of the PL decay curves, order of the life time were sub-micro seconds and that depended on the wavelength of the luminescence. These results indicates that the origin of the PL from Si nanocrystals made from rice husks is quantum size effect. Preparation of luminescent Si nanocrystals from rice husks is an effective method for recycling rice husks.

Tapered fibers with a diameter of sub-micrometer to several micrometer show various optical characteristics, and the diameter is the most important parameter. To guarantee their functions, it is necessary to measure the fiber diameter with high precision during manufacturing. In this research, we propose an in-process measurement method of the diameter of sub-micro-optical fiber. The proposed technique is based on analyzing optically scattered light generated by standing wave illumination. First, we show the scattering characteristics of sub-microfibers using numerical simulation based on finite element method (FEM). From the result of simulation, it was revealed that the optical fiber of 100 nm in diameter can be evaluated with the standing wave illumination.

In recent years, unique functions of nano-periodic structures have attracted much attention, and there is a need for processing techniques with high processing efficiency and flexibility. Therefore, we focused on Talbot lithography, which has excellent processing efficiency for periodic structures. In this paper, we use hologram-assisted Talbot lithography to improve the processing flexibility of Talbot lithography. Hologram-assisted Talbot lithography is a method to improve the processing flexibility of structures by using CNN to estimate the incident light distribution. In order to improve the accuracy of the hologram-assisted Talbot lithography method for controlling periodic structures, we studied the learning of CNN. And we showed that the shape and period of the structure can be controlled by using CNN.

We proposed an optimization method of a hologram in holographic laser processing. The laser beam was diffracted by a designed computer-generated hologram (CGH) displayed on a liquid-crystal-on-silicon (SLM), and then formed spatially shaped three-dimensional optical pattern which detected by a CCD image sensor at different focal position for continuously optimizing with the weighted iterative Fourier transform (WIFT) algorithm. The uniformity of the pattern was increased from 11% to 95%, which was also well proved by the corresponding 3D processing results. This method provides the holographic laser processing system with high-stability, that is, the ability to dynamically compensate for system imperfections, and has the ability to be suitable for a wide range of high-precision, high-throughput applications in the field of 3D manufacturing.

We developed an optical caliper for measurement of 3D profiles of openings. The optical caliper consists of a semiconductor laser, a right circular conical mirror, and a camera with a wide-field lens. The distance from the mirror and the camera is changeable, which leads to increment of the measurement range with one system. The 3D inner profile of an art craft was measured with this system.

A theoretical model is developed to study the dynamic gain in the transmitted optical power through a 3D printed photopolymer waveguide. The given model shows that the solvent molecules diffused in the photopolymer and develops a swelling layer which acts as cladding. Formation of the cladding layer results in reduction of surface scattering losses and increase in the optical power. A methacrylate-based photopolymer waveguide is 3D printed using stereolithography as a single-step fabrication technique. Two solvents vapor: methanol and ethanol were tested with the given waveguide. An increase in the transmitted optical power is experimentally recorded and compared with the theoretical results to verify our model. This information is significant for fabricating integrated optical devices for sensing applications using photopolymers.

A single-step approach based on heating and pulling single-mode fiber optics via a modulated-arc discharging process is investigated, resulting in microfiber long period gratings (MF-LPGs) structures. In this process, a modulated-arc signal controls the effective axial tension over the fused fiber. Consequently, both microfiber and periodic down-tapers are generated simultaneously through a single-step. This pulse signal period determines the pitch of the induced gratings and adjusts the resonance wavelength of the MF-LPGs. The sample with the diameters of microfiber and tapers equal 30 μm and 15 μm, respectively, provides a high resonance dip up to 26 dB at the wavelength of 1547 nm. The proposed low-cost and fast fabrication technique should be useful for in-line microfiber devices and sensors based on MF-LPGs.

In this presentation, we discuss noise floor comparisons of an optical displacement measuring interferometer between air and vacuum environments. A heterodyne interferometer and its phasemeter, with the resolution of 10-6 radian, implemented in a field programmable gate array (FPGA) are utilized for the comparison. A heterodyne laser source consists of a frequency stabilized He-Ne laser and two acoustic optic modulators (AOMs). The interferometer optics and a piezoelectric (PZT) flexure stage which drives the moving retroreflector of the interferometer are placed in a vacuum chamber. In the vacuum environment at 3 mPa, the noise floor of 1 pm/ÖHz or less is attained in the frequency range of 0.01 ~ 100 Hz.

