Computational imaging is changing the landscape in many dimensions. If extended depth of focus is leveraged to allow curved image surfaces in the nominal lens design, the lens design environment changes dramatically potentially creating a new class of extreme lens designs.

The lens design problem for the 2014 IODC is to design a 100 mm focal length lens in which all the components of the lens can be manufactured from ten Schott N-BK7 lens blanks 100 mm in diameter x 30 mm thick. The lens is used monochromatically at 587.56 nm. The goal of the problem is to maximize the product of the entrance pupil diameter and the semi-field of view while holding the RMS wavefront error to ≤ 0.070 wave within the field of view. There were 45 entries from 13 different countries. Four different commercial lens design programs were used, along with six custom, in-house programs. The number of lens elements in the entries ranged from 10 to 52. The winning entry from Jon Ehrmann had 25 lens elements, and had an entrance pupil diameter of 33.9 mm and a semi-field of view of 62.5° for a merit function product of 2,119.

For the 3^rd time, the International Optical Design Conference (IODC) included an Illumination Design contest. This year, the contest involved designing the illuminator to project the 1950 Walt Disney “Cinderella” movie using a box of optical knick-knacks. The goal of the problem was to provide the highest screen lumens with greater than 30% uniformity. There were 12 entries from 3 different countries. Three different commercial optical/illumination design packages were used. The winning solution, provided by Alois Herkommer, provided 371 screen lumens.

The WFIRST-AFTA Wide-Field Infrared Survey Telescope TMA optical design provides 0.28-sq°FOV Wide Field Channel at 0.11” pixel scale, operating at wavelengths between 0.76-2.0μm, including a spectrograph mode (1.35-1.95μm.) An Integral Field Channel provides a discrete 3”x3.15” field at 0.15” sampling.

Optical alignment and testing of the Integrated Science Instrument Module of the James Webb Space Telescope is underway. We describe the Optical Telescope Element Simulator used to feed the science instruments with point images of precisely known location and chief ray pointing, at appropriate wavelengths and flux levels, in vacuum and at operating temperature. The simulator's capabilities include a number of devices for in situ monitoring of source flux, wavefront error, pupil illumination, image position and chief ray angle. Taken together, these functions become a fascinating example of how the first order properties and constructs of an optical design (coordinate systems, image surface and pupil location) acquire measurable meaning in a real system. We illustrate these functions with experimental data, and describe the ray tracing system used to provide both pointing control during operation and analysis support subsequently. Prescription management takes the form of optimization and fitting. Our core tools employ a matrix/vector ray tracing model which proves broadly useful in optical engineering problems. We spell out its mathematical basis, and illustrate its use in ray tracing plane mirror systems relevant to optical metrology such as a pentaprism and corner cube.

In recent years, how to eliminate moving elements while realizing optical zoom imaging has been paid much attention. Compared with the conventional optical zooming techniques, removing moving elements would bring in many benefits such as reduction in weight, volume and power cost and so on. The key to implement non-moving-element optical zooming lies in the design of variable curvature mirror (VCM). In order to obtain big enough optical magnification, the VCM should be capable of generating a large variation of saggitus. Hence, the mirror material should not be brittle, in other words the corresponding ultimate strength should be high enough to ensure that mirror surface would not be broken during large curvature variation. Besides that, the material should have a not too big Young’s modulus because in this case less force is required to generate a deformation. Among all available materials, for instance SiC, Zerodur and et.al, CFRP (carbon fiber reinforced polymer) satisfies all these requirements and many related research have proven this. In this paper, a CFRP VCM is designed, fabricated and tested. With a diameter of 100mm, a thickness of 2mm and an initial curvature radius of 1740mm, this component could change its curvature radius from 1705mm to 1760mm, which correspond to a saggitus variation of nearly 23μm. The work reported further proves the suitability of CFRP in constructing variable curvature mirror which could generate a large variation of saggitus.

Super achromatic retarders and polychromatic modulators are required to meet the polarimetry specifications of the Daniel K. Inouye Solar Telescope. These components have been analyzed and toleranced using a birefringent polarization ray trace over wavelength and field of view.

We describe the optical design of a spaceborne f/1.3 catadioptric telescope with a 9 degree field and 77 cm aperture that is being proposed to study objects in the Kuiper belt, Sedna Region, and Oort cloud.

Wide spectral band imaging suggests reflective optics, but achieving a large field-of-view, low f/number, cold-stopped system requires large packaging volumes. Refractive designs are compact but material selection challenging. A design using desirable materials was achieved.

