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The weight of the primary mirror increases as the aperture of ground-based telescopes increases, making it more challenging to maintain the positional stability and surface accuracy of the solid primary mirror. Consequently, a 2 m lightweight silicon carbide (SiC) mirror and an optimization method were proposed in this study. The relationship between the gravitational deformation of the mirror and its thickness and number of supports was derived based on force analysis of the mirror; the thickness of the mirror and the appropriate number of supports were obtained as initial parameters for optimization. The back structure of the mirror was designed in a lotus pattern to improve its rigidity. Numerous structural parameters were classified into major and non-major parameters based on the results of a sensitivity analysis. The non-major and major structural parameters were optimized using a Latin hypercube design method and a non-dominated sorting genetic algorithm, respectively. The optimized 2 m lightweight SiC mirror had a mass of 119 kg and an areal density of 38.7 kg/m2. The surface figure error root-mean-square (RMS) in the vertical state of the optical axis and the first modal resonance of the mirror assembly calculated using finite element analysis were 11.3 nm and 76.5 Hz, respectively. Modal tests of the mirror assembly were conducted using the hammering method, achieving a maximum relative frequency error of 7.4% compared with the simulation results. The optimized 2 m SiC mirror was over 50% lighter than traditional passive Zerodur mirrors of the same size. [ABSTRACT FROM AUTHOR]

The weight of the primary mirror increases as the aperture of ground-based telescopes increases, making it more challenging to maintain the positional stability and surface accuracy of the solid primary mirror. Consequently, a 2 m lightweight silicon carbide (SiC) mirror and an optimization method were proposed in this study. The relationship between the gravitational deformation of the mirror and its thickness and number of supports was derived based on force analysis of the mirror; the thickness of the mirror and the appropriate number of supports were obtained as initial parameters for optimization. The back structure of the mirror was designed in a lotus pattern to improve its rigidity. Numerous structural parameters were classified into major and non-major parameters based on the results of a sensitivity analysis. The non-major and major structural parameters were optimized using a Latin hypercube design method and a non-dominated sorting genetic algorithm, respectively. The optimized 2 m lightweight SiC mirror had a mass of 119 kg and an areal density of 38.7 kg/m2. The surface figure error root-mean-square (RMS) in the vertical state of the optical axis and the first modal resonance of the mirror assembly calculated using finite element analysis were 11.3 nm and 76.5 Hz, respectively. Modal tests of the mirror assembly were conducted using the hammering method, achieving a maximum relative frequency error of 7.4% compared with the simulation results. The optimized 2 m SiC mirror was over 50% lighter than traditional passive Zerodur mirrors of the same size.

The thermostressed state of one of the proposed telescope designs was analyzed by means of a finite element model using the ANSYS software package. It is shown that under normal thermal conditions, small temperature variations (within ±1°C) do not cause telescope malfunction. The range of possible temperature changes that result in the maximum permissible focus shifts and tilts of the axis of the secondary mirror relative to the primary mirror was determined. [ABSTRACT FROM AUTHOR]

In a Cassegrain optical system, the surface precision of the primary mirror is an important factor in the quality of the image. The design of a lightweight primary mirror with a high-quality optical surface is crucial. In this thesis, an integrated mirror light engine design optimization process is proposed for an aviation optoelectronic device. It is based on the Kriging surrogate model and nests the topology optimization algorithm, which constructs the mirror RMS value response surface and obtains the dominant relationship between mirror structure and surface accuracy. The optimal surface figure lightweight structure of the mirror is obtained by optimizing the surrogate model with an additive criterion and multi-objective optimization analysis. The root mean square value (RMS) of the corresponding primary mirror is 10.41 nm, which is better than 1/40 λ (λ = 632.8 nm). This meets the optical design specifications. The optimal primary mirror structure is analyzed by using the finite element method, which verifies the precision of the Kriging surrogate model. It has an error of 0.28%. The kinetic analysis of the primary mirror shows that the primary mirror does not yield to plastic deformation or even failure under a three-way 20 g acceleration load. This meets the environmental suitability requirements. [ABSTRACT FROM AUTHOR]

