This PDF file contains the front matter associated with SPIE Proceedings Volume 11814, including the Title Page, Copyright information, and Table of Contents.

We applied an extended version of the Niching-CMA-ES heuristic to search for local minima of the Cooke triplet, a renowned photographic lens design, of which 21 local minima were already known. The considered problem is defined by 6 input (decision) variables, namely the curvatures of the three lenses present in the Cooke triplet, and is driven by a single objective function, that is the RMS spot size. The applied approach found: (i) 19 out of the 21 known minima in a single run; (ii) 540 new local minima with objective values lower/equal to those of the known 21 minima; (iii) a large number of infeasible designs.

Freeform technology is one of the most promising solutions to enhance the performance of optical systems. Aiming to demonstrate the freedom and flexibility of optical system design, several challenging design examples using freeform surface are presented, including two wide-angle camera lenses adopting even and odd pedal polynomial formulations for symmetric optical surface description, and an anamorphic cinema lens employing non-rotationally symmetric surfaces for capturing a wider aspect ratio and offering a 1.33X squeeze factor on a 4:3 sensor size. Methods and constraints for designing and optimizing the optical systems are discussed. The optical performances of these design examples are analyzed. The results verify the practicability and effectiveness of the proposed formulations and design strategies in the field of freeform imaging optical design.

An ultrashort throw lens with a catadioptric relay (USTCR) for curved screens has a half-field angle greater than 110°. The angle of the principal ray incident on the aspherical mirror increases according to the height of the ray emitted from the object surface. A larger field angle leads to larger sag amount. Thus, the degree of difficulty in precision machining increases. In this study, we examined how the tangent of the concave mirror surface can be reduced such that it can be manufactured while maintaining the half-field angle and its optical performance. It was found that the interval between imaging points reaching the screen can be made constant by suppressing the change in the principal ray incident on the concave mirror by +/- 1° or less, particularly in the area of a half-field angle of 90° or more, and making the change in the tangent of the concave mirror surface constant. As an index of distortion, we show that the perimeter ratio (Pr) of the frame length, which was equally divided by 5×5 in the screen, improved from 0.26 to 0.73. As one possible application, a projection system that can be realized with only 8 projectors is proposed, as opposed to conventional systems consisting of approximately 20 projectors in omni-directional projection systems.

Aberrations of the eye degrade the ocular point-spread function thereby reducing the attainable visual acuity. It is common practice to distinguish between lower and higher-order monochromatic aberrations of the eye when differentiating between what can be corrected with sphere and cylinder, and what cannot. Nevertheless, at the retina it matters more whether light is incident along or obliquely onto the elongated photoreceptors. In this contribution, I discuss the impact of different Zernike aberration terms not at the pupil, but at the retina. Even-ordered monochromatic Zernike aberrations have an associated wavefront slope at the retina whereas odd-ordered Zernike aberration modes have no wavefront tilt across the point-spread function. In other words, even and odd-ordered Zernike modes are affected differently by the Stiles-Crawford effect of the first kind that relates to obliqueness of light at the retina. Understanding this is essential to decode how vision is triggered in normal viewing conditions as well as when probing vision and photoreceptors with psychophysical methods in the analysis of vision or for ophthalmic design. Finally, a uniaxial pupil flicker system is used to directly measure the integrated Stiles-Crawford effect in the author’s eye in order to assess apodization of oblique light in normal vision.

We present a method to calculate the spatio-temporal electric field distribution of ultrashort focused pulses propagating in a nonlinear medium with no absorption. The method combines the angular spectrum technique, for propagating light beams, with the irradiance-dependent refractive index of the medium. We modeled the propagation of ultrashort mildly focused pulses, with different durations and peak powers, inside a Ti:sapphire crystal characterized by its linear and nonlinear refractive indices. Our method is able to reproduce the selffocusing effect expected for nonlinear materials for incident beams with powers above the critical power. We analyze the dependence of the focal length and spot size within the nonlinear medium on the incident power and compare them with the focal length and spot size for the same focusing lens in free space. We also analyze the spot size and pulse duration as a function of the distance traveled in the nonlinear medium for several incident powers. Finally, we analyze the effect of the nonlinear medium refractive index on the spatio-temporal distributions of the focused pulse.

