Annular Force Based on Variable Curvature Mirror Technique

Xiao-peng, 解晓蓬 Xie; Hui, 赵惠 Zhao; Chuang, 李创 Li; Xuewu, 樊学武 Fan; Guo-rui, 任国瑞 Ren; Wen-yi, 柴文义 Chai; Liang, 徐亮 Xu; Yu, 苏宇 Su

doi:10.3788/gzxb20164508.0822001

Cited by 5 publications

(3 citation statements)

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“…As Fig. 2 tells, Former Soviet Union [18][19][20], France [21][22][23], Germany [24,25], America [26][27][28], Japan [29,30] and China [10,31,32] have done lots of research on VCM for different application purposes and we also make our own contributions to this field as well [12][13][14][15][16]. Among these versatile applications, focus adjusting and zooming are two basic ones.…”

Section: Re-focusmentioning

confidence: 99%

“…At present, the mirrors of the optical camera are rigid and the parameters are fixed. According to our researches [12][13][14][15][16], if the secondary mirror is changed into a variable curvature mirror whose curvature radius can be controlled as required, the focal plane could be quickly adjusted in a very precise way. However, image quality assessment is needed to provide a cue to refocus and the calculation is also time consuming.…”

Section: Introductionmentioning

confidence: 99%

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Depth of focus extension of space-borne optical camera through variable curvature mirror

Zhao,

Xie,

Yang

et al. 2023

Optical Design and Testing XIII

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Currently, most space-borne optical cameras have fixed focal length and depth of focus. In this case, the range within which the target can be clearly imaged has been pre-determined before launch. However, the distance of the target to the optical camera might be unknown or change very fast and therefore focus adjustment has to be carried out to obtain clear images. However, no matter which refocusing technique is used, focus adjustment might lag behind the object distance variation and depth of focus extension is a better way. Wave-front coding can be used to extend the depth of focus of incoherent imaging system but the surface profile of the phase mask could not be changed dynamically, which is not flexible for application. In this manuscript, by combing the variable curvature mirror (VCM) and coded imaging technique together, a new depth of focus extension technique is proposed. According to our previous studies, the focal plane could be quickly adjusted by changing the curvature radius of VCM. Compared with the curvature variation speed, the exposure time of the camera is quite long. Therefore, by adjusting the focal plane very fast in a wide range during the exposure through VCM, an equivalent coded optical transfer function having no null frequency points within bandwidth is generated and the image captured is uniformly blurred. After that, with the help of digital restoration, the clear image could be obtained. Because the focal plane could be adjusted through variable curvature mirror in the range of millimeter, the proposed method could be used to obtain clear images with greatly extended depth of focus.

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Section: Re-focusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Depth of focus extension of space-borne optical camera through variable curvature mirror

Zhao,

Xie,

Yang

et al. 2023

Optical Design and Testing XIII

View full text Add to dashboard Cite

show abstract

“…European Southern observatory have employed variable curvature reflectors to expand the field of view of optical interferometers, utilizing pressure differentials in enclosed chambers to control the optical quality of these surfaces [22]. Moreover, an annular force-based variable focus mirror has been introduced based on elasticity theory, demonstrating its ability to achieve minute variations in aperture [23]. Tunable reflectors are also extensively employed with solid-state lasers to actively correct thermal lensing errors [24].…”

Section: Introductionmentioning

confidence: 99%

An electromechanically driven dielectric elastomer based tunable reflector

Kashyap,

Agrawal,

Kumar

et al. 2024

Smart Mater. Struct.

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Deformable optics offer numerous advantages over conventional optical assemblies, including compactness, cost-effectiveness, efficiency, and flexibility. This study focuses on a reflector based on Dielectric Elastomer Actuators (DEAs) with an internal fluid (air) coupling. DEAs are a class of electroactive materials adept at accommodating substantial actuation strains and rapid responses. Fluid distributed between the active and passive parts remains entirely enclosed by the device and transmits actuation pneumatically. Dynamic maneuvers conducted through a series of controlled electrical signals demonstrate proper control over optical characteristics. However, DEs exhibit inherent flaws in dynamic actuation, referred to as instabilities, which are mitigated by applying an initial pre-stretch. The study identifies optimal parameters that confer stability to the reflector: minimum to no creep, zero residual vibrations, and low viscous losses. An analytical framework is developed to assess device performance, focusing on the spherical curvature assumption that closely resembles the behavior of tunable spherical reflectors. Additionally, an optical bench setup is employed to demonstrate the relationship between focal length and applied pressure. Notably, this paper underscores the potential of a DE-based variable focal length reflector to function effectively within a dynamic environment.

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Elastic bending of variable curvature mirrors: validation of a simplified analytical method

Xie

Hugot

et al. 2019

Appl. Opt.

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This work explores the variable curvature mirror's (VCM) elastic bending rules through modeling it as a thin elastic plate with an exponential thickness distribution actuated with a uniform pressure under simply supported boundary conditions. By using the smallparameter method, the general analytical expression of a plate's deflection is worked out. The results calculated by the analytical solution are compared to the finite element analysis of a VCM model with the same specific parameters. We demonstrate that the two have a good correlation with the one the other. This analytical solution is an effective way to predict a VCM's deflection.

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Annular Force Based on Variable Curvature Mirror Technique

Cited by 5 publications

References 0 publications

Depth of focus extension of space-borne optical camera through variable curvature mirror

Depth of focus extension of space-borne optical camera through variable curvature mirror

An electromechanically driven dielectric elastomer based tunable reflector

Elastic bending of variable curvature mirrors: validation of a simplified analytical method

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