We present a method of using computer-generated hologram (CGH) to measure the radius of curvature of large aperture long-focal-length lens. In this method, a large aperture transmission CGH is used as a transmission sphere to generate the test and reference wavefronts by means of diffraction. To verify the feasiblity of this method, a 450 mm × 450 mm transmission CGH is designed and fabricated for measuring the radius of 440 mm × 440 mm spatial filter lens. Experimental results and error analysis show that the CGH test method features high accuracy and good repeatability.

In this study, a diffraction grating was used for generating laser parallel fringes in a camera. Phase analysis method using those laser parallel fringes were used to measure out-of-plane displacement. A green laser of line projection function, a diffraction grating and an industrial camera were used as an experimental device. Object images with laser parallel fringes projection before and after displacement were taken by the camera. Laser parallel fringes can be generated in a camera and displacement was successfully measured by phase analysis of laser parallel fringes.

The task of optical 3D profilometry is to measure the value of spatial coordinate of one or more surface points of an object. The value of measured coordinate is obtained from one or more intensity values that are recorded by a detector. The way in which the resulting intensity is generated depends on whether the surface is optically smooth or rough. The property of a surface to be optically smooth or rough depends on the mechanical properties of the surface and on the parameters of the optical system. We present a detailed analysis of the conditions on which a surface can be classified as optically smooth or optically rough. It is also discussed how the optically smooth surface and the resolved mode are related.

For on-site analysis in the remote world, we proposed the ultra-miniature and low-price LWIR hyperspectral camera and the ultrasonic-assisted spectroscopy. We proposed 3 kinds of Fourier transform spectroscopic imager whose optical configuration were the near-common-path phase-shift interferometer. And to measure suspending solutions and biological samples without preparations like smart toiles and non-invasive blood glucose sensors, we proposed 2 types of the ultrasonic-assisted spectroscopy. We successfully recognized the absorbance peaks at 9.25μm and 9.65μm of glucose.

Recently, it is required to improve the fringe projection device to develop a compact and fast 3D shape measurement. In this study, a fringe projection method using a linear LED device and a cylindrical lens array to improve the LSSM is proposed. In the case of a conventional light-source-stepping method, the half of the emitted power is wasted at the grating plate. In contrast, in the case of the proposed method, almost emitted power can be used as the projected fringe pattern. It was confirmed with an experiment.

The optical-based super-resolution, non-invasive method is preferred for the inspection of surfaces with massive microstructures widely applied in functional surfaces. The Structured Illumination Microscopy (SIM) uses standing-wave illumination to reach optical super-resolution. Recently, coherent SIM is being studied. It can obtain both the super-resolved intensity distribution and the phase and amplitude distribution from the sample surface. By analysis of the phase-depth dependency, the depth measurement for microgroove structures with coherent SIM is expected. FDTD analysis is applied for observing the near-field response of microgroove narrower than the diffraction limit under the standing-wave illumination. The near-field phase shows depth dependency in this analysis.

A resolution evaluation of displacement measuring interferometer using a sinusoidal phase modulation (SPM) and a modified phase-locked loop (PLL) is discribed in this presentation. Displacement measuring interferometer with frequency stabilized light source has advantages of high resolution and traceable to the definition, and the combination of the SPM and modified PLL is one of the interpolation methods to improve the resolution of displacement measuring interferometer. The resolution is evaluated by noise floor measurement and small step displacement measurement. The results show that the measurement system could observe step displacement as small as 0.1 nm, but the noise floor contains drift and noise peaks at certain frequencies.

We present a demodulation approach for a rotating polarizer-analyzer polarimeter dedicated to retardance measurements. Through the Mueller matrix approach and the theoretical Fourier transform, we developed a demodulation algorithm considering the two linear polarizers' initial orientation as calibration. We present experimental results showing the feasibility of our proposal.

This paper describes a new approach for large-scale thin film thickness mapping based on dynamic spectroscopic ellipsometry. The proposed system can provide a real time thin film uniformity measurement capability with high precision. We expect the proposed scheme can be applied for various large-scale thin film deposition process applications such as roll to roll manufacturing where real time process uniformity monitoring becomes crucial.

Spectroscopic polarization measurement and control using channeled spectrum has several unique features and is useful for various spectroscopic instruments. It utilizes the strong dispersion characteristics in polarization retardation of high-order retarders so that the polarization modulation can be made without using mechanical or active elements for polarization modulation. In this presentation, we describe its principle, basic features, and several applications including a spectroscopic ellipsometer and ultrafast rotations of beam profile and polarization.

Spectroscopic polarization measurement and control using channeled spectrum has several unique features and is useful for various spectroscopic instruments. It utilizes the strong dispersion characteristics in polarization retardation of high-order retarders so that the polarization modulation can be made without using mechanical or active elements for polarization modulation. In this presentation, we describe its principle, basic features, and several applications including a spectroscopic ellipsometer and ultrafast rotations of beam profile and polarization.