Active optical components are essential building blocks for a wide variety of applications such as optical communications, microscopy, and illumination systems. Reconfigurable metasurfaces, which consist of arrays of subwavelength meta-atoms, can be engineered to uniquely realize compact and multifunctional optical elements, enabling light-polarization dynamic-control as well as beam steering, focusing or zooming. Varifocal metalenses, in particular, have attracted increasing interests. Yet, going beyond mechanical modulation schemes to realize ultra-thin devices with fast modulation remains challenging due to the complex phase and phase-delay profiles involved. Recently, thermooptical effects in dielectric nanostructures have emerged as a promising solution to tune their optical resonances, offering unexplored opportunities for ultra-thin reconfigurable metalenses, in particular silicon based ones. In this work, we report a proof-of-concept design of an ultrathin (300 nm thick) and thermo-optically reconfigurable silicon metalens operating in the visible regime (632 nm). Importantly, we demonstrate that, using thermo-optical effects, it is possible to achieve continuous modulation of the focal-length at a fixed wavelength. In particular, operating under right-circularly polarized light, our metalens exhibits a linear focal shift from 165 μm at 20°C to 135 μm at 260°C, exceeding the lens focal depth. The average conversion efficiency of the lens is 26%, close to mechanically modulated devices, while its Strehl ratio is 0.99, confirming a diffraction-limited performance. Concurrently, in this work we report an automatized methodology to design a reconfigurable metalens, compute its layout and verify the expected performance. Overall, we envision that, by further optimization of the optical response of individual meta-atoms with machine-learning algorithms, thermally-reconfigurable silicon metalenses will emerge as a viable, chip-compatible solution to realize ultrathin varifocal lenses.

Receiver field of regard is one of the major problems for free space optical (FSO) communications. Drift or vibrations in transceiver orientations reduces effective communication time. The methods implemented to overcome this limitation, often require bulky optical and complex mechanical assemblies with feedback control, that are not suitable for long run operation in an airborne system. In this paper, we propose a novel receiver system that can effectively reduce the impact of pointing errors. The system is composed of two metalenses and one off-the-shelf conventional lens. The first metalens focuses optical beam incident at different angles on the aperture, at different locations on focal plane. The second metalens is placed on the focal plane of first metalens. After passing through the second metalens, the beams become parallel to optical axis of the receiver optical system. The parallel beams are collected by a suitable off-the-shelf aspheric lens and focused back on single detector that sits on a point on the optical axis. The system is designed and analyzed by physical optics theory. With 0.5 mm receiver aperture and 50 mm diameter aspheric lens, Zemax simulation shows that the system can collect +/-5-degree incident angle with detector diameter of 273μm. COMSOL frequency domain simulation with smaller diameter beam shows that the efficiency of the 2 metalens system is about 80%. Efficient metalens design and beam compression at detector plane are two key features of the proposed system. The system relaxes the strict requirement of aligning the transmitter and receiver unit in FSO communication.

Plenoptic cameras capture the spatial and angular information of a scene. The use of plenoptic cameras in areas such as research, microscopy, industry and consumer markets has steadily increased over the past two decades. When designing a plenoptic camera a decision must always be made between spatial and angular resolution. Many factors such as the size and number of microlenses in a microlens array or the relative position of the microlens array and sensor to the main lens play a role. Here we examine the two most common designs of plenoptic cameras. The plenoptic cameras 1.0, also called the unfocused plenoptic camera, and the plenoptic cameras 2.0, the focused plenoptic camera. We derive the mathematical equations that describe the connection between spatial and angular resolution. Supported by experimental results we show the relationship between the equations and a real object with different object distances taken from the plenoptic camera 1.0 and 2.0. These analyzes make it easier for researchers and engineers to choose the right camera design for a particular application. The user only has to determine beforehand which depth-of-field or which spatial resolution is needed.

This paper presents the method and experimental results of the construction and reconstruction of three dimensions conical holography. He-Ne laser is used as the construction light source. Then the construction light is shone on top of a transparency conical cup, where a plain holographic film is wrapped around and attached to its surface. The object is located at the bottom of the cup. In this manner, the cup acts as a captured screen. After exposure, the film is developed and fixed by a chemical solution. The three-dimensional holography is recorded in the film. For reconstruction, we used red LED and flashlight as a reconstruction light source. The film is wrapped around and attached to the surface of the cup again. When the reconstruction light shines on the cup, the three-dimensional holography appears in the center of the cup. The cup is rotated in step, each step is 45 degrees, and the image is recorded by the digital camera. Experimental results show that the 360 degrees three-dimensional holographic image is successfully reconstructed. In conclusion, we could apply the method to create a three-dimensional holographic for displaying in all directions.

LED lighting provides considerable flexibility for shaping the light spectrum for different applications, including increasing the color gamut. While the spectra are typically designed for their effects on observers with normal color vision, the chosen spectra could also enhance color perception in color-deficient observers (Tamura et al. 2015, 2017), and could potentially emulate the effects of filter aids for color deficiencies. We examined the consequences of typical or wide-gamut luminaires for color deficient observers. Protanomalous and deuteranomalous individuals have altered L- or M-cone spectral sensitivities that result in a compression of the color contrasts along the L vs. M axis of cone-opponent space. Light sources designed to increase these contrasts would thus be expected to amplify the L vs. M signals for color-deficient observers. We modeled the effects of different luminaires on color contrast for normal trichromats and protanomalous or deuteranomalous observers. For this we notionally illuminated the spectral reflectances of Munsell surfaces that were selected to yield a uniform circle of 36 hues in a cone-opponent space under an equal energy white luminaire for a color normal trichromatic observer. We then illuminated these surfaces with typical illuminants and the Rec.2020 UHDTV wide color gamut standard to evaluate chromatic contrast for color-anomalous observers and normal trichromats. The results illustrate the potential for modern wide-gamut light sources to enhance color contrast for anomalous trichromats.

We demonstrate an iterative and inverse design of a segmented reflector used to illuminate the road with a uniform light distribution and reduced glare to the oncoming traffic. Design is set to meet the StVZO standard. The maximum brightness obtained is 1460 candela, which is five times brighter than a conventional headlamp of urban shared electric scooters and bicycles, resulting in improved visibility in dark environments. A prototype was built and tested at various environments. The tolerance analysis showed no negative influence on the desired standard light distribution. In addition to this iterative approach, a ray tracing code has been developed for inverse design and to map a desired uniform road illumination pattern back to the candela sensor for corresponding reflector design.

A significantly large amount of thermal energy is lost from or gained in buildings as a result of solar radiation. A comfortable temperature can be maintained by correctly designing and arranging a building’s windows and smart roof coatings. Single layer or multilayer thin film coatings, with spectrally desirable characteristics, are deposited on glass or roof surfaces and can greatly improve a building’s energy efficiency. Thermochromic materials present some advantages due to their reversible color and phase change behavior near ambient temperature. For example, a thermochromic coating on a roof’s surface can change color (black to white) reversibly when heated at around 30 °C, reflecting solar radiation and reducing a building’s cooling needs. In the present study, various thermochromic coatings on glass slides are investigated. In this work, the effect of non-toxic titanium dioxide (TiO₂), used as a UV radiation protective coating on thermochromic particles (such as a three-component blue dye synthesized in the lab or a commercially available black dye), is discussed. The composite coatings of the chosen components can reduce a building’s cooling and heating energy needs and provide an environmentally sustainable solution for a green economy. Several physico-chemical characterization techniques were used to understand the surface, interfacial, spectroscopic, and thermal behavior of TiO₂ or SiO₂ coatings and phase change thermochromic materials for applications in thermal storage and enhanced energy efficiency.

"Lens Design Technical Event"

The Talbot effect is a phenomenon that is also often known as self-images or images without a lens. Such an effect is manifested by a periodic repetition of optical field distributions at certain distances from an aperture. We present a mathematical development, based on the Fourier transform in polar coordinates to solve this case.

Photoacoustic imaging(PAI) is a emerging powerful and efficient imaging technology. Optical-resolution photoacoustic microscopy is an useful photoacoustic imaging technique combining the advantages of both optical imaging and acoustic imaging which obtains many attractive advanges such as high resolution, high contrast and so on. Laser beam is often focused strongly to achieve high resolution. However, this will lead to a poor depth-of-field and less structural information which limits the further application of this technology. Aimage fusion method based on CNN feature extraction is proposed to achieve large volumetric optical-resolution photoacoustic microscopy. First, two groups of simulated 3D photoacoustic data of different focal locations were obtained through photoacoustic microscopic imaging platform. Then B-scan data were fused and maximum projection of the reconstructed 3D data is taken to display the photoacoustic information. By comparing the source images and the fused image, we show that the proposed method can be implemented to obtain large volumetric and high-resolution photoacoustic images.

Demand for High NA objective lenses with diffraction limited image quality is growing. This demand translates in design more complex optical system with many optical components. In order to optimize the most favorable arrangement of optical components new design methodology based on functional separation lens group in high numerical aperture (NA) objective was developed. For this purpose, all lens components were divided on the three-lens group: front group, middle group and output lens group. The front lens group includes front lens (thick meniscus for dry type of objective