Research on mirror surface shape of space camera fitting based on SVD

2019 ◽  
Author(s):  
Tuo Huang ◽  
Rong-li Chen ◽  
Chang-bo Chu
Keyword(s):  
Surface Shape ◽  
Mirror Surface

Effect of the measuring mirror surface shape error on ruled groove straightness and the grating diffraction wavefront

2020 ◽  
Vol 59 (27) ◽  
pp. 8465
Author(s):  
Xiaotao Mi ◽  
Shanwen Zhang ◽  
Xiangdong Qi ◽  
Haili Yu ◽  
Hongzhu Yu ◽  
...  
Keyword(s):  
Surface Shape ◽  
Shape Error ◽  
Mirror Surface ◽  
Grating Diffraction

Modeling of the Dynamic Surface Profile in Magnetic Fluid Mirrors

2006 ◽  
Author(s):  
Azhar Iqbal ◽  
Foued Ben Amara
Keyword(s):  
Magnetic Field ◽  
Dynamic Response ◽  
Magnetic Fluid ◽  
Retinal Imaging ◽  
Surface Shape ◽  
Effective Control ◽  
Control Input ◽  
Mirror Surface ◽  
Dynamic Surface ◽  
Imaging Application

Magnetic fluid deformable mirrors (MFDMs) present a simple alternative to the expensive and delicate wavefront correctors currently in use in adaptive optics (AO) systems. Such mirrors are particularly suitable for retinal imaging AO systems. The practical implementation of a retinal imaging AO system incorporating a MFDM requires an effective control system to control the shape of the mirror surface. The real-time control of the mirror surface requires a model of the mirror that can be used to determine the dynamic response of the mirror to a magnetic field applied as the control input. This paper presents such a model that not only determines the dynamic response of the MFDM but also takes into account the unique requirements of the retinal imaging application of the mirrors. The mirror is modeled as a horizontal layer of a magnetic fluid. The dynamic response of the mirror to the applied magnetic field is represented by the deflection of the free surface of the layer. The surface deflection is determined by the modal analysis of the coupled fluid-magnetic system. Considering the requirements of the retinal imaging application, the effects of surface tension and depth of the fluid layer are duly represented in the model. The mirror model is described in a state-space form and can be readily used in the design of a controller to regulate the mirror surface shape.

Optical mirror surface shape on-site measurement based on reverse Hartmann test

2021 ◽  
Author(s):  
Bowen Xu ◽  
Shanshan Wang ◽  
Ci Song ◽  
Yinlong Hou ◽  
Feng Shi ◽  
...  
Keyword(s):  
Surface Shape ◽  
Mirror Surface ◽  
Hartmann Test

scholarly journals Design and Optimization for Mounting Primary Mirror with Reduced Sensitivity to Temperature Change in an Aerial Optoelectronic Sensor

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7993
Author(s):  
Meijun Zhang ◽  
Qipeng Lu ◽  
Haonan Tian ◽  
Dejiang Wang ◽  
Cheng Chen ◽  
...  
Keyword(s):  
Surface Shape ◽  
Shape Error ◽  
Temperature Decrease ◽  
Mirror Surface ◽  
Optical Performance ◽  
Uniform Temperature ◽  
Primary Mirror ◽  
Optoelectronic Sensor ◽  
Thermal Adaptability

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.

scholarly journals Research and Experimental Verification on Topology-Optimization Design Method of Space Mirror Based on Additive-Manufacturing Technology

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 354
Author(s):  
Yanchao Fan ◽  
Deyi Dong ◽  
Chao Li ◽  
Yuxin Sun ◽  
Zhiyu Zhang ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Design Method ◽  
Diamond Turning ◽  
Manufacturing Technology ◽  
Surface Shape ◽  
Mirror Surface ◽  
Optical Surface ◽  
Shape Accuracy ◽  
Additive Manufacturing Technology