The potpourri of aspherical surfaces offers many possibilities in optical design, even the chance for flexible beam shaping setups. Since these are refractive optical elements the beam shaping is robust with respect to wavelength changes.

A system was designed and built to spatially multiplex four broad area laser diodes (BALD) and condense the light into a multi-mode fiber with a core diameter of 105 um and an NA of 0.15. The lasers were efficiently combined with an étendue aspect ratio scaler (EARS) optic. The EARS works under the principle of a two mirror beam shaper. We were able to successfully couple more than 87% of the optical energy into the fiber. The design of the optical system and the results of several built systems are discussed.

In this work we present the design process as well as experimental results of an optical system for trapping particles in air. For positioning applications of micro-sized objects onto a glass wafer we developed a highly efficient optical tweezer. The focus of this paper is the iterative design process where we combine classical optics design software with a ray optics based force simulation tool. Thus we can find the best compromise which matches the optical systems restrictions with stable trapping conditions. Furthermore we analyze the influence of manufacturing related tolerances and errors in the alignment process of the optical elements on the optical forces. We present the design procedure for the necessary optical elements as well as experimental results for the aligned system.

Multi-FM SSD and CPP was experimentally studied in high fluence and will be equipped on all the beams of SG-III laser facility. The output spectrum of the cascade phase modulators are stable and the residual amplitude modulation is small. FM-to-AM effect caused by free-space propagation after using smoothing by spectral dispersion is theoretically analyzed. Results indicate inserting a dispersion grating in places with larger beam aperture could alleviate the FM-to- AM effect, suggesting minimizing free-space propagation and adopting image relay. Experiments taken on SG-III laser facility indicate when the number of color cycles (Nc) adopts 1, imposing of SSD with 3.3 times diffraction limit (TDL) did not lead to pinhole closure in the spatial filters of the preamplifier and main amplifier with 30-TDL pinhole size. The nonuniformity of the focal spot using Multi-FM SSD and CPP drops to 0.26, comparing to 0.84 only using CPP. The experiments solve some key technical problems using SSD and CPP on SG-III laser facility, and provide a flexible platform for laser-plasma interaction experiments. Combined beam smoothing and polarization smoothing are also analyzed. Simulation results indicate through adjusting dispersion directions of one-dimensional SSD beams in a quad, two-dimensional SSD could be obtained. The near field and far field properties of beams using polarization smoothing were also studied, including birefringent wedge and polarization control plate (PCP). By using PCP, cylindrical vector beams could be obtained. New solutions will be provided to solve the LPI problem encountered in indirect drive laser fusion.

A generalized optimization process for reducing the aberration of a concave grating is developed. Our aberration reduction process is to minimize the root-mean-square spot sizes for the spectral range on the detector plane. To evaluate the performance, a model based on a previous concave grating designed for a mid-infrared (7.5 μm ~13.5 μm) spectrometer is built. The result shows that the current new approach has a dramatic improvement in aberration reduction and yields better spectral resolution.

The Gabor Superlens (GSL) combines light from an array of micro-telescopes to form a single composite image. This is achieved through an initial selection of micro-telescope and array parameters that satisfy a set of first order imaging conditions. Designing a GSL presents two design challenges that are not encountered in conventional (single-aperture) lens design: the array parameters couple design characteristics such as the F/# and field of view to the paraxial design, and the composite image quality can be dominated by aberration of individual elements rather than a summation of aberration contributions throughout the design. This paper begins with an assessment of the highly parameterized design space of the Gabor Superlens to clearly identify relationships between the initial selection of first order design geometry and the consequences they have on system performance. An overview of a streamlined design method follows. Increasingly sophisticated GSL designs are then investigated to demonstrate the effectiveness of using individually corrected lens groups to improve composite image quality.

A compact multi-aperture lens system consists of separate units deployed on a bendable substrate. Each unit includes a fast lens and wobbling sensor which allow high resolution image over a limited field of view.

Tunable GRIN lenses that operate in randomly polarized light may be produced using liquid crystal (LC) materials. We describe one such device and discuss practical methods of evaluating its performance, considering its dependence on polarization.

A light field head-mounted display (LF-HMD) using a micro structure array (MSA, lens array or pinhole array) is proposed to realize true three dimensional (3D) display. Dense light field of 3D scene is generated inside the exit pupil of HMD and the viewer can obtain correct depth. This method not only solves the huge data problem in true 3D displays, but also alleviates the visual fatigue in traditional HMDs. Design considerations of LF-HMD system have been analyzed in detail and an optical see-through LF-HMD has been designed using a wedge-shaped freeform prism cemented with a freeform lens and a pinhole array. The experimental result shows that the proposed method is capable of generating a dense light field to obtain a corrected perception of depth.

