Optical Test System Research Articles

Lightweight structure and unequal length flexible support design of a 1.3×1.2 m rectangular, horizontally supported mirror

A lightweight rectangular mirror designed for a space telescope features a lightweight structure and an innovative unequal length flexible support design. This design incorporates a three-point back support structure, which maintains the surface accuracy of the mirror assembly in a horizontal optical testing layout. The topology optimization design method is applied for the lightweight design of a SiC mirror. According to the principle that optimal gravity surface accuracy of the mirror is achieved when the pivot center of the flexible support coincides with the neutral plane of the mirror, an unequal length flexible support scheme is proposed. Furthermore, a “neck-shrinking” flexible support structure is designed to enhance the comprehensive surface quality of the mirror assembly, achieving better than λ/140 (RMS = 4.5 nm, λ=632.8nm). Following the completion of mirror polishing, an optical test system is established. The test results confirm that the surface shape accuracy satisfies the requirements of the design index. In addition, the mechanical design has been corroborated through dynamic testing.

Chemical etching-assisted femtosecond laser multi-beam rapid preparation of As2Se3 microlens arrays

Chalcogenide glass has gradually evolved into a new generation of infrared optical glasses. As2Se3, a representative chalcogenide glass in the mid-infrared wavelength band, is commonly used in the production of infrared optical devices. In this paper, we primarily used femtosecond laser multi-beam parallel processing technology, complemented by chemical etching technology, to efficiently manufacture infrared microlens arrays with exceptional optical morphology. By adjusting parameters such as the number of laser beam splits, beam spacing, energy, and pulse count, we were able to produce a range of microlens arrays with varying diameters, depths, and filling ratios. Finally, we use the optical imaging test system to focus and capture images of the fabricated microlens arrays, demonstrating excellent optical performance. This processing technology has broad application prospects in the middle infrared band, such as military, medical, and other fields.

Compact near‐eye display for firefighter's self‐contained breathing apparatus

AbstractWe introduce a display for virtual‐reality (VR) fire training. Firefighters prefer to wear and operate a real breathing apparatus while experiencing full visual immersion in a VR fire space. Thus, we used a thin head‐mounted display (HMD) with a light field and folded optical system, aiming to both minimize the volume for integration in front of the face into a breathing apparatus and maintain adequate visibility, including a wide viewing angle and resolution similar to that of commercial displays. We developed the optical system testing modules and prototypes of the integrated breathing apparatus. Through iterative testing, the thickness of the output optical module in front of the eyes was reduced from 50 mm to 60 mm to less than 20 mm while maintaining a viewing angle of 103°. In addition, the resolution and image quality degradation of the light field in the display was mitigated. Hence, we obtained a display with a structure consistent with the needs of firefighters in the field. In future work, we will conduct user evaluation regarding fire scene reproducibility by combining immersive VR fire training and real firefighting equipment.

Adaptive Petal Reflector: In-Lab Software Configurable Optical Testing System Metrology and Modal Wavefront Reconstruction.

This paper addresses two aspects of the metrology of spherical, petal polymer reflectors which are part of an effort by the European Space Agency (ESA) to develop actively controlled foldable reflectors, enabling larger apertures on CubeSats and small satellites. The first problem is that of measuring the surface figure error of the spherical reflector alone during the development phase, and to assess the quality before assembling the telescope (large stroke, low accuracy). The SCOTS (Software Configurable Optical Testing System) appears to provide a fast and satisfactory solution to this problem. The second problem is the wavefront error reconstruction when the petal reflector is mounted on the telescope, because parts of the petals are obscured by the secondary mirror, in such a way that the petals appear completely disconnected, making the gradient-based metrology impossible. Using the fact that the petals have common mechanical boundary conditions at the central support ring, the problem is solved by using a set of orthogonal modes satisfying the same boundary conditions. The vibration modes are used for this purpose; the modal amplitudes are reconstructed from slope data outside the obstruction, allowing for wavefront error reconstruction over the entire surface.

Adaptive modal identification of honeycomb thin-walled composite structures with pit defects under thermal modal testing using variational mode decomposition technique based on digital image correlation

The active imaging blue light high-speed three-dimensional digital image correlation (3D-DIC) system was combined with a transient aerodynamic heating system and random pulse excitation technology to establish a high-frequency thermal vibration optical test system capable of multi-temperature zone testing at 900 °C to accurately obtain the thermal modal parameters of thin-walled structures. The full-field temperature distribution of a novel honeycomb thin-walled composite structure (HTWCS) with pit defects under non-uniform temperature was accurately simulated through reinforcement learning. The first six modal frequencies of honeycomb thin-walled composite structure with pit defects at room temperature increased compared with the non-destructive honeycomb thin-walled composite structure, and the third and fourth modal shapes interchanged. An adaptive modal parameter identification method for full-field three-dimensional vibration measurements under high-temperature environments was developed by combining the successive multivariate variational mode decomposition (VMD) with the modal superposition method. This method can effectively identify close modes. The area ratio-based approach was used to evaluate the damping of the measured response. The finite element model (FEM) of the HTWCS with pit defects at different temperatures was updated using a multi-state step-by-step model updating method and the temperature-dependent material properties were established. The results showed that the introduction of a damping ratio improved the accuracy of the updated FEM of HTWCS with pit defects. The proposed technique is anticipated to provide an effective method for high-frequency thermal vibration optical measurement and modal identification of thin-walled structures under multi-temperature regions.

