Commercial Optical Design Software Research Articles

Automatic Method of Exploring the Landscape of Freeform Dioptric Optical Problems, Working in the Infrared Region

We present an automated method of finding different freeform dioptric starting systems, working in the infrared region, for further optimization in commercial optical design software. Our developed method couples the simultaneous multiple surface (SMS) method, introduced by Benítez and Miñano, with automatic optimization in Zemax OpticStudio. The method allows an optical designer to explore the merit function (MF) landscape of freeform optical problems. In this article, we apply our method to a size, weight, and power (SWaP) problem, and we compare our designed system with a system found in the literature that has the same aperture of F/1.2. Then, we increase the aperture of the system up to F/0.9, taking advantage of the use of freeform surfaces.

High precision ray tracing method for space camera in optical design

Ray tracing plays a key role in lens design area, and it is an important tool to study the problems in physics like optics. Nowadays, ray tracing becomes ubiquitous and is widely used in optical automatic design, such as aberration analysis, optimization, and tolerance calculation. With the impulse of application requirements, optical systems like space camera develop towards large scale, high degree of accuracy and complication. The magnitude of aberrations increases exponentially with the growth of focal length and aperture, even a minor perturbation error can result in severe degeneration of image quality. As a consequence, the stringent requirements for precision, accuracy and stability of ray tracing turn higher. Reliable commercial software, for example, America’s Zemax, has high precision in ray tracing, because of commercial purpose, the process of ray tracing is a black box. It is now more important to understand what error factors are formed for ray tracing, and how these running errors can be reduced effectively. In this paper, from floating point arithmetic perspective, an error model for ray tracing is provided. This error model is suitable for not only meridional rays, but also skew rays. Starting from IEEE Standard for Binary Floating-Point Arithmetic, presentation error and rounding error are analyzed, followed by the computation process of ray’s intersection point with a quadratic surface, then rounding error expression for the intersection point is presented. In addition, error expression for distance along the ray from the reference surface to the next surface is also induced. These two error expressions are called error model, and it clearly indicates that spatial coordinates on the reference surface, direction vector and distance between the two adjacent surfaces are the main error sources. Based on the error model, some of effective measures, for instance, reprojection, spatial transformation, and direction vector’s normalization are taken to reduce the rounding error. Moreover, in the process of solving quadratic equation, conjugate number method is utilized in order to avoid increasing substantially in relative error called catastrophic cancellation. Numerical experiments and classical optical design for space camera are also given. From numerical computing view, two precision tests based on Multiple Precision Floating-Point Reliable (MPFR) library are introduced to verify our method mathematically. The experimental results show that our algorithm has the same precision (14 significant digits) as MPFR, while the existing method fails to pass tests, and has only 8 significant digits at most. Moreover, both the Cassegrain space camera and off-axis three-mirror-anastigmat space camera are used to illustrate our method’s accuracy. Experimental results indicate that our method has higher precision, more than 5 to 6 orders of magnitudes than the existing method. In addition, our algorithm has higher precision than the commercial optical design software Zemax, and residuals are 3 orders of magnitudes on average less than Zemax.

Optical Quality Variation of Different Intraocular Lens Designs in a Model Eye: Lens Placed Correctly and in an Upside-Down Position

Introduction: Intraocular lenses (IOLs) may lose their optical quality if they are not correctly placed inside the capsular bag once implanted. One possible malpositioning of the IOL could be the implantation in an upside-down position. In this work, three aspheric IOLs with different spherical aberration (SA) have been designed and numerically tested to analyse the optical quality variation with the IOL flip, and misalignments, using a theoretical model eye. Methods: Using the commercial optical design software OSLO, the effect of decentration and tilt was evaluated by numerical ray tracing in two conditions: in their designed position and flipped with respect to the planned position (IOL is implanted upside down). The theoretical model eye used was the Atchison model eye. Seven IOL designs of +27.00 diopters were used: a lens with negative SA to correct the corneal SA, a lens to partially correct the corneal SA, and a lens to not add any SA to the cornea (aberration-free IOL). These lenses were designed with the aspherical surface located on the anterior and posterior IOL surface. A lens with no aspherical surfaces was also included. For the optical quality analysis, the modulation transfer function (MTF) was used, together with the Zernike wavefront aberration coefficients of defocus, astigmatism, and primary coma. Results: Off-centring and tilting the IOL reduced overall MTF values and increased wavefront aberration errors. With the IOL correctly positioned within the capsular bag, an aberration-free IOL is the best choice for maintaining optical quality. When the IOL is flipped inside the capsular bag, the optical quality changes, with the aberration-free IOL and the IOL without aspheric surfaces providing the worst results. With the lens in an upside-down position, an IOL design to partially correct corneal SA shows the best optical quality results in decentration and tilt, in terms of MTF and wavefront aberrations. Conclusion: The aberration-free IOL is the best choice when minimal postoperative errors of decentration or tilt are predicted. With IOL flip, the negative SA lens design is the best choice, regarding the root mean square wavefront aberrations. However, in a proper IOL implantation, the IOL designed to partially compensate the corneal SA including asphericity on its posterior surface is the better possible option, even in the presence of decentration or tilt.

