Optical analysis of miniature lenses with curved imaging surfaces

Reshidko, Dmitry; Sasián, José M.

doi:10.1364/ao.54.00e216

Cited by 37 publications

(16 citation statements)

References 15 publications

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“…Extending lens design optimization to include an arbitrarily curved sensor broadens the set of high quality lens designs. Several recent papers have explored the potentially dramatic performance improvements possible with curved sensor surfaces [1][2][3][4][5][6] including improvements such as 7x reductions in length, 37x in weight, and significantly better modulation transfer function (MTF) and relative illumination, especially at the edges of the image field; the benefits and simplicity of this are evidenced in the human eye [ Fig. 1(A)].…”

Section: Introductionmentioning

confidence: 99%

Highly curved image sensors: a practical approach for improved optical performance

et al. 2017

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Abstract:The significant optical and size benefits of using a curved focal surface for imaging systems have been well studied yet never brought to market for lack of a high-quality, massproducible, curved image sensor. In this work we demonstrate that commercial silicon CMOS image sensors can be thinned and formed into accurate, highly curved optical surfaces with undiminished functionality. Our key development is a pneumatic forming process that avoids rigid mechanical constraints and suppresses wrinkling instabilities. A combination of formingmold design, pressure membrane elastic properties, and controlled friction forces enables us to gradually contact the die at the corners and smoothly press the sensor into a spherical shape. Allowing the die to slide into the concave target shape enables a threefold increase in the spherical curvature over prior approaches having mechanical constraints that resist deformation, and create a high-stress, stretch-dominated state. Our process creates a bridge between the high precision and low-cost but planar CMOS process, and ideal non-planar component shapes such as spherical imagers for improved optical systems. We demonstrate these curved sensors in prototype cameras with custom lenses, measuring exceptional resolution of 3220 line-widths per picture height at an aperture of f/1.2 and nearly 100% relative illumination across the field. Though we use a 1/2.3" format image sensor in this report, we also show this process is generally compatible with many state of the art imaging sensor formats. By example, we report photogrammetry test data for an APS-C sized silicon die formed to a 30° subtended spherical angle. These gains in sharpness and relative illumination enable a new generation of ultra-high performance, manufacturable, digital imaging systems for scientific, industrial, and artistic use. References and links 1.S.B.Rim, P.B. Catrysse, R. Dinyari, K. Huang, P. Peumans, The optical advantages of curved focal plane arrays, Optics Express, 16 (7), 4965-4971 (2008 TRANSDUCERS 2015TRANSDUCERS , 7181365, 2073TRANSDUCERS -2076TRANSDUCERS (2015.

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Section: Introductionmentioning

confidence: 99%

Highly curved image sensors: a practical approach for improved optical performance

et al. 2017

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“…The LSF and the 1-D MTF are again calculated following Eqs. (1) and (2). For the calculation of the diffraction MTF, n rays is chosen so that a further increase in the number of rays no longer causes any changes in the resulting MTF.…”

Section: Calculation Of the Mtfmentioning

confidence: 99%

Effects of misalignments on the modulation transfer function measurement of camera lenses analyzed in optomechanical simulations

et al. 2020

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of misalignments on the modulation transfer function measurement of camera lenses analyzed in optomechanical simulations," Opt. Eng. 59(3), 034101 (2020), Abstract. The Physikalisch-Technische Bundesanstalt has developed a reference setup for measuring the modulation transfer function (MTF) of camera lenses with the goal of reaching an expanded measurement uncertainty of 0.01 (coverage probability of 95%) for various measurement configurations. We present optomechanical simulations of the setup behavior, which are used to investigate the influence of the combined mechanical misalignments on the MTF depending on the lens under test. The investigations are carried out as part of Monte Carlo studies for different sample lenses and field heights considering the correlations between the effects of different positioning errors on the MTF measured. The results of the sensitivity analyses have allowed appropriate alignment strategies to be identified that significantly reduce the uncertainty contribution of the positioning errors. By implementing these strategies, the target measurement uncertainty can be achieved for most of the desired measurement configurations. In addition, the comparison of three different sample lenses shows that the MTF sensitivity to misalignments strongly depends on the characteristics of the lens to be measured. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.Recent developments in the use of camera lenses-e.g., in smartphones, professional cine cameras, or cameras used in advanced driver-assistance systems-necessitate high-precision quality control procedures to ensure high performance, cost-effective production, and compliance with safety aspects. 1-3 Since the theory of optical transfer function was described and the first measuring devices were developed in the 1950s, 4-7 specifying the imaging performance of optical components by a modulation transfer function (MTF) became a widely used technique in optical design and quality testing. Although the MTF is commonly used to specify the quality of imaging systems, at present, there is a lack of services offering traceable MTF calibrations.Motivated by the increasing demand in the industry, the Physikalisch-Technische Bundesanstalt (PTB), in cooperation with an industrial partner, is developing an MTF reference setup for camera lenses with the aim of reaching an expanded measurement uncertainty of 0.01 (coverage probability of 95%) for various measurement configurations. The aims of the project are that an accredited laboratory for MTF calibrations of camera lenses is established and the traceability will be supported by this reference setup. 8 According to our knowledge, there is currently no commercial MTF measurement setup available offering the desired accuracy for different field heights (on-axis and off-axis).

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“…The aspheric optical elements located close to the image plane contribute higher-order field curvature and astigmatism. Different orders of the field curvature and astigmatism are balanced to compensate for any residual Petzval curvature [19].…”

Section: Mobile Phone Camera Lensmentioning

confidence: 99%

The role of aberrations in the relative illumination of a lens system

Reshidko

Sasián

2016

SPIE Proceedings

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Several factors impact the light irradiance and relative illumination produced by a lens system at its image plane. In addition to the cosine-fourth-power radiometric law, image and pupil aberrations, and light vignetting also count. In this paper, we use an irradiance transport equation to derive a closed form solution that provides insight into how individual aberration terms affect the light irradiance and relative illumination. The theoretical results are in agreement with real ray tracing.

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Optical analysis of miniature lenses with curved imaging surfaces

Cited by 37 publications

References 15 publications

Highly curved image sensors: a practical approach for improved optical performance

Highly curved image sensors: a practical approach for improved optical performance

Effects of misalignments on the modulation transfer function measurement of camera lenses analyzed in optomechanical simulations

The role of aberrations in the relative illumination of a lens system

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