Diffractive-refractive correction units for plastic compact zoom lenses

Novel figuring method for a multilayer Laue lens

A new, to the best of our knowledge, figuring method for a multilayer Laue lens (MLL) in the hard X-ray region is proposed in this paper. Theoretical simulation at 20 keV shows that the figuring method can compensate for the structure error. The phase errors of the first-order diffracted wave decrease from 0.85π to 0.26π after figuring. The spatial resolution changes from 45 nm to 26 nm after figuring, which is almost the same as that of the ideal MLL with a spatial resolution of 24 nm. The figured MLL can achieve 36% of the ideal MLL's first-order diffraction efficiency. Such method may reduce the requirements for the fabrication of the MLLs, and may make it possible to manufacture the larger numerical aperture MLL with the longer working distance in the future.

Three-dimensional optical coherence digital-null deformography of multi-refractive-surface optics with nanometer sensitivity

Knowledge of the lens deformation during the reliability test is critical for lens design and fabrication. Refractive surface distorts the optical path of probing light, and poses a great challenge to measuring the test-induced nanoscale changes of all refractive lens surfaces simultaneously. In this work, we present an optical coherence digital-null deformography (ODD). A digital null, i.e., the interference signals (including intensity and phase) of the backscattered probing light from each lens surface, was recorded prior to the test with a phase-sensitive optical coherence tomography (OCT). Then the post-test lens was physically aligned to the digital null by actuating a hexapod iteratively with a digital null alignment (DNA) method, so that the refractive distortion was matched. Finally, the changes between the aligned lens and its digital null were measured with an intensity centroid shift (ICS) at micron scale and a joint wavenumber (k)-depth (z) domain phase shift (kz-PhS) at nanoscale. We demonstrate that the proposed kz-PhS has a sensitivity of 4.15 nm and a range of 5 µm without phase wrapping; and the sensitivities of DNA are z translation 0.04 µm, x/y translation 0.24 µm, tilt 0.0003°, and rotation 0.03°. A lens drop test was performed with ODD. Circumventing refractive distortion by the null measurement, ODD can visualize the test-induced changes of all refractive surfaces non-destructively and simultaneously, and it will greatly facilitate lens design and fabrication.

General design formalism for highly efficient flat optics for broadband applications

The use of flat diffractive optical elements (DOEs) for broadband applications, e.g. conventional optical systems, requires DOEs that maintain high efficiencies across the required range of wavelengths, angles of incidence, and grating periods. Here we introduce a general framework for how dispersion engineering can be used to design DOEs that fulfill these requirements and use our approach to determine design rules for broadband DOEs. Our analysis shows that the key to making échelette-type gratings (EGs) suitable for broadband optical systems is the development of new optical materials with specific uncommon dispersion properties. Subsequently, we use our framework to design a representative range of prototype EGs, which allows us to link the specifications of an optical system to the requirements on the EGs' materials. Finally, we show that our design rules apply to all DOEs based on propagation delays including GRIN DOEs and metagratings. Our design rules therefore guide the way towards unlocking the full potential of DOEs for different kinds of broadband applications.

Substrate material selection method for multilayer diffractive optics in a wide environmental temperature range

We present a substrate material selection method for multilayer diffractive optical elements (MLDOEs) to obtain high polychromatic integral diffraction efficiency (PIDE) in a wide environmental temperature range. The extended expressions of the surface relief heights for the MLDOEs are deduced with consideration of the influence of the environmental temperature. The PIDE difference Δη¯(λ) and PIDE change factor F are introduced to select a reasonable substrate material combination. A smaller value of Δη¯(λ) or F indicates a smaller decrease of the PIDE in a wide temperature range, and the corresponding substrate material combination is better. According to the deduced relation, double-layer and three-layer DOEs with different combinations are discussed. The results show that IRG26 and zinc sulfide is the best substrate material combination in the infrared waveband for double-layer DOEs, and polycarbonate is more reasonable than polymethyl methacrylate as the middle filling optical material for three-layer DOEs when the two substrate materials are the same.

Aspherical Lens Design Using Genetic Algorithm for Reducing Aberrations in Multifocal Artificial Intraocular Lens

A complex intraocular lens (IOL) design involving numerous uncertain variables is proposed. We integrated a genetic algorithm (GA) with the commercial optical design software of (CODE V) to design a multifocal IOL for the human eye. We mainly used an aspherical lens in the initial state to the crystalline type; therefore, we used the internal human eye model in the software. The proposed optimized algorithm employs a GA method for optimally simulating the focusing function of the human eye; in this method, the thickness and curvature of the anterior lens and the posterior part of the IOL were varied. A comparison of the proposed GA-designed IOLs and those designed using a CODE V built-in optimal algorithm for 550 degrees myopia and 175 degrees astigmatism conditions of the human eye for pupil size 6 mm showed that the proposed IOL design improved the spot size of root mean square (RMS), tangential coma (TCO) and modulation transfer function (MTF) at a spatial frequency of 30 with a pupil size of 6 mm by approximately 17%, 43% and 35%, respectively. However, the worst performance of spherical aberration (SA) was lower than 46%, because the optical design involves a tradeoff between all aberrations. Compared with the traditional CODE V built-in optimal scheme, the proposed IOL design can efficiently improve the critical parameters, namely TCO, RMS, and MTF.

Design of plastic diffractive-refractive compact zoom lenses for visible-near-IR spectrum

The requirements for selecting the initial scheme for a compact plastic zoom lens are formulated. The main stages of the initial scheme of the transformation, incorporating the diffractive lens and replacement of the lenses' glasses by optical plastics, are presented. The efficiency of the suggested techniques of the optical layout process are demonstrated by using the example of the design and analysis of a zoom lens intended for use in security cameras for day or night vision.

Demonstration of focus-tunable diffractive Moiré-lenses

In an earlier publication [Appl. Opt. 47, 3722 (2008)] we suggested an adaptive optical lens, which consists of two cascaded diffractive optical elements (DOEs). Due to the Moiré-effect the combined optical element acts as a Fresnel zone lens with a refractive power that can be continuously adjusted by a mutual rotation of the two stacked DOEs. Here we present an experimental realization of this concept. Four designs of these Moiré-DOEs (MDOEs) were fabricated in thin (0.7 mm) glass slides by lithography and subsequent etching. Each element was realized as a 16 phase level DOE designed for 633 nm illumination. Our experimental investigation shows that the Moiré-lenses have a broad adjustable refractive power range with a high efficiency, which allows one to use them for flexible beam steering and for imaging applications.