Freeform optics design method for illumination and laser beam shaping enabled by least squares and surface optimization

Freeform tailoring optics are core components in advanced illumination and laser technologies. In this work, we propose an efficient and streamlined optics design method to face the challenges in its implementation. We integrate ray-mapping least squares calculations with freeform surface optimization tools embedded in commercial optical design software. As a result, the complexity of freeform illumination and laser beam shaping design is significantly reduced by only adapting a built-in merit function. We demonstrate the feasibility of our approach through three design examples that provide tailored irradiance distributions. Furthermore, the results highlight the efficiency, simplicity and versatility of our approach that can be readily applied to multiple configurations.

Calculation of conic constants for thick lenses to get diffraction-limited images using 3rd order design and marginal skew ray tracing

We calculate equations to obtain the exact and third-order design of thick lenses free from spherical and coma aberrations at two points, at the edge and center of the lens, considering the shape factor and the conic constants. We obtained analytical expressions based on the equality of the optical path and the Abbe sine condition calculated for an object located in infinite and finite positions. Examples developed with this method show an alternative way of designing diffraction-limited thick lenses that are equal or better than results obtained when the conic constants are optimized using commercial optical design software. As the shape of the lens changes, the spherical and coma aberrations vary; so, the presented method offers better results for shape factors ranging from −0.5 to 0.9.

Comparing optimization algorithms for conventional and freeform optical design.

Five search algorithms from the literature of black-box optimization were implemented and applied to optical design problems. These algorithms are the Particle Swarm Optimization, Gravity Search Algorithm, Cuckoo Search, Covariance Matrix Adaptation Evolution Strategy and Nelder&Mead Simplex search. The performance of these search algorithms' implementations was assessed using the BBOB2009 (Black Box Optimization Benchmark) benchmark suite. These algorithms were compared in the context of two optical case studies, one with conventional rotationally symmetric optics and one with freeform optics. A comparison was performed against a commercial optical design software. Finally we provided a simple restart scheme applicable in the workflow of an optical designer. To the best of our knowledge, this is the first in-depth quantitative comparison of optimization algorithms for optical design.

Design of a reduced objective Lens fluorescence dPCR Gene chip detection system with high-throughput and large field of view

Achieving large FOV imaging and high resolution simultaneously for DNA detection poses an enormous conflict in the fluorescence microscope design field. As a result, this study sought to fill this gap by designing a system that is capable of producing the same quality imaging but of a simple, wieldy, cost-effective and unsophisticated nature. Therefore, we designed a dPCR gene chip detection system with high throughput, large field precision and reduced objective lens. This detection system can directly be used for imaging the fluorescence gene chip of 28 mm × 18 mm containing more than 20,000 channels. Three different kinds of fluorescence: FAM, HEX, and ROX can be used to capture images with a CMOS camera. The designed objective lens has a numerical aperture of 0.1 and a size reduction ratio of 1/2, capable of 20 mm working distance from objects, and with modulation transfer function (MTF) of more than 0.5 at 70lp/mm. Commercial optical design software ZEMAX was used to design the objective lens and control the aberrations by optimization operands. The Tolerance distribution and Monte Carlo tolerance analyses showed the design to be suitable for fabrication. According to the analyses, the detection system with the high-resolution ability of less than 10 μm (about 6um), thus, having low aberration and larger imaging scale is appropriate for DNA imaging. The designed gene fluorescent chip is expected to be adopted and utilized for the one-step imaging detection in clinical and bio application functions.

Joint digital-optical design of complex lenses using a surrogate image quality criterion adapted to commercial optical design software.

Like classical optical design, joint digital-optical design of complex lenses requires a skilled optical designer helped by powerful optical design software. Consequently, if optimization criteria have to be modified to take into account digital post-processing, the convenient optimization environment provided by commercial optical design software needs to be preserved. For that purpose, we define a joint-design criterion based on a merit function that contains terms classically implemented in optical design software but used in a non-standard way. After validation on a simple design problem, the proposed method is applied to the design of a very fast (f/0.75) complex lens. The obtained joint-designed lens is shown to be superior to a classically designed one in terms of weight and image quality in the field.

