Direct design approach to calculate a two-surface lens with an entrance pupil for application in wide field-of-view imaging

Nie, Yunfeng; Duerr, Fabian; Thienpont, Hugo

doi:10.1117/1.oe.54.1.015102

Cited by 12 publications

(6 citation statements)

References 25 publications

(37 reference statements)

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“…While manufacturability has often constrained optical elements to have rotational invariance, the emerging field of freeform optics leverages more complex curvatures to enable novel functionalities and simplified compound optical systems 1 – 4 . These elements have been shown to be capable of correcting aberrations 3 , off-axis imaging 4 , expanding field of view 5 , and increasing depth of field 6 . Recent interest in freeform optics has been driven by potential applications in near-eye displays 7 , 8 as well as compact optical systems for medical, aerospace, and mobile devices where there are stringent constraints on the size and weight of the optical package 9 .…”

Section: Introductionmentioning

confidence: 99%

Metasurface Freeform Nanophotonics

Zhan

Colburn

Dodson

et al. 2017

Sci Rep

104

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Freeform optics aims to expand the toolkit of optical elements by allowing for more complex phase geometries beyond rotational symmetry. Complex, asymmetric curvatures are employed to enhance the performance of optical components while minimizing their size. Unfortunately, these high curvatures and complex forms are often difficult to manufacture with current technologies, especially at the micron scale. Metasurfaces are planar sub-wavelength structures that can control the phase, amplitude, and polarization of incident light, and can thereby mimic complex geometric curvatures on a flat, wavelength-scale thick surface. We present a methodology for designing analogues of freeform optics using a silicon nitride based metasurface platform for operation at visible wavelengths. We demonstrate a cubic phase plate with a point spread function exhibiting enhanced depth of field over 300 micron along the optical axis with potential for performing metasurface-based white light imaging, and an Alvarez lens with a tunable focal length range of over 2.5 mm corresponding to a change in optical power of ~1600 diopters with 100 micron of total mechanical displacement. The adaptation of freeform optics to a sub-wavelength metasurface platform allows for further miniaturization of optical components and offers a scalable route toward implementing near-arbitrary geometric curvatures in nanophotonics.

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Section: Introductionmentioning

confidence: 99%

Metasurface Freeform Nanophotonics

Zhan

Colburn

Dodson

et al. 2017

Sci Rep

104

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“…Originally, the multi-fields direct design method was proposed for two on-axis refractive freeform surfaces in imaging lens design with an incorporated entrance pupil 20,21 . In this work, it is further extended to solve a tailored imaging problem for off-axis mirror system.…”

Section: Multi-fields Design Methods To Calculate Two Off-axis Mirrorsmentioning

confidence: 99%

Optical design of an ultrashort throw ratio projector with two freeform mirrors

et al. 2016

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In this work, an optical design approach is presented to design an ultrashort throw distance projection system by combination of an off-the-shelf refractive lens and two off-axis freeform mirrors. These two freeform mirrors are used to greatly shorten the projection distance by more than three times compared to conventional (rotationally symmetric) systems, while still maintaining a good imaging quality.Firstly, a direct design method that enables the simultaneous calculation of two off-axis freeform-profile mirrors by partially coupling more than three fields is introduced. The specifications of the conventional refractive lens are taken into account during this procedure. The pupil matching principle is applied to ensure good performance between the two sub-systems. The calculated mirrors then serve as a good starting point for optimization using commercial optical design software. To step from freeform profiles to freeform surfaces, the calculated two profiles are fitted into odd polynomials to evaluate the image quality and then re-fitted into XY polynomials for further optimization. Finally, the polynomial coefficients of the two freeform mirrors are imported into the optical design program. The merit function is built from RMS spot radii over the full field, and additional constraints are made for correcting distortion. After optimization, the calculated initial design quickly converges to a well performing imaging system.As an example, an ultrashort throw distance projection lens with a large 80-inch diagonal image at 400mm throw distance is designed, analyzed and compared with literature data. The values of MTF are over 0.6 at 0.5 lp/mm and the distortion is less than 1.5%: showing a very good and well balanced imaging performance over the entire field of view.

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“…Thanks to our Deep Proton Writing [4] and Ultraprecision Diamond Tooling technologies, we can process optical components to feature extreme optical quality finish, high-aspect ratio structures and absolute freeform shapes [5,6]. Next to their obvious use non-imaging applications, we have recently shown that freeform optics also hold great potential for imaging applications [7,8]. For sub-micrometer features, we make use of 3D direct laser writing, based on two-photon photopolymerization using femtosecond laser pulses [9].…”

Section: Introductionmentioning

confidence: 97%