Preview the Products on Display at Display Week 2023

Preview the Products on Display at Display Week 2023

THEORETICAL RESEARCHES OF THE EMBEDDED FIBER-OPTIC SYSTEM OF TESTING DEFORMATION AND TEMPERATURE OF POLYMER COMPOSITES

This article describes the results of theoretical researches of the system of optical testing of polymer composites by the method of two optical fibers with different sensitivity to deformation and temperature, using integrated arrays of fiber Bragg gratings. The features of the primary data processing from the optical testing system embedded into the composite are considered by the methods of weighted arithmetic mean and approximation by the Gaussian function. The basic relations for calculating the error in determining the temperature and strain with the help of fiber-optic embedded testing systems are obtained. A numerical model of the interrogator has been constructed, which makes it possible to estimate the systematic error of deformation and temperature measurements, including taking into account the noise of a real interrogator. It is shown that, taking into account a number of assumptions for the problem of simultaneous embedded testing of composites with fiber Bragg gratings, it is advisable to apply he method of primary processing of testing data using the approximation of the real spectra of fiber Bragg gratings by the Gaussian function, while in order to increase the reliability of testing, it is necessary to take into account the temperature correction characteristic of a particular interrogating device.

LOCAL ADAPTIVE PHASE CORRECTION ALGORITHM FOR 3D PROFILOMETRY SYSTEMS BASED ON PHASE SHIFTING METHOD

It is very popular to reflect sinusoidal phase patterns to the surface with technique of demodulation of the phase information in order to get 3D surface depth with 2D images.The phase information that extracted with this method is wrapped; so it must be unwrapped.Even though the phase information is unwrapped; there will be some errors because of possibility of non-sinusoidal characteristics of phase patterns, surface discontinuities, low sample ratesand technical handicaps (poor calibration and hardware malfunctions etc).To deal with those errors resulting from the phase unwrapping process, there are some computationally expensive and complex methods have been presented.In this paper, a fast and low complexlocal adaptive phase correction algorithm forfour-step phase shifting methodis implemented especially for oral applications. The method is firstly validated by using synthetic data. After validation process, an optic test system is realized and a few experiments are performed by using real data. For optic system, a look-up table based calibration techniqueis also implemented for getting accurate surface phase information. Visual and quantitative simulation results are presented to show the performance of the method.

Simulation system of lighting environment for optical imaging test

In order to overcome the shortcomings of the solar simulator in the aspect of the performance testing for optical imaging system, a lighting environment simulation system is designed. We select dysprosium lamp, xenon lamp and multiple LEDs as light sources of the solar simulator, and the change of the sun zenith angle is simulated by using the symmetrical method of the light source. Also, the light intensity is controlled by adjusting the output current of the power supply. Lighting environment simulation system not only can simulate spectral irradiance and intensity change of real solar, but also can simulate the real sun depending on the season and the angle of illumination period. This system provided a technical support for the performance testing of optical imaging systems.

High optical response NiO, Pd/NiO and Pd/WO3 hydrogen sensors

In this study, NiO and WO3 oxide semiconductors were fabricated on glass substrates by RF Magnetron Sputtering technique. Structural and optical characterizations of the semiconductors were performed using XRD, SEM, and optical absorption measurements. NiO and WO3 thin films were occasionally coated with palladium. In order to investigate the optical response of these semiconductors under hydrogen gas exposure, an optical gas sensor test system was installed and programmed. In both of the coated and uncoated cases, optical absorption changes due to hydrogen gas exposure on the surface were investigated. It was observed that these changes occur between 450 and 850 nm wave lengths range. The absorption in the NiO semiconductor was reduced between these wave lengths, while the absorption was increased in the WO3 semiconductor. In the uncoated state, only NiO gave an optical response to hydrogen gas. While the palladium coated NiO (Pd/NiO) sensor had the best response and recovery times of respectively 70 s and 206 s for 2% fraction of H2 gas at 300 °C constant temperature, the Pd/WO3 sensor gave the best response time of 340 s. Palladium coating resulted in approximately 150% increase in the responses of the NiO sensors at higher H2 concentration. The lower limit of H2 sensing of the Pd/NiO sensors at 300 °C was at the H2 fraction of 0.05%, while for Pd/WO3 sensors this value was 0.025%.