Flat Concentrator Photovoltaic System with Lateral Displacement Tracking for Residential Rooftops

We present a design for a flat concentrating photovoltaic (CPV) system that requires only lateral displacement for sun-tracking, intended for residential rooftop applications. Compared with flat-plate photovoltaics (PVs), CPV technology is essential for reducing the use of semi-conductor materials, which also enables cheaper solar power generation. Existing CPV designs are more bulky and complex than traditional PV panel techniques and are therefore better suited to solar farms than rooftop use. In this study, we explore an alternate approach, employing a mirror-coated lenslet array, to demonstrate a flat CPV system for rooftop installation. This mirror-coated lenslet array collects solar radiation and concentrates it with a very short focal length. The lateral movement of lenslet focal points according to a changing incident angle of sunlight allows for the use of a lateral displacement tracking mechanism. A square array of solar cells integrated on a transparent sheet is placed on top of a mirror-coated lenslet array to collect focused sunlight and convert it to electricity. The proposed CPV panel can be achieved with a 35 mm thickness. Simulation models were developed using commercial optical design software (LightTools). The simulation demonstrates an optical efficiency of up to 89.5% when the concentration ratio of the system is fixed to 50×. The simplicity of the structure enables cheaper mass production. Our quest for a lateral displacement sun-tracking mechanism also shows that the system has a high tolerance, thereby enabling cost savings by replacing a highly precise, active sun-tracking system with a lower-accuracy system. The presented flat CPV is a strong candidate for a low-cost, high-efficiency solar energy system that can be installed on the rooftops of residential buildings to deliver energy savings.

Design of apochromatic lens with large field and high definition for machine vision.

Precise machine vision detection for a large object at a finite working distance (WD) requires that the lens has a high resolution for a large field of view (FOV). In this case, the effect of a secondary spectrum on image quality is not negligible. According to the detection requirements, a high resolution apochromatic objective is designed and analyzed. The initial optical structure (IOS) is combined with three segments. Next, the secondary spectrum of the IOS is corrected by replacing glasses using the dispersion vector analysis method based on the Buchdahl dispersion equation. Other aberrations are optimized by the commercial optical design software ZEMAX by properly choosing the optimization function operands. The optimized optical structure (OOS) has an f-number (F/#) of 3.08, a FOV of φ60 mm, a WD of 240 mm, and a modulated transfer function (MTF) of all fields of more than 0.1 at 320 cycles/mm. The design requirements for a nonfluorite material apochromatic objective lens with a large field and high definition for machine vision detection have been achieved.

Design of high resolution panoramic endoscope imaging system based on freeform surface

This paper introduces a novel endoscope design based on the panoramic annular staring imaging technology. This design utilizes a single optical system to realize both panoramic observation and local high resolution on a single sensor. The freeform surface is employed to improve the image quality and reduce system volume. The design results based on the commercial optical design software package ZEMAX, indicate that this optical system is able to acquire an excellent image quality with a modulation transfer function above 0.6. Compared with the traditional ones, this novel endoscope design with wide FOV is likely to decrease the diagnostic time dramatically and improve the lesion detect rate considerably.

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.

Optical design of contact lenses using principal component analysis method with Taguchi method

In this study, an optimal contact lens design for myopia and astigmatism eyes was proposed. In addition to the optical parameters of the human eye, the physiologically relevant parameters of design have become the subject of increased focus. If we compacting overall volume size, the value of spherical aberration (SA) at wide radius of contact lens seems lower. If we corrected the design to improve the value of SA, modulation transfer function (MTF) and coma aberration (TCO) value would become lower relatively. Hence we integrated the optimal method of Taguchi method and mathematical analysis scheme of principal component analysis (PCA) to optimize the multiple quality characteristics (SA, TCO and MTF) of the contact lens. By combining Taguchi and PCA methods, a set of optimum design parameters was well selected to balance the values of SA, TCO and MTF that improve the SA 25.63%, TCO 91.88% and MTF 2.4% than commercial optical design software of CODE V.

Analytic aspheric coefficients to reduce the spherical aberration of lens elements used in collimated light.

We provide closed-form formulas for aspheric terms for either plano-convex or convex-plano aspheric lenses as functions of the paraxial parameters involved in the process of refraction. These formulas are obtained through an expansion in Taylor's series from the exact caustic equation produced by aspheric lenses considering a plane wavefront propagating parallel to the optical axis and impinging on the refracting surface. A comparison of the aspheric coefficients obtained through our analytic formulas and commercial optical design software is presented, showing good agreement. This is useful in reducing spherical aberration.

