Flexible focus variable expander

Lü, Xiaoyuan; Zhang, Yaoning; Cheng, Zheng

doi:10.1117/12.317918

Cited by 4 publications

(1 citation statement)

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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%

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%

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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Low-loss tunable beam collimator and expander assembly with no moving parts using an engineered diffuser and varifocal lenses

Syed

Imeri

2023

J. Opt. Soc. Am. A

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In this paper, we present a novel design for a tunable beam collimator. A variable collimator assists in achieving an adaptive size of an output collimated beam. Alternatively, it can also provide an adjustable output beam divergence angle for a noncollimated beam output. Tunable collimators are highly desirable for various applications in testing, engineering, and measurements. Such devices are also useful in providing tunable illumination of samples or targets in microscopes and emulating different target distances for characterizing the performance of camera systems in laboratory settings. The proposed collimator has two distinct advantages: it is light-efficient compared with pinhole-based collimator designs, and it delivers a large range of output beam sizes without involving the mechanical motion of bulk components. These attributes are achieved via the use of an engineered diffuser (in the place of a pinhole) and a pair of large aperture tunable focus lenses, which deliver a tunable magnification to the output collimated beam. In laboratory experiments, we achieve an optical transmission efficiency of 90% for the proposed tunable collimator.

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Solving, analyzing, manufacturing, and experimental testing of thickness distribution for a cycloid-like variable curvature mirror

Xie

Wang

et al. 2021

Opt. Express

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A cycloid-like variable curvature mirror (VCM) for zoom-imaging systems was investigated. An analytical-deformation solution to a thin-elastic plate with a cycloid-like thickness distribution and simply supported boundary condition under uniform pressure was found using a small parameter method. The finite-element analysis of the thin-elastic plate and designed VCM showed a good correlation with the analytical solution. The VCM was manufactured and polished to the initial shape with a root mean square (RMS) of 1/80λ. Finally, with air-pressure-based actuation testing under 0.07 MPa, the VCM deforms approximately 36.89 µm and maintains the RMS surface performance of 1/10λ, 1/40λ with and without spherical aberrations, respectively.

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Flexible focus variable expander

Cited by 4 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

Low-loss tunable beam collimator and expander assembly with no moving parts using an engineered diffuser and varifocal lenses

Solving, analyzing, manufacturing, and experimental testing of thickness distribution for a cycloid-like variable curvature mirror

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