We investigate the propagation of a four-dimensional ray grid through freeform optical systems. By analyzing the linear and nonlinear part of this ray-mapping at each surface we can quantify surface aberration contributions within freeform systems.

Since the last IODC meeting, the field of optical design with freeform surfaces has burst onto the scene. This talk will present a first of its kind, all reflective, unobscured, three-mirror 10° full field of view, F/1.9 operational freeform imaging telescope from design to full assembly.

The Monge–Ampère (MA) equation arising in illumination design is highly nonlinear so that the convergence of the MA method is strongly determined by the initial design. We address the initial design of the MA method in this paper with the L² Monge-Kantorovich (LMK) theory, and introduce an efficient approach for finding the optimal mapping of the LMK problem. Three examples, including the beam shaping of collimated beam and point light source, are given to illustrate the potential benefits of the LMK theory in the initial design. The results show the MA method converges more stably and faster with the application of the LMK theory in the initial design.

A new optical imaging design code for NURBS freeform surfaces is described, with reduced optimization cycle times due to its fast raytrace engine, and the ability to handle larger NURBS surfaces because of its improved optimization algorithms. This program, FANO (Fast Accurate NURBS Optimization), is then applied to an f/2 three mirror anastigmat design. Given the same optical design parameters, the optical system with NURBS freeform surfaces has an average r.m.s. spot size of 4 microns. This spot size is six times smaller than the conventional aspheric design, showing that the use of NURBS freeform surfaces can improve the performance of three mirror anastigmats for the next generation of smaller pixel size, larger format detector arrays.

The emergence of freeform surfaces in optical systems creates a need for new design methodologies and tools. We present a new analysis tool to facilitate spectrometer designs that leverage freeform surfaces. We demonstrate this new tool for two common all-spherical spectrometer design forms. Using insights from nodal aberration theory, this novel visualization enables the optical designer to efficiently and effectively implement freeform optical surfaces into spectrometers and other dispersive optical instrumentation.

A large-aperture, wide field-of-view, three-mirror optical system for a space borne astronomical survey telescope has been designed. The unobstructed optical system with a circular pupil has a 2 meter aperture, 1.7 deg² FOV, and provides remarkably good imagery. Freeform surfaces and decentered/tilt surfaces are introduced to the system, which have the advantage of balancing the unsymmetrical aberrations, especially for the wide-field off-axis optical systems. The evaluation of image quality is that the value of the RMS wavefront error is 21 nm, the ellipticity is less than 6.5% in the main imaging area (about 1.1 deg²), and the maximum radius of Encircled Energy 80% (EE80) is less than 0.09arcsec.

Head-worn displays have begun to infiltrate the commercial electronics scene as mobile computing power has decreased in price and increased in availability. When designing informative displays that are head-worn, freeform optical surfaces allow additional enabling degrees of freedom. We present two freeform, all-reflective, two element designs suitable for sunglass mounting.

Laser beam shaping requires controlling the intensity and phase profile of the input laser beam simultaneously. In this paper, a method for designing double freeform surfaces is presented to solve the laser beam shaping problem. Based on Snell’s law and conservation law of energy, a mathematical model is established to convert the double surfaces design problem into an elliptic Monge-Ampère equation with a nonlinear boundary problem by imposing a constraint on the optical path length between the input and output wavefronts. Two different configurations of the beam shaping system are discussed and the good results show clearly the Monge–Ampère equation method provides an effective tool in solving the challenging problem of laser beam shaping.

Known for a long time in non-imaging optics, free form surfaces are progressively used in imaging optics. We will give an overview about several aspects from design and surface description for several state-of-the art systems.

In recent years, freeform surfaces have become increasingly important. This paper introduces new form description and tolerancing additions to ISO 10110 to accommodate freeform surfaces. Information stating how ISO 10110 and related standards documents such as ISO 14999-4 are being continually developed to meet the requirements for specifying freeform surfaces is also provided. The manuscript includes examples illustrating the increased features of the standard.

With the increase in prevalence of LED based solutions and the power of computer optimization, new solutions are being developed for very old problems, such as optimal cove light or wall wash illumination. This paper presents a novel approach to finding a solution to the wall wash problem based on HBLEDs and a single, transmissive optical element to optimize illumination using a segmented conventional optics approach.

We introduce the concept of saddle lenses for the generation of uniform illumination with high efficiency. The design principles and experimental verification of beam shapers incorporating saddle lenses are discussed and demonstrated.