Distortion analysis and focal length testing of off-axis optical system

Distortion analysis and focal length testing of off-axis optical system

Calibration of single optical wedge compensation test system error by computer generation hologram

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Forced convection method for optical testing system with large aperture and long focal length

Forced convection method for optical testing system with large aperture and long focal length

A Probabilistic Calculation Method of Transformer Temperature Fault Based on Photoelectric Infrared Sensor

Aiming at the defect of the lack of quantitative detection probability evaluation method, we design two models which affect the detection probability of image fusion system. They are spectral contrast modeling of target and background and probability model of transformer fault detection and recognition under the influence of multiple factors. Based on the infrared optical imaging method, we established the fault identification model of multi-mode transformer or its connected parts; Studied several infrared optical imaging fusion test systems, and deduced the calculation method of transformer fault detection based on false alarm probability; Analyzed the correlation between the detection ability of the detection system and the characteristics of the target itself, environmental illumination, detection distance and so on. According to the relationship among SNR, detection range and detection probability, we derived the calculation model of target detection probability of optical imaging system under complex background. Through calculation and experimental analysis, the results show that the proposed method can effectively evaluate the detection probability of photoelectric detection imaging system under different background in practical application.

Study on noise characteristics of 500kV oil-immersed transformer under no-load voltage condition

With the expansion of urban construction scale, substation noise has attracted more and more attention. Noise characteristics and propagation of the oil-immersed transformers are made important theoretical basis of vibration and noise reduction measures. Based on the 500kV oil-immersed transformer, the noise test of transformer structures had been completed. An advanced optical fiber testing system is adopted in the test, which solves the problem of accuracy and reliability in high electromagnetic field and solid-liquid coupling environment. Time domain analysis and frequency analysis for the test data were carried out. By test and analysis, noise characteristics are obtained by the large power transformers. The frequency spectrum of noise and winding vibration in transformer insulation oil is mainly 100Hz and frequency doubling. With the increase of load, the noise presents obvious nonlinear change process.

26.4: A Quantitative Method for L0 Light Leakage Sensitivity of TFT‐LCD Based on JND Energy Ratio

In this paper, a quantitative evaluation method of L0 light leakage sensitivity based on JND energy ratio is established by studying the optical characterization and physical significance of L0 light leakage phenomenon. This method uses continuous quantitative indicators instead of human eye evaluation, which fully improves the accuracy and repeatability, and it can also predict the L0 light leakage level after the test module is assembled into the system set. An optical test system was built to simulate the influence of the system set. The liquid crystal module samples with different glass thickness and different sealant were tested. The test results were consistent with the qualitative judgment results of the human eye after the test module is assembled into tablet PC, and the similar level that the human eye can't be distinguished can be quantitatively distinguished. The repeatability error of the method was only 0.89%.

52‐3: Student Paper: A Quantitative Method for L0‐Leakage Sensitivity in TFT‐LCDs Based on JND Energy Ratio

In this paper, a quantitative evaluation method of L0 light leakage sensitivity based on JND energy ratio is established by studying the optical characterization and physical significance of L0 light leakage phenomenon. This method uses continuous quantitative indicators instead of human eye evaluation, which fully improves the accuracy and repeatability, and it can also predict the L0 light leakage level after the test module is assembled into the system set. An optical test system was built to simulate the influence of the system set. The liquid crystal module samples with different glass thickness and different sealant were tested. The test results were consistent with the qualitative judgment results of the human eye after the test module is assembled into tablet PC, and the similar level that the human eye can't be distinguished can be quantitatively distinguished. The repeatability error of the method was only 0.89%.

Gasochromic properties of thin film oxides in terms of surface physics

A novel gasochromism phenomenon is descried using thin films of the ZnO, NiO and WO3 oxide semiconductors under hydrogen exposition, exhibiting rather advantageous properties than previously used fiber optic coating. The oxides were fabricated on glass substrates by RF Magnetron Sputtering technique. Structural and optical characterizations of the semiconductors were completed with XRD, Raman, SEM and optical absorption measurements. To investigate the optical response of these semiconductors to hydrogen gas, an optical gas sensor test system was prepared and programmed during the studies, using charged coupled device (CCD) signal processing. A nano-layer metal sensitizing of Pd and Pt up to 340% on the thin film surfaces of the various oxide samples of ZnO, NiO and WO3 have also been observed in the range of 450–850 nm wave lengths, covering the VIS-IR range. Overall optical response is rather amphoteric for n and p-type materials, having correlation with the resistivity responses. Present applications of the obtained devices on the hydrogen sensing up to low concentrations of 200 ppm, with relatively low response times around 70 s and that of recovery around 200 s, even at the room temperature execution. It is predicted that this extraordinary situation can also be used for various other applications such as smart windows and solar technology, especially in air and oxygen exposure.

Calibration of single optical wedge test system using computer-generated hologram

Calibration of single optical wedge test system using computer-generated hologram

Platinum activated WO3 optical hydrogen sensors

In this study, WO3 metal oxide structure was investigated as an optical gas sensor. 90 nm WO3 thin films were grown by RF magnetron sputtering on glass substrates. In order to obtain a sensitive layer for H2 gas, 10 nm Pt was coated on the top of WO3 film gas by the same technique. Optical absorbance variations of Pt activated WO3 thin film gas sensor structure (Pt/ WO3) were measured at 40 °C, 75 °C and 125 °C for different Hydrogen concentration level of 1000 ppm − 40.000 ppm. A tungsten halogen lamb and a CCD spectrometer was used at optical gas sensor test system to measure optical absorbance of sensor real-time.