The Optical Design of Achromatic Phase Matching System Based on ZEMAX

The system of achromatic phase matching (APM) based on grating pairs is designed by the commercial optical design software ZEMAX. Firstly, we theoretically calculate the theoretical incident angular where each frequency components exactly reaches the phase-matching in nonlinear crystals. Subsequently, the model of APM system is built and optimized in ZEMAX. The results are well in accordance with the theoretical ones. In addition, the effects of grating frequency and aberration produced by the focus lens on APM scheme are analyzed.

Optical Design and Optimization of a Micro Zoom System with Liquid Lenses

A micro zoom system without moving elements by use of two liquid lenses is designed and optimized in this paper. The zoom equations of the system composed of two liquid lenses are deduced. The structure parameters including radius and thickness of a conical double-liquid electrowetting based lens are analyzed and calculated. Because the liquid thickness varies non-linearly with the radius of the interface, it's very difficult to optimize a real liquid lens using commercial optical design software directly. Through the Application Programming Interface (API) of the optical design software CODE V, a zoom system with two real electrowetting based liquid lenses is modeled and optimized. A two-liquid-lens zoom system without moving elements, with a zoom factor of 1.8 and a compact structure of 10 mm is designed for illustration. This can be useful for the camera design of mobile phones, tablets and so on. And this paper presents a convenient way of designing and optimizing a zoom system including liquid lenses by commercial optical design software.

Automatic clocking optimization for compensating two-dimensional tolerances

Clocking of lens elements is frequently used as an effective method of compensating for two-dimensional tolerances such as material inhomogeneity and surface figure errors. Typically, the lens designer has to determine the optimum angles of rotation by manually modeling lens element clocking in the commercial optical design software because the nature of errors resolved by lens clocking does not lead to good convergences for clocking optimization. In this paper, a method of automatic clocking optimization is developed. The method is implemented using a combination of particle swarm optimization algorithm and commercial optical design software. The optimum angles of rotation and predicted imaging performance are automatically calculated using this method. Methods of implementation and optimization examples are also given.

Optimization of wavefront-coded infinity-corrected microscope systems with extended depth of field

The depth of field of an infinity-corrected microscope system is greatly extended by simply applying a specially designed phase mask between the objective and the tube lens. In comparison with the method of modifying the structure of objective, it is more cost effective and provides improved flexibility for assembling the system. Instead of using an ideal optical system for simulation which was the focus of the previous research, a practical wavefront-coded infinity-corrected microscope system is designed in this paper by considering the various aberrations. Two new optimization methods, based on the commercial optical design software, are proposed to design a wavefront-coded microscope using a non-symmetric phase mask and a symmetric phase mask, respectively. We use polynomial phase mask and rational phase mask as examples of the non-symmetric and symmetric phase masks respectively. Simulation results show that both optimization methods work well for a 32 × infinity-corrected microscope system with 0.6 numerical aperture. The depth of field is extended to about 13 times of the traditional one.

Simulation and analysis of nonlinear self-focusing phenomenon based on ray-tracing

The simulation of nonlinear self-focusing phenomenon using ray-tracing method can macroscopically provide an intuitive picture of the propagation of light in a self-focusing material, without adopting paraxial approximation or self-similar hypothesis. In this paper, propagation of light is sampled by discrete slices along a certain direction. Thus nonlinear propagation is turned into the combination of optical modulation of the refractive index on separate slices and linear propagation between each two adjacent slices. On each slice, after calculating the flux, we use a novel algorithm to suppress the quantized errors. For the linear propagating process, Adams method is adopted to solve the ray equations, which solve the problem that the widely used Runge-Kutta method cannot be used in simulation of light in nonlinear materials. The simulation results reveal that there are several foci along the propagating axis and the location of the first focus becomes closer to the incident plane as the power of light goes up. Furthermore, because the program traces real rays, it is possible to reach the non-paraxial region and reveal the phenomenon of ring-structure flux distributions caused by self-focusing. This is significant for the safety of high-power laser systems. Some commercial optical design and simulation software are also based on ray-tracing methods. Thus the systems including both nonlinear and linear materials are possible to simulate, which can guide people to set up the corresponding experimental systems.

Effects of structured mid-spatial frequency surface errors on image performance

Optical designers are encouraged to adopt aspheric and free-form surfaces into an increasing number of design spaces because of their improved performance. However, residual tooling marks from advanced aspheric fabrication techniques are difficult to remove. These marks, typically in the mid-spatial frequency (MSF) regime, give rise to structured image artifacts. Using a theory developed in previous publications, this paper applies the fundamentals of MSF modeling to demonstrate how MSF errors are evaluated and toleranced in an optical system. Examples of as-built components with MSF errors are analyzed using commercial optical design software.