An all-plastic high-performance eyepiece design utilizing a polymer spherical gradient-index optical element is presented. The use of a gradient-index lens in the eyepiece offers better off-axis and chromatic aberration correction, as well as overall performance improvement compared to a similar eyepiece with all homogeneous lenses.

A design study is conducted in the 1-5μm wavelength band for an F/3, 15 degree full field of view, 38mm focal length imaging system. A survey of preferred materials shows the chromatic properties of homogeneous materials in different regions of this spectrum. A survey of GRIN materials, including zinc selenide zinc sulfide GRIN, aluminum oxynitride GRIN, and chalcogenide GRIN, expands the available chromatic properties in this spectral band. Baseline homogeneous triplet designs are explored and compared to previous studies in the literature. The inclusion of a GRIN material in the three element design improves the chromatic correction and results in a system that is nearly diffraction-limited. The three element design is reduced to two elements, where both elements are GRIN, while maintaining comparable performance to the homogeneous triplet.

Gradient-index (GRIN) zoom lenses are shown to offer superior imaging performance to homogenous designs over the visible spectrum. For a given element count, copolymer GRIN designs are better corrected for axial and lateral color than homogeneous aspheric designs.

The design of an F/2 bi-AGRIN Sphero-Chromat is presented, corrected for axial color, spherical aberration and spherochromatism for de-focused wavelength pairs in the visible spectrum. In addition, a bi-AGRIN corrector doublet is designed to work in parallel with the Sphero-Chromat, rendering diffraction limited polychromatic performance between 0.44 and 1.0 μm.

We demonstrate a searchlight based on a high brightness LED source. On the basis of conservation laws, an optical design is developed that concentrates the light of the source into a small cone.

A hollow backlight unit (HBLU) preserves all the benefits of a conventional backlight unit based on a solid light guide but has a lower weight and cost. We study the performance of a unique HBLU architecture vs. various parameters of the backlight assembly.

This paper describes the optical and illumination design of a CPV solar energy system. The challenges of creating a highly efficient yet low-cost system architecture come from many sources, but are primarily limited by the photoelectron conversion efficiency of the cells and the illumination performance of the system for on-axis and off-axis pointing scenarios. Furthermore, the need for high solar spectral throughput, evenly concentrated sunlight, and tolerance to offaxis pointing places strict illumination requirements on the optical design. To be commercially viable, the cost associated with all components must be minimized so that when taken together, the absolute installed cost of the system in kWh is lower than any other solar energy method. We present two low-cost optical design embodiments of a dishbased concentration photovoltaic (CPV) system that utilize Köhler illumination to achieve good illumination uniformity across an array of solar cells. Further optimization for active shadowing compensation and compound electrical I-V curve modeling for the solar cell array is performed that allows realistic off-axis performance scenarios to be modeled with the correct power response sensitivity.

Laser activated remote phosphor (LARP) is an upcoming technology for high luminance SSL light engines. This presentation outlines some of the challenges met reducing the engine’s size, so it can be retrofitted into DLP-projectors.

Optical films with microstructures can achieve uniform illuminance on the target and glare control with no registration to LEDs. An engineered optical film design with microstructures on both sides is demonstrated. A spacing ratio of 1.64 is obtained compared to 1.28 with just LEDs while there is less light at higher angles for better glare ratings.

Conventional concentrating photovoltaic (CPV) systems track the sun with high precision dual-axis trackers. The emergent field of tracking-integrated optics has the potential to simplify the mechanics of CPV systems by loosening or eliminating the need for dual-axis tracking. In a tracking-integrated scheme, external module tracking is complemented or entirely replaced by miniature tracking within the module. This internal tracking-integration may take the form of active small-motion translation, rotation of arrayed optics, or by passive material property changes induced by the concentrated light. These methods are briefly reviewed. An insolation weighting model is presented which will aid in the design of tracking-integrated optics by quantifying the tradeoff between angular operation range and annual sunlight collection. We demonstrate that when tracking-integrated optics are used to complement external module tracking about a horizontal, North-South oriented axis, truncating the operational range may be advantageous. At Tucson AZ latitude (32.2°N), 15.6% of the angular range may be truncated while only sacrificing 3.6% of the annual insolation. We show that modules tracked about a polar-aligned axis are poorly-suited for truncation.

