Design of athermalized mounting structure for the sub-aperture primary mirror of a synthetic aperture telescope

The imaging quality of the synthetic aperture system is sensitive to the positioning accuracy of the sub-aperture primary mirror. A novel flexible mounting structure of bimetallic material is proposed for the athermalization of the sub-aperture primary mirror of the Fizeau Synthetic Aperture Telescope – which is composed of seven sub-aperture. The axial position accuracy of the sub-aperture primary mirror must be less than 5 µm under 10°C temperature rise to meet the requirements of the optical system. Firstly, a single mounting unit is analyzed theoretically, and the initial parameters are determined. The conceptual design of the mounting structure is carried out by using initial parameters. The orthogonal optimization algorithm and range analysis are used to optimize the structural parameters. The finite element model of the flexible mounting structure is established and the coupled thermal-mechanical simulation analysis is performed. Then the thermal sensitivity test of the sub-aperture primary mirror mounting structure was carried out. Under the effect of a temperature rise of 10°C, the axial displacement of the sub-aperture primary mirror mounting surface is less than 3 µm. Finally, the synthetic aperture system is assembled, and the optical test verifies that the synthetic aperture system has good imaging capabilities.

Modernization of NASA Johnson Space Center’s Chamber A to support Cryogenic Vacuum Optical Testing of the James Webb Space Telescope (JWST)

NASA is the mission lead for the James Webb Space Telescope (JWST), the next of the “Great Observatories,” scheduled for launch in 2021. NASA is directly responsible for the integration and test (I&T) program that culminated in an end-to-end cryo vacuum optical test of the flight telescope and instrument module in Chamber A at NASA Johnson Space Center. Historic Chamber A is the largest thermal vacuum chamber at Johnson Space Center and one of the largest space simulation chambers in the world. Chamber A has undergone a major modernization effort to support the deep cryogenic, vacuum and cleanliness requirements for testing the JWST. This paper describes the upgrades to the Chamber A facility: Thermal Shrouds, Helium Refrigeration, Liquid Nitrogen System, High Vacuum System, Clean Airflow System, and Utilities.

In vivo label-free observation of tumor-related blood vessels in small animals using a newly designed photoacoustic 3D imaging system

Introduction: Photoacoustic technology can be used for non-invasive imaging of blood vessels. In this paper, we report on our prototype photoacoustic imaging system with a newly designed ultrasound sensor and its visualization performance of microvascular in animal. Methods: We fabricated an experimental system for animals using a high-frequency sensor. The system has two modes: still image mode by wide scanning and moving image mode by small rotation of sensor array. Optical test target, euthanized mice and rats, and live mice were used as objects. Results: The results of optical test target showed that the spatial resolution was about 2 times higher than that of our conventional prototype. The image performance in vivo was evaluated in euthanized healthy mice and rats, allowing visualization of detailed blood vessels in the liver and kidneys. In tumor-bearing mice, different results of vascular induction were shown depending on the type of tumor and the method of transplantation. By utilizing the video imaging function, we were able to observe the movement of blood vessels around the tumor. Conclusion: We have demonstrated the feasibility of the system as a less invasive animal experimental device, as it can acquire vascular images in animals in a non-contrast and non-invasive manner.

Neutron optical test of completeness of quantum root-mean-square errors

While in classical mechanics the mean error of a measurement is solely caused by the measuring process (or device), in quantum mechanics the operator-based nature of quantum measurements has to be considered in the error measure as well. One of the major problems in quantum physics has been to generalize the classical root-mean-square error to quantum measurements to obtain an error measure satisfying both soundness (to vanish for any accurate measurements) and completeness (to vanish only for accurate measurements). A noise-operator-based error measure has been commonly used for this purpose, but it has turned out incomplete. Recently, Ozawa proposed an improved definition for a noise-operator-based error measure to be both sound and complete. Here, we present a neutron optical demonstration for the completeness of the improved error measure for both projective (or sharp) as well as generalized (or unsharp) measurements.

Study of CuS Thin Films Deposited by PLD Simulated for Prism Based SPR Sensor

Copper Sulfide CuS thin film was prepared using pulsed laser deposition PLD technique and characterized by X-ray and SEM. The optical, structural, and morphological properties are examined at different energies 500 mJ, 600 mJ, 700 mJ, and 800 mJ. The best result was 600 mJ which annealed at various annealing temperatures 300°C, 350°C, 400°C, and 450°C. The effect of thermal annealing on CuS thin film was examined X-ray and SEM. CuS Film was simulated using a prism-based SPR optical sensor. This paper introduces the optical test study of CuS thin film deposited by pulsed laser deposition technique on the quartz substrate and supported by theoretical application study under the effect of surface plasmon resonance (SPR). In this research field, the optical and morphological characteristics of the CuS thin film were deposited by PLD at different laser energies. The annealing process was applied for better-deposited thin-film; the XRD results, SEM images, transmittance T%, and energy gap Eg were analyzed thoroughly and compared to evaluate the thin-film. This effort was made in an in-depth analysis of CuS thin film deposited by PLD on the quartz substrate and applied theoretically in surface plasmon application.

