A Remote Raman System and Its Applications for Planetary Material Studies

A remote Raman prototype with a function of excitation energy adjusting for the purpose of obtaining a Raman signal with good signal-to-noise ratio (SNR), saving power consumption, and possibly avoiding destroying a target by high energy pulses, which may have applications for Chinese planetary explorations, has been setup and demonstrated for detecting different minerals. The system consists of a spectrograph equipped with a thermoelectrically cooled charge-coupled device (CCD) detector, a telescope with 150 mm diameter and 1500 mm focus length, and a compact 1064 nm Nd:YAG Q-switched laser with an electrical adjusted pulse energy from 0 to 200 mJ/pulse. A KTP crystal was used for second harmonic generation in a 1064 nm laser to generate a 532 nm laser, which is the source of Raman scatting. Different laser pulse energies and integration time were used to obtain distinguishable remote Raman spectra of various samples. Results show that observed remote Raman spectra at a distance of 4 m enable us to identify silicates, carbonates, sulfates, perchlorates, water/water ice, and organics that have been found or may exist on extraterrestrial planets. Detailed Raman spectral assignments of the measured planetary materials and the feasible applications of remote Raman system for planetary explorations are discussed.

Automatically Tightening Tiny Screw Using Two Images and Positioning Control

This paper describes how to tighten M1.4 screws by controlling a manipulator. The whole process is based on a human–machine interface designed using Visual Studio C++ to run image processing algorithms and control the position of a manipulator. Two charge-coupled device cameras are used. One is fixed on the stationary frame above screw holes and used to take pictures of the holes. The positions of the holes are determined using image processing algorithms and then transformed into the coordinate system of the manipulator by using coordinate transformation. The other camera, installed on the end effect of the manipulator, photographs the screw hole to fine-tune the position of the manipulator, improving positioning control. The image processing methods including grayscale, Gaussian filter, bilateral filter, binarization, edge detection, center of gravity, and minimum circumcircle are used to find the center coordinates of the target holes. Experimental study shows that M1.4 screws can be tightened into the target holes with the manipulator.

A super-grayscale and real-time computer-generated Moiré profilometry using video grating projection

By using the time-division multiplexing characteristics of the projector and the integral exposure characteristics of the charge coupled device (CCD) camera, a super-grayscale and real-time computer-generated Moiré profilometry based on video grating projection is proposed. The traditional digital static grating is of 256-grayscale at most. If an expected super-grayscale grating with a maximum grayscale of 766 is designed and divided into three 256-grayscale fringe patterns with balanced grayscale as far as possible, they can be synthesized into a repeated playing video grating instead of the traditional static grating. When the video grating is projected onto the measured object, as long as the exposure time is set to three times the refresh cycle of the video grating, the super-grayscale deformed patterns in the 766-grayscale can be captured with a 10-bit CCD camera, so that the deformed patterns are realistic. The digital error in computer-generated Moiré profilometry is effectively reduced. In addition, this method can expand the linear range of the deformed pattern by 20% in computer Moiré profilometry. Therefore, the proposed method has the perspectives of high accuracy and real-time measurement. Theoretical analysis and experimental results demonstrate the validity and capability of the proposed method.

Parametric Study of Proton Acceleration from Laser-Thin Foil Interaction

We experimentally investigated the accelerated proton beam characteristics such as maximum energy and number by varying the incident laser parameters. For this purpose, we varied the laser energy, focal spot size, polarization, and pulse duration. The proton spectra were recorded using a single-shot Thomson parabola spectrometer equipped with a microchannel plate and a high-resolution charge-coupled device with a wide detection range from a few tens of keV to several MeV. The outcome of the experimental findings is discussed in detail and compared to other theoretical works.

Wide-field photothermal reflectance spectroscopy for single nanoparticle absorption spectrum analysis

Photothermal imaging is useful for detecting individual nanoparticles and obtaining the absorption spectra. This study presents a wide-field photothermal reflectance spectroscopy technique achieved by incorporating a pump beam, a probe beam, and a charge-coupled device (CCD) camera into a commercial microscopic setup. The presented design does not require precise alignment between the pump and the probe beams and enables the observation of numerous individual nanoparticles during image acquisition. Despite the use of a simple imaging processing method, i.e., a four-bucket method using a CCD camera, sufficient sensitivity for the spectral imaging of a single gold nanorod (20 nm diameter and 84 nm length) is demonstrated. Numerous individual nanoparticles within a wide field of view (240 μm × 180 μm) are detected in an image captures at an imaging measurement speed of 0.02 mm2 min−1. Furthermore, the proposed photothermal reflectance spectroscopy technique can detect the variation in the absorption peak of the measured spectra depending on the aspect ratio of individual nanoparticles within a spectral resolution of 1 nm.