Line-focus parabolic trough mirrors for solar thermal generation cannot produce the high concentration required for concentrating photovoltaic (CPV) systems. We describe a freeform lens array with toroidal symmetry which intercepts the low-concentration line focus to produce a series of elongated, high-concentration foci. The design employs 2D Kӧhler illumination to improve the acceptance angle in one direction. The two-stage concentrator has 1000X average geometric concentration with an acceptance angle of +/-1.49° in the azimuthal direction and +/-0.29° in the elevation direction. Preliminary results of a prototype roll-forming process are shown in thermoplastics and B270 glass.

Standards provide a conduit for understanding and communication in the global optics industry. Proper use and knowledge of standards is beneficial to global commerce and increases productivity. In this paper the design utility and efficiency afforded by standards is shown with examples that are congruent with current ANSI and ISO published documents.

One of the key challenges confronting optical engineers is efficient design form comparison, specifically evaluating cost-effective manufacturability. Traditional methods involve aberration balancing and assessing ray bending to determine the most relaxed design form. Such methods can be effective for experts. However, they only indirectly assess cost, are difficult to explain to non-optical engineers, do not directly relate to tolerances, and do not make any connection to the inherent challenges of holding a set of tolerances. The most desirable means of assessing manufacturability, especially during the early design phase should be efficient, simple to use and understand, and provide capability to directly assess error impact and relative cost. There are a number of ways to approach this challenge. Quite notably, this paper shows that a tolerance grade mapping system is particularly useful due to the balance it brings between its ease of use, flexibility, and detailed relation to cost. Two lens design examples are included that illustrate the method and its ease of use.

We investigate ray trace simulations of isotropic and anisotropic diffusers. Such diffusers require large data sets of highly accurate BSDF measurements that cover the range of illumination angles incident on the diffuser in the simulation.

Passive athermalization requires that the materials (both optical and mechanical) and optical powers be carefully selected in order for the image to stay adequately in focus at the plane of the detector as the various materials change in physical dimension and refractive index. For a large operational temperature range, the accuracy of the thermo-optical coefficients (dn/dT coefficients and the Coefficients of Thermal Expansion) can limit the performance of the final system. Based on an example lens designed to be passively athermalized over a 200°C temperature range, and using a Monte Carlo analysis technique, we examine the accuracy to which the expansion coefficients and dn/dT coefficients of the system must be known.

We will present a design approach for a surgical light consisting of a central high-power LED module and a metal-free TIR reflector. The reflector’s surface is designed as a grooved surface providing two TIR reflections.

We present a 3-path optical system for studying the retinal movement of jumping spiders: a visible OLED virtual reality system presents stimulus, while NIR illumination and imaging systems observe retinal movement.

A scatterfield microscope for deep sub-wavelength semiconductor metrology using 193 nm light has been designed. In addition to accommodating the fixed numerical aperture and size of its commercial catadioptric objective lens, the illumination optics are formed to implement essential parameters necessary for angular illumination control at the sample plane. This angle-resolved scatterfield microscope requires access to a relatively large (> 10 mm) conjugate back focal plane as well as increased fluence from the ArF excimer laser source. The parametric optimization process yielded a telecentric conjugate back focal plane with appropriate numerical aperture and diameter by adjustment of the parameters of two interrelated lens groups.

Broadband high-resolution micro-objectives for optical biopsy imaging applications benefit from radial gradient-index lenses, improving performance and potentially decreasing manufacturing sensitivity. Achromatization is achieved with fewer elements as gradient-index lenses can replace homogeneous doublets or triplets.

The five year survival rate for ovarian cancer is over 90% if early detection occurs, yet no effective early screening method exists. We have designed and are constructing a dual modality Optical Coherence Tomography (OCT) and Multispectral Fluorescence Imaging (MFI) endoscope to optically screen the Fallopian tube and ovary for early stage cancer. The endoscope reaches the ovary via the natural pathway of the vagina, cervix, uterus and Fallopian tube. In order to navigate the Fallopian tube the endoscope must have an outer diameter of 600 μm, be highly flexible, steerable, tracking and nonperforating. The imaging systems consists of six optical subsystems, two from OCT and four from MFI. The optical subsystems have independent and interrelated design criteria. The endoscope will be tested on realistic tissue models and ex vivo tissue to prove feasibility of future human trials. Ultimately the project aims to provide women the first effective ovarian cancer screening technique.

Illumination has been a critical factor to producing good imaging in microlithography since the beginning. Early lithographers used very simple illumination schemes, but as they improved their understanding of how the illumination influences image fidelity and resolution they moved into more complex partially coherent illumination conditions. Today, lithographers deploy many tricks with coherence and polarization that are tightly coupled with the patterns being imaged to help achieve seemingly impossible resolutions well below the classical definition. In this talk we review the progress of illumination engineering in microlithography up to the present.