Lightweight, high stability, and high-temperature adaptability are the primary considerations when designing the primary mirror of a micro/nano satellite remote sensing camera. In this paper, the optimized design and experimental verification of the large-aperture primary mirror of the space camera with a diameter of Φ610 mm is carried out. First, the design performance index of the primary mirror was determined according to the coaxial tri-reflective optical imaging system. Then, SiC, with excellent comprehensive performance, was selected as the primary mirror material. The initial structural parameters of the primary mirror were obtained using the traditional empirical design method. Due to the improvement of SiC material casting complex structure reflector technology level, the initial structure of the primary mirror was improved by integrating the flange with the primary mirror body design. The support force acts directly on the flange, changing the transmission path of the traditional back plate support force, and has the advantage that the primary mirror surface shape accuracy can be maintained for a long time when subjected to shock, vibration, and temperature changes. Then, a parametric optimization algorithm based on the mathematical method of compromise programming was used to optimize the design of the initial structural parameters of the improved primary mirror and the flexible hinge, and finite element simulation was conducted on the optimally designed primary mirror assembly. Simulation results show that the root mean square (RMS) surface error is less than λ/50 (λ = 632.8 nm) under gravity, 4 °C temperature rise, and 0.01 mm assembly error. The mass of the primary mirror is 8.66 kg. The maximum displacement of the primary mirror assembly is less than 10 μm, and the maximum inclination angle is less than 5″. The fundamental frequency is 203.74 Hz. Finally, after the primary mirror assembly was precision manufactured and assembled, the surface shape accuracy of the primary mirror was tested by ZYGO interferometer, and the test value was 0.02 λ. The vibration test of the primary mirror assembly was conducted at a fundamental frequency of 208.25 Hz. This simulation and experimental results show that the optimized design of the primary mirror assembly meets the design requirements of the space camera. [ABSTRACT FROM AUTHOR]

In a Cassegrain optical system, the surface precision of the primary mirror is an important factor in the quality of the image. The design of a lightweight primary mirror with a high-quality optical surface is crucial. In this thesis, an integrated mirror light engine design optimization process is proposed for an aviation optoelectronic device. It is based on the Kriging surrogate model and nests the topology optimization algorithm, which constructs the mirror RMS value response surface and obtains the dominant relationship between mirror structure and surface accuracy. The optimal surface figure lightweight structure of the mirror is obtained by optimizing the surrogate model with an additive criterion and multi-objective optimization analysis. The root mean square value (RMS) of the corresponding primary mirror is 10.41 nm, which is better than 1/40 λ (λ = 632.8 nm). This meets the optical design specifications. The optimal primary mirror structure is analyzed by using the finite element method, which verifies the precision of the Kriging surrogate model. It has an error of 0.28%. The kinetic analysis of the primary mirror shows that the primary mirror does not yield to plastic deformation or even failure under a three-way 20 g acceleration load. This meets the environmental suitability requirements.

Lightweight, high stability, and high-temperature adaptability are the primary considerations when designing the primary mirror of a micro/nano satellite remote sensing camera. In this paper, the optimized design and experimental verification of the large-aperture primary mirror of the space camera with a diameter of Φ610 mm is carried out. First, the design performance index of the primary mirror was determined according to the coaxial tri-reflective optical imaging system. Then, SiC, with excellent comprehensive performance, was selected as the primary mirror material. The initial structural parameters of the primary mirror were obtained using the traditional empirical design method. Due to the improvement of SiC material casting complex structure reflector technology level, the initial structure of the primary mirror was improved by integrating the flange with the primary mirror body design. The support force acts directly on the flange, changing the transmission path of the traditional back plate support force, and has the advantage that the primary mirror surface shape accuracy can be maintained for a long time when subjected to shock, vibration, and temperature changes. Then, a parametric optimization algorithm based on the mathematical method of compromise programming was used to optimize the design of the initial structural parameters of the improved primary mirror and the flexible hinge, and finite element simulation was conducted on the optimally designed primary mirror assembly. Simulation results show that the root mean square (RMS) surface error is less than λ/50 (λ = 632.8 nm) under gravity, 4 °C temperature rise, and 0.01 mm assembly error. The mass of the primary mirror is 8.66 kg. The maximum displacement of the primary mirror assembly is less than 10 μm, and the maximum inclination angle is less than 5″. The fundamental frequency is 203.74 Hz. Finally, after the primary mirror assembly was precision manufactured and assembled, the surface shape accuracy of the primary mirror was tested by ZYGO interferometer, and the test value was 0.02 λ. The vibration test of the primary mirror assembly was conducted at a fundamental frequency of 208.25 Hz. This simulation and experimental results show that the optimized design of the primary mirror assembly meets the design requirements of the space camera.