As one of the most-critical components in space optical cameras, the performance of space mirrors directly affects the imaging quality of space optical cameras, and the lightweight form of mirror blanks is a key factor affecting the structural quality and the surface-shape accuracy of mirrors. For the design requirements of lightweight and high surface-shape accuracy with space mirrors, this study proposes a design and manufacturing method that integrates topology-optimization with additive-manufacturing technology. This article firstly introduced the basic process and key technologies of space-mirror design and analyzed the superiority of combining a topology-optimized configuration design and additive-manufacturing technology; secondly, the topology-optimized design method of a back-open-structure mirror was used to complete the scheme design of a Φ260 mm aperture mirror; finally, the laser selective-melting manufacturing technology was used to complete the Φ260 mm aperture mirror blank. The mirror and its support structure were assembled and tested in a modal mode; the resonant frequencies of the mirror assembly were all over 600 Hz; and the deviation from the analytical results was within 2%. The optical surface of the mirror was turned by the single-point diamond-turning (SPDT) technique. The accuracy of the optical surface was checked by a Zygo interferometer. The RMS accuracy of the mirror surface was 0.041λ (λ is the wavelength; λ = 632 nm). In the test of the influence of gravity on the surface-shape accuracy, the mirror was turned over, which was equivalent to twice the gravity, and the RMS of the mirror surface-shape accuracy was 0.043λ, which met the requirement. The verification results show that the mirror designed and fabricated by the additive-manufacturing-based mirror-topology-optimization method can be prepared by the existing process, and the machinability and mechanical properties can meet the requirements, which provides an effective development method for improving the structural design and optimizing the manufacturing of space reflectors.

scholarly journals X-ray mirror surface figure correction with nanometre precision controlled by layer stresses simulated by FEA

2019 ◽  
Vol 26 (1) ◽  
pp. 234-237 ◽  
Author(s):  
Xianchao Cheng ◽  
Lin Zhang
Keyword(s):  
Thermal Stresses ◽  
Surface Profile ◽  
Second Order ◽  
Surface Shape ◽  
X Rays ◽  
Mirror Surface ◽  
Step Size ◽  
Laser Applications ◽  
Element Analysis ◽  
X Ray

Hard X-rays with energies higher than several kiloelectronvolts can be focused to spot sizes below 10 nm with the present synchrotron beamlines, offering unique advantages for the chemical, elemental and structure analysis of matter. Nevertheless, a surface precision on the nanometre scale for the focusing optics is required and remains the main hurdle limiting X-ray analytical techniques with single-nanometre spatial resolution. On the other hand, to preserve the wavefront properties of coherent X-ray beams, precise control of the reflective mirror surface quality at the nanometre scale is demanded for X-ray free-electron laser applications. In this work, the surface shape of a multilayer-coated X-ray mirror is controlled by layer stresses. The desired surface profile of the mirror is differentiated to its second order to obtain its corresponding curvature profile. With a step size of 1 mm along the mirror length, different coating thicknesses are applied to create different layer thermal stresses from uniform temperature change. The mirror surface profile can be obtained by integrating the curvature profile to its second order and further corrected by moving constant values for the slope and height. The technical process is simulated by finite element analysis (FEA). A case study showed that the residual slope error and the residual height error between the desired shape and the FEA result are 0.22 µrad (r.m.s.) and 1.42 nm (r.m.s.), respectively.

Stability of thermocapillary flows in non-cylindrical liquid bridges

2002 ◽  
Vol 458 ◽  
pp. 35-73 ◽  
Author(s):  
CH. NIENHÜSER ◽  
H. C. KUHLMANN
Keyword(s):  
Reynolds Number ◽  
Prandtl Number ◽  
Critical Reynolds Number ◽  
Volume Fraction ◽  
Thermocapillary Flow ◽  
Surface Shape ◽  
Liquid Bridges ◽  
Gravity Level ◽  
Neutral Curves ◽  
Prandtl Numbers

The thermocapillary flow in liquid bridges is investigated numerically. In the limit of large mean surface tension the free-surface shape is independent of the flow and temperature fields and depends only on the volume of liquid and the hydrostatic pressure difference. When gravity acts parallel to the axis of the liquid bridge the shape is axisymmetric. A differential heating of the bounding circular disks then causes a steady two-dimensional thermocapillary flow which is calculated by a finite-difference method on body-fitted coordinates. The linear-stability problem for the basic flow is solved using azimuthal normal modes computed with the same discretization method. The dependence of the critical Reynolds number on the volume fraction, gravity level, Prandtl number, and aspect ratio is explained by analysing the energy budgets of the neutral modes. For small Prandtl numbers (Pr = 0.02) the critical Reynolds number exhibits a smooth minimum near volume fractions which approximately correspond to the volume of a cylindrical bridge. When the Prandtl number is large (Pr = 4) the intersection of two neutral curves results in a sharp peak of the critical Reynolds number. Since the instabilities for low and high Prandtl numbers are markedly different, the influence of gravity leads to a distinctly different behaviour. While the hydrostatic shape of the bridge is the most important effect of gravity on the critical point for low-Prandtl-number flows, buoyancy is the dominating factor for the stability of the flow in a gravity field when the Prandtl number is high.

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