A tool is developed with the macro capability of CODE V for optical design with off-the-shelf catalog lenses, which can greatly reduce the fabrication costs for an optical system and shorten its development cycle. This tool automatically replaces current elements in the system by stock lenses in the database, and gets the system optimized at the same time. Major aspects of the tool, including the preparation of the stock lens database, the optimization strategy and the replacement method are discussed in detail. Three examples are designed to demonstrate the effectiveness of the replacement tool, and the results show that acceptable performance can be achieved by this tool. Finally, limitations and applications of this tool are discussed. Our tool can effectively replace elements in a system with stock lenses, and it can also improve optical performance of a system already composed of stock lenses by further replacing and optimization.

Time and costs for manufacturing prototypes can be signficantly decreased by using stock lenses. An f –Ѳ lens design based on our approach and a comparison to the Zemax stock lens matching tool are presented. The designed lens is used for a high power laser cleaning application, and the requirements of this application are discussed in detail.

High performance, compact cinematography lenses working over a large sensor area are demanding designs which are achieved using one or two high departure aspheric elements. With sag departures from best fit sphere of up to a few millimeters, the use of such aspheres is accompanied by a number of consequences. These include high cost metrology, very tight opto-mechanical tolerances and the potential for image artifacts produced during the sub-aperture grinding and polishing process. A modified asphere manufacturing process was utilized to reduce artifacts by eliminating the subaperture grinding and pre-polishing. This method is limited to aspheric surfaces which can be directly polished from a spherical base surface with aspheric departures of <15μm. These very low departure aspheres have the benefit of inexpensive metrology and tolerance relaxation compared with high departure aspheres. Interferograms, slope maps, and out-of-focus images demonstrate the feasibility and advantages of direct asphere generation from a polished sphere. A series of large format lenses covering focal lengths from telephoto to wide angle, were redesigned to determine the feasibility of the use of very low departure aspheres. Increasing the number of aspheric surfaces but reducing the aspheric departure to less than 15μm was demonstrated. We conclude that 3-5 very low departure aspheres are sufficient to provide similar performance to the high departure asphere designs for most focal lengths. One limitation encountered was in the wide angle lenses. The exception was the wide angle lenses where it is difficult to reduce departures below 30μm while maintaining the same optical performance.

Ray tracing methods for correcting chromatic aberration of imaging system are described. Monochromatic and chromatic aberration correction is separated into two independent problems. A similar method is applied to athermalize an optical system.

Simulated results demonstrate the impact of detector noise on the design of a broadband wavefront coded optical system. We conclude that noise must be included as a first-order design constraint in cubic phase-encoded systems.

Camera modules in mobile devices have become ubiquitous, and the optical design and fabrication technology behind them is underappreciated. We will present a basic summary of the technology and discuss some recent developments that may influence future camera designs.

We present two miniature all plastic megapixel panomorph lenses for consumer electronics (total track length (TTL) of 6.56 mm) and mobile devices (TTL of 3.80 mm) showing the unique challenges from specification, design, manufacturing and testing phases of these new generation of miniature 180° FoV wide-angle lenses.

Folded zoom lenses offer an interesting opportunity for a review of patent literature: they are of a reasonable complexity that the designs are likely to be instructive, they offer a small range of design constraints because of the standardization of CMOS imager sizes and the mechanical constraints imposed on DSC cameras, and there is enough recent activity in awarded patents that a representative sample of contemporary designs can be collected. This paper presents a review of recent patent literature for folded zoom lenses. Zemax models were built for the designs disclosed in 67 patents. For this large set of models, the distribution of paraxial properties and lens materials is presented. For the most-common design constraints, two particularly-similar disclosed designs are compared in detail. Engineering differences between the two disclosed designs are compared to differences in patent claims directed to the disclosed designs; the patents’ claims are shown to omit, at least for these two patents, some design differences that seem important from an engineering point of view.

Three different approaches to calculation of internal structure of bokeh image in camera lenses with two aspheric surfaces are analyzed and compared – the transfer function approach, the beam propagation approach and direct raytracing in an optical design software. The transfer function approach is the fastest and provides accurate results when peak-to-valley of mid-spatial frequency phase modulation induced at the lens exit pupil is below λ/10. Aspheric surfaces are shown to contribute to the bokeh structure differently increasing the complexity of bokeh image especially for offaxis bokeh.