Visualization of an internal sand displacement field around a laterally loaded vertical pile

In this research, an internal sand displacement field around a laterally loaded vertical pile is visualized using transparent soil and an image processing technique called digital image cross-correlation (DIC). DIC is a region-based image processing technique which can calculate the displacement field between two images. Transparent soil is made of silica gel with a pore fluid having the same refractive index. Transparent soil has been studied to have the strength and deformation properties similar to natural soil. An optical test set-up is developed to capture the images during loading. This optical test set-up consists of a camera, a laser light, a line generator lens, a loading frame, a Plexiglas mould, and a PC. The saturated fine sand in loose condition is modeled in this research. A laser light sheet is generated to slice the transparent soil model by passing a laser beam through the line generator lens. A distinctive laser speckle pattern is generated through the interaction between the laser light and transparent soil. A series of images are taken from the camera while a scaled pile is being loaded laterally. The displacement fields are calculated by cross-correlating two consecutive images and the corresponding strain fields are deduced from the displacement fields. The development of both displacement and strain fields is investigated by studying deformation and strains at different loading stages. The test results are similar to the published data. This research improves the understanding of soil movement around a laterally loaded pile. It also advances the physical modeling technique using transparent soil.

Visualization of an internal sand displacement field around a laterally loaded vertical pile

In this research, an internal sand displacement field around a laterally loaded vertical pile is visualized using transparent soil and an image processing technique called digital image cross-correlation (DIC). DIC is a region-based image processing technique which can calculate the displacement field between two images. Transparent soil is made of silica gel with a pore fluid having the same refractive index. Transparent soil has been studied to have the strength and deformation properties similar to natural soil. An optical test set-up is developed to capture the images during loading. This optical test set-up consists of a camera, a laser light, a line generator lens, a loading frame, a Plexiglas mould, and a PC. The saturated fine sand in loose condition is modeled in this research. A laser light sheet is generated to slice the transparent soil model by passing a laser beam through the line generator lens. A distinctive laser speckle pattern is generated through the interaction between the laser light and transparent soil. A series of images are taken from the camera while a scaled pile is being loaded laterally. The displacement fields are calculated by cross-correlating two consecutive images and the corresponding strain fields are deduced from the displacement fields. The development of both displacement and strain fields is investigated by studying deformation and strains at different loading stages. The test results are similar to the published data. This research improves the understanding of soil movement around a laterally loaded pile. It also advances the physical modeling technique using transparent soil.

A method for tire wet grip performance evaluation based on grounding characteristics

The wet grip performance of tire is one of the important performances affecting vehicle safety. The steering, acceleration, and braking of the vehicle are directly affected by the grounding characteristics between the radial tire and the ground. In order to study the influence of grounding characteristics of the tire on wet grip performance, ten 205/55R16 tires produced by different manufacturers were selected and tested. The grounding characteristics of the tires were tested using an optical test rig for tire grounding pressure distribution, considering inflation pressure distribution, load and wheel alignment. The tire-road contact area was subdivided into five parts, and 69 parameters were used to describe the grounding characteristics. A software was proposed to process the test results automatically, and 69 grounding characteristic parameters of each tire were obtained. Correlation analysis on tire wet grip performance and grounding characteristics was used for selecting the principal parameters. Finally, eight grounding characteristic parameters related to tire wet grip performance was obtained. Among them are five grounding characteristic parameters (central area rectangle ratio, central area width, internal shoulder length-to-width ratio, external and internal shoulder contact area ratio, external and internal shoulder impression area ratio) which have high correlation to tire wet grip performance, and three grounding characteristic parameters (external shoulder width, external shoulder length-to-width ratio, external and internal shoulder width ratio) which have low correlation to the wet grip performance of the tire. The principal component analysis method was used to analyze the highly correlated grounding characteristic parameters, and the regression equation for evaluating tire wet grip performance was fitted. The comparison of experimental and fitted values show that the errors are within 4%. The result demonstrates that, the method for evaluating wet grip performance of the radial tire through tire-road grounding characteristics was achieved.