The research proposal was used tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) as the high and low refractive index for the multilayer anti-reflection (AR) films were deposited on a flexible polyethylene terephthalate (PET) by electron-beam evaporator with ion-beam assisted deposition (IAD). The optical and stress properties of these multilayer (Ta2O5/SiO2)2 films were investigated. A homemade Phase shadow moiré interferometer was used to measure the stresses of single and multilayer films. The experimental results show the optimal oxygen pressure of Ta2O5 and SiO2 were 8 and 25 sccm, respectively for the multilayer AR coating with electron-beam evaporator. The residual stress of the multilayer film stacks changed gradually from tension to compression stresses which +3,167 MPa was for the first layer and -438 MPa for the fourth layer.

Error calibration is one of the most important factors to realize the quadri-wave lateral shearing interferometer (QWLSI) with high accuracy. The misalignment errors of QWLSI, such as the tilt of grating and the tilt of charge coupled device (CCD), will affect the measurement accuracy. The astigmatism errors induced by the tilt of grating and CCD during the alignment process of QWLSI, which are neglected in previous studies, are analyzed and presented in analytical expressions in this paper. Firstly, the additional phase difference in X and Y directions induced by the tilt of grating and CCD are analyzed using the optical wave interference theory. Representing the phase difference in the two directions and the test wavefront with the combinations of Zernike polynomials respectively, we further obtain the analytical expressions between the Zernike coefficients of the phase difference and the Zernike coefficients of the test wavefront, according to the wavefront reconstruction theory. Then the analytical expressions for the measurement errors induced by the tilt of grating and CCD, which are mainly astigmatism, can be obtained. The analytical results show that the misalignment induced astigmatism errors are inversely proportional to the shearing ratio and proportional to the tilt angle of grating and CCD. The alignment experiment of a home-made QWLSI under null test condition is conducted to verify the correctness of the theoretical analysis. With different shearing ratios for the QWLSI, the astigmatism errors, which are induced by the tilt of grating in experimental results, are consistent with the theoretical analysis results. This paper can provide technical support for the alignment of QWLSI with small shearing ratio and high precision.

Good robustness and fast processing speed are the two main aspects of phase unwrapping algorithm for two-dimensional interferogram. Multi-lateral shearing interferometry requires the use of multidirectional differential wavefronts to reconstruct the wavefront to be measured, which leads to higher requirements on the phase unwrapping speed of the interferogram. The quality map guided algorithm is a reliable algorithm in the phase unwrapping of two-dimensional interferogram. In this paper, the computer unified device architecture (CUDA) programming platform is used to realize the parallel processing of the phase derivative variance map, the maximum phase gradient map, and the pseudo-correlation quality map, in order to improve the speed of phase unwrapping. Parallel calculations are respectively performed on the variance of the wrapped phase gradient in the horizontal and vertical directions in the phase derivative variance map, the wrapped phase gradient in the horizontal and vertical directions of the maximum phase gradient map, and the sine and cosine values of the wrapped phase in the pseudo-correlation quality map. Finally, the CUDA instructions are used to distribute the calculation task and complete the parallel calculation of the quality map. The computer-generated multi-lateral shearing interferograms are used for simulation analysis. The results show that for the same interferogram of 512×512 pixels, the processing speed can be approximately increased by 3 times on the Graphics Processing Unit (GPU) by performing parallel calculation to generate the quality maps. The fastest parallel processing time is 7.34ms for generating the derivative variance map. As the number of pixels increases, GPU processing speed becomes more advantageous, far exceeding that of CPU. Using the self-made quadriwave lateral shearing interferometer, the speed and accuracy of the three quality map guided phase unwrapping algorithms are compared and analyzed. The experimental results show that the derivative variance quality map, which shows the fastest parallel processing speed and the smallest measurement error among the three kinds of quality maps, is more suitable for the parallel phase unwrapping of multi-lateral shearing interferograms.

Star test polarimeter can map the polarization state of incident light into an intensity distribution of the detection plane by placing a space-variant phase retarder (SVPR) in the pupil plane of an optical system, which can achieve fast acquisition of polarization information of incident light from a single irradiance image. However, subjected by the system’s alignment and vibration, star test polarimetry need the calibration scheme with high robustness and fast speed. This paper develops a fast calibration method for Star test polarimetry by measuring three intensity distribution of orthogonal polarization state and an intensity distribution of left-handed circular polarization. Experimental results show that the proposed method, combined with normalized least square (NLS), can rapidly calibrate the theoretical model to accurately measure the polarization state of incident light.