Designers of advanced digital imaging systems are frequently challenged with considering not only the optics and sensor, but also the effects of image processing in the selection of the best architecture to meet their system objectives. Leveraging the image processing degree of freedom presents a considerable opportunity if one incorporates system-level metrics in the design and optimization process. Including the image processing degree of freedom also significantly expands the set of solutions and enables different trades of performance, cost, size, weight, and power. Here, we demonstrate the opportunity available to the system designer by exploring the design of a wide angle system intended to maximize a system-level human visual performance metric. The resulting system solutions span a range of optical, optomechanical, and signal processing complexity and show systems with a wide range of size and cost.

An overview of color correction strategies is presented. Starting with basic first-order aberration theory, we identify known color corrected solutions for doublets and triplets. Reviewing the modern approaches of Robb-Mercado, Rayces-Aguilar, and C. de Albuquerque et al, we find that they confirm the existence of glass combinations for doublets and triplets that yield color corrected solutions that we already know exist. Finally we explore the use of the y, ӯ diagram in conjunction with aberration theory to identify the solution space of glasses capable of leading to color corrected solutions in arbitrary optical systems.

Methods are presented of using skew rays to optimize a generally astigmatic optical system to obtain the desired Gaussian beam focus and minimize aberrations, and to calculate the propagating generally astigmatic Gaussian beam parameters at any point. The optimization method requires very little computation beyond that of a conventional ray optimization, and requires no explicit calculation of the properties of the propagating Gaussian beam. Unlike previous methods, the calculation of beam parameters does not require matrix calculations or the introduction of non-physical concepts such as imaginary rays.

We present an image restoration technique, combination of optical technologies and digital image processing technologies. Especially, we show the image restoration technique for images influenced by lens aberration, diffraction, sampling process and many filters.

Decomposed into Gauβlets (Gaussian beamlets or “fat rays”), a diffracting wavefield can be propagated through an optical system by simple ray tracing. As an update to a 1990 ILDC presentation, the method’s progress since then is covered along with new comparisons against more precise solutions.

When new three-dimensional packages are developed for imaging optical systems, the rotational symmetry of the optical system is often broken, changing its imaging behavior and making the optical performance worse. A method to restore the performance is to use freeform optical surfaces that compensate directly the aberrations introduced from tilting and decentering the optical surfaces. In order to effectively optimize the shape of a freeform surface to restore optical functionality, it is helpful to understand the aberration effect the surface may induce. Using nodal aberration theory the aberration fields induced by a freeform surface in an optical system are explored. These theoretical predications are experimentally validated with the design and implementation of an aberration generating telescope.

This work describes a design process which greatly increases the depth of field of a simple three-element lens system intended for biometric iris recognition. The system is optimized to produce a point spread function which is insensitive to defocus, so that recorded images may be deconvolved without knowledge of the exact object distance. This is essentially a variation on the technique of wavefront encoding, however the desired encoding effect is achieved by aberrations intrinsic to the lens system itself, without the need for a pupil phase mask.

The skew aberration is a form of polarization aberration causes a rotation of polarization states across the pupil. Skew aberration is intrinsic to the optical system depending on the ray path only and whose magnitude is independent of the coatings or other polarization effects. Skew aberration has a much greater effects in high numerical aperture optical systems. A critical angle corner cube system is analyzed as an example to review the skew aberration’s effects.

Secondary color strongly depends on appropriate glass choice during optical design. The specific impact of individual lenses to the overall correction can be revealed by a lens-resolved analysis of secondary color. In this paper, thick-lens contributions to secondary axial and lateral color are presented, utilizing a suitable definition for secondary color when residual primary color is present. Several design examples illustrate the systematic impact of glass choice on the overall color correction.

The method of Grey’s orthonormal optimization is reviewed. Aspects of the method that contributed to its success are reviewed, and factors limiting its application are discussed. Current status of the method is summarized.

In several of the standard derivations of first-order optics, the actual approximations used are unclear or overstated. Some derivations are also incomplete. Several of the fundamental derivations of paraxial and Gaussian optics have been reformulated to provide a clearer explanation and better understanding of the key concepts of basic image formation for our students. The paraxial refraction raytrace equation, the power of a general Gaussian system and the relationship between the numerical aperture and the F-number are examined. The paraxial refraction equation is shown to be a bridge between paraxial optics and Gaussian optics that defines the power of an optical system.

The 2013 China lens design competition was to design a conjugate zoom lens with maximum magnification ratio, numerical aperture and field of view, and with specified image quality and distortion. The lens is used at visible spectrum range from 486nm to 656 nm. The goal of the problem is to maximize the product of the semi-image height, objective numerical aperture of configuration 1, image numerical aperture of configuration 2 and the magnification ratio of two configurations while holding the distortion to within ±1% and the RMS wavefront error to ≤ 0.1 wavelength within the field of view. Over 20 entries were received and the results were analyzed.