Air-Based Contactless Wafer Precision Positioning System

This paper presents the development of a contactless sensing system and the dynamic evaluation of an air-bearing-based precision wafer positioning system. The contactless positioning stage is a response to the trend seen in the high-tech industry, where the substrates are becoming thinner and larger to reduce the cost and increase the yield. Using contactless handling it is possible to avoid damage and contamination. The system works by floating the substrate on a thin film of air. A viscous traction force is created on the substrate by steering the airflow. A cascaded control design structure has been implemented on the contactless positioning system, where the inner loop controller (ILC) controls the actuator which steers the airflow and the outer loop controller (OLC) controls the position of the substrate by controlling the reference of the ILC. The dynamics of the ILC are evaluated and optimized for the performance of the positioning of the substrate. The vibration disturbances are also handled by the ILC. The bandwidth of the system has been improved to 300 Hz. For the OLC, a linear charge-coupled device has been implemented as a contactless sensor. The performance of the sensing system has been analysed. During control in steady-state, this resulted in a position error of the substrate of 12.9 μm RMS, which is a little more than two times the resolution. The bandwidth of the OLC is approaching 10 Hz.

Detection of Electrical Circuit in a Thin-Film-Transistor Liquid-Crystal Display Using a Hybrid Optoelectronic Apparatus: An Array Tester and Automatic Optical Inspection

In this study, we developed a high-resolution, more accurate, non-destructive apparatus for refining the detection of electrode pixels in a thin-film-transistor liquid-crystal display (TFT-LCD). The hybrid optoelectronic apparatus simultaneously uses an array tester linked with the automatic optical inspection of panel defects. Unfortunately, due to a tiny air gap in the electro-optical inspector, the situation repeatedly causes numerous scratches and damages to the modulator; therefore, developing alternative equipment is necessary. Typically, in TFT-LCDs, there are open, short, and cross short electrical defects. The experiment utilized a multiple-line scan with the time delay integration (TDI) of a charge-coupled device (CCD) to capture a sharp image, even under low light, various speeds, or extreme conditions. In addition, we explored the experimental efficacy of detecting the electrode pixel of the samples and evaluated the effectiveness of a 7-inch opaque quartz mask. The results show that an array tester and AOI can detect a TFT-LCD electrode pixel sufficiently; therefore, we recommend adopting the hybrid apparatus in the TFT-LCD industry.

The Relationship between Tribo-Magnetization and Wear State during Reciprocating Sliding

In order to investigate the relationship between tribo-magnetization and wear phenomena, a series of sliding-friction tests were carried out using a pin-on-block reciprocator type device, which was specially designed to generate sliding friction and to detect magnetic fields. The tribological behavior was observed by a charge-coupled device (CCD) camera in real time, and the magnetic signal was detected by using a two-axis magnetic sensor. It was found that as the friction continues, both the tangential and the normal components of magnetic field on the material surface increase gradually, and that both the average value of the tangential magnetic field ΔH(x)mean and the peak-to-peak value of the normal magnetic field Vpp at the wear scar clearly reflect changes of the wear state. Furthermore, in order to better understand the tribo-magnetization phenomenon, the changes of surface morphology and wear debris in different wear stages were analyzed. Moreover, an improved magnetic dipole model that considered the distribution of magnetic charges on the worn surface was established. This model can successfully describe the tribo-magnetization phenomenon during the stable wear stage, and should be useful for characterizing frictional wear phenomena in the future.

Bayesian Super-Resolution of Spectroscopic Data

The resolution of spectroscopy, which delivers valuable insights and knowledge in various research fields, has sometimes been limited by the number of multi-channel detectors employed. For example, in Raman spectroscopy using charge coupled device (CCD) detectors, the resolution is limited by the number of the CCD arrays and it is difficult to achieve spectroscopic data acquisition with high resolution over a wide range. Here we describe a methodology to increase the resolution as well as signal-to-noise (S/N) ratio by applying Bayesian super-resolution in the analysis of spectroscopic data. In our present method, first the hyperparameters for the Bayesian super-resolution are determined by a virtual experiment imitating actual experimental data, and the precision of the super-resolution reconstruction is confirmed by the calculation of errors from the ideal values. For validation of the super-resolution of spectroscopic data, we applied this method to the analysis of Raman spectra. From 200 Raman spectra of a reference Si substrate with a resolution of about 0.8 cm-1, super-resolution reconstruction with resolution of 0.01 cm-1 was successfully achieved with the promised precision. From the super-resolution spectrum, the Raman scattering peak of the reference Si substrate was estimated as 520.55 (+ 0.12, -0.09) cm-1, which is comparable to the precisely determined value from previous works. The present methodology can be applied to various kinds of spectroscopic analysis, leading to increased precision in the analysis of spectroscopic data and the ability to detect slight differences in spectral peak positions and shapes.