The design of a very high-resolution Korsch-based optical satellite telescope with a ground sampling distance of 25 cm through employing a primary mirror with a diameter of 1.4 m is investigated previously in Part I, and the system performance is evaluated in Part II. In this Part III, the telescope size reduction using the deployable synthetic primary mirror approach is presented. Since the largest telescope element, the primary mirror size reduction is useful for decreasing the telescope volume and mass. Consequently, the reduction in satellite development cost and relaxing the selection of the launch vehicle are attained. Three configurations of segmented sparse apertures are conceptually examined, including rectangular, trapezoidal, and hexagonal patterns. The performance of each configuration with a different number of segments is evaluated. Through the tradeoff criterion, the optimal number of segments is investigated. The assessment parameters adopted in the study involve the number of segments, modulation transfer function, stowed volume, and segment width. The results show that without a significant loss in optical performance, a volume reduction of about 70% is accomplished. [ABSTRACT FROM AUTHOR]

For balloon-borne telescopes, the primary mirror is the most important optical element, but designing a primary mirror with an excellent overall performance is a challenge. To comprehensively consider the contradictory objectives of the root mean square (RMS) surface error under gravity in the X and Z directions, the mass and fundamental frequency of the primary mirror, a parametric primary mirror design using the compromise programming method based on topology optimization is proposed. The parametric design of the compromise programming method based on topology optimization is used to find the optimal solution for X-direction RMS (RMSx), Z-direction RMS (RMSz), mass, and fundamental frequency. Compared with the initial primary mirror structure designed according to traditional experience, the overall performance is improved. Results show that the respective mass of the primary mirror, the RMSx and the RMSz decreased by 8.5%, 14.3% and 10.5% compared to those before optimization. Comprehensive consideration can prove the effectiveness of parametric design based on the topology optimization of the primary mirror. This method provides a reference for the design of other primary mirrors for balloon-borne telescope and space cameras. [ABSTRACT FROM AUTHOR]

This article discusses the connection between the compulsive use of toxic substances and the shortcomings of the family environment. It provides a detailed account of the author's experience with an adult patient in a psychoanalytically oriented mental health care institution in France and argues that drug abuse can be conceived as a self‐calming strategy and an effort to be without the other. The coexistence of neurotic and psychotic mechanisms in the patient's mental function is highlighted and discussed in the light of structural psychopathology. Finally, French institutional psychotherapy, as a dynamic and tolerant form of psychiatry that emphasizes multi‐transference in response to the split‐off elements of the psychotic ego, highlights the pertinence of treating psychotic drug addiction in a pluralistic framework. [ABSTRACT FROM AUTHOR]

In order to improve the image quality of the aerial optoelectronic sensor over a wide range of temperature changes, high thermal adaptability of the primary mirror as the critical components is considered. Integrated optomechanical analysis and optimization for mounting primary mirrors are carried out. The mirror surface shape error caused by uniform temperature decrease was treated as the objective function, and the fundamental frequency of the mirror assembly and the surface shape error caused by gravity parallel or vertical to the optical axis are taken as the constraints. A detailed size optimization is conducted to optimize its dimension parameters. Sensitivities of the optical system performance with respect to the size parameters are further evaluated. The configuration of the primary mirror and the flexure are obtained. The simulated optimization results show that the size parameters differently affect the optical performance and which factors are the key. The mirror surface shape error under 30 °C uniform temperature decrease effectively decreased from 26.5 nm to 11.6 nm, despite the weight of the primary mirror assembly increases by 0.3 kg. Compared to the initial design, the value of the system’s modulation transfer function (0° field angle) is improved from 0.15 to 0.21. Namely, the optical performance of the camera under thermal load has been enhanced and thermal adaptability of the primary mirror has been obviously reinforced after optimization. Based on the optimized results, a prototype of the primary mirror assembly is manufactured and assembled. A ground thermal test was conducted to verify difference in imaging quality at room and low temperature, respectively. The image quality of the camera meets the requirements of the index despite degrading.

For balloon-borne telescopes, the primary mirror is the most important optical element, but designing a primary mirror with an excellent overall performance is a challenge. To comprehensively consider the contradictory objectives of the root mean square (RMS) surface error under gravity in the X and Z directions, the mass and fundamental frequency of the primary mirror, a parametric primary mirror design using the compromise programming method based on topology optimization is proposed. The parametric design of the compromise programming method based on topology optimization is used to find the optimal solution for X-direction RMS (RMSx), Z-direction RMS (RMSz), mass, and fundamental frequency. Compared with the initial primary mirror structure designed according to traditional experience, the overall performance is improved. Results show that the respective mass of the primary mirror, the RMSx and the RMSz decreased by 8.5%, 14.3% and 10.5% compared to those before optimization. Comprehensive consideration can prove the effectiveness of parametric design based on the topology optimization of the primary mirror. This method provides a reference for the design of other primary mirrors for balloon-borne telescope and space cameras.