This paper provides an overview of field curvature aberration correction. It is known that for sharp imaging on a flat surface the Petzval sum must be zero or nearly so. However, current lenses for mobile phones depart from this principle to some extent. We provide an insightful discussion about some mechanisms for the correction of field curvature aberration.

Methods for thermal modeling, analysis and optimization are presented. Modeling distinguishes between three basic types of lens mounts. For analysis also FEA-results are incorporated in the optical model. Optimization with a simple, glass substitution method and a paraxial method is presented.

The interactions between errors in manufacturing are examined for ten double Gauss lens specifications drawn from U.S. patents. The particular focus is on center thickness and radius tolerances of doublet lenses in these specifications and on the possibility of specifying these tolerances jointly. A procedure for rapid identification of lenses whose performance would be improved by joint tolerance specification is described. Then benefits of specifying thickness and radius tolerances of doublet lenses jointly are demonstrated using Monte Carlo analysis.

Decentration of a lens within an optical system can be used to redirect the path of the axial principal ray, shifting the entire image. This will introduce ‘decentred aberrations’ into the system. This paper will investigate the decentred aberrations of an image intensified system, which uses a decentred lens to achieve image shift to correct boresight errors at assembly. The analysis will be conducted using a decentred aberration theory developed at Canon. This system will be compared to a patent lens with image stabilising capability. It will be shown that an acceptable level of lens shuffle insensitivity can still be achieved in a relatively simple design form. The decentred aberration theory will then be used to suggest alternative design forms.

The tolerancing of lens systems has become more complex as system performance requirements tighten. The tolerancing of just the center thicknesses, surface radii, and surface irregularity are no longer sufficient for optical elements. This paper focuses on a new method to tolerance optical surfaces. There have been many papers written about different methods to tolerance optical surfaces which look to limit the artifacts left by different fabrication processes. The method proposed in this paper focuses on tolerancing to meet system performance, not the fight against the surface fingerprint of a particular fabrication process.

Constraining the Seidel aberrations of optical surfaces is a common technique for relaxing tolerance sensitivities in the optimization process. We offer an observation that a lens’s Abbe number tolerance is directly related to the magnitude by which its longitudinal and transverse color are permitted to vary in production. Based on this observation, we propose a computationally efficient and easy-to-use merit function constraint for relaxing dispersion tolerance sensitivity. Using the relationship between an element’s chromatic aberration and dispersion sensitivity, we derive a fundamental limit for lens scale and power that is capable of achieving high production yield for a given performance specification, which provides insight on the point at which lens splitting or melt fitting becomes necessary. The theory is validated by comparing its predictions to a formal tolerance analysis of a Cooke Triplet, and then applied to the design of a 1.5x visible linescan lens to illustrate optimization for reduced dispersion sensitivity. A selection of lenses in high volume production is then used to corroborate the proposed method of dispersion tolerance allocation.

Image degradation due to scattered radiation from residual optical fabrication errors is a serious problem in many short wavelength (X-ray/EUV) imaging systems. Most commercially-available image analysis codes (ZEMAX, Code V, ASAP, FRED, etc.) currently require the scatter behavior (BSDF data) to be provided as input in order to calculate the image quality of such systems. This BSDF data is difficult to measure and rarely available for the operational wavelengths of interest. Since the smooth-surface approximation is often not satisfied at these short wavelengths, the classical Rayleigh-Rice expression that indicates the BRDF is directly proportional to the surface PSD cannot be used to calculate BRDFs from surface metrology data for even slightly rough surfaces. However, an FFTLog numerical Hankel transform algorithm enables the practical use of the computationally intensive Generalized Harvey-Shack (GHS) surface scatter theory [1] to calculate BRDFs from surface PSDs for increasingly short wavelengths that violate the smooth surface approximation implicit in the Rayleigh-Rice surface scatter theory [2-3]. The recent numerical validation [4] of the GHS theory (a generalized linear systems formulation of surface scatter theory), and an analysis of image degradation due to surface scatter in the presence of aberrations [5] has provided credence to the development of a systems engineering analysis of image quality as degraded not only by diffraction effects and geometrical aberrations, but to scattering effects due to residual optical fabrication errors as well. These advances, combined with the continuing increase in computer speed, leave us poised to fully integrate optical metrology and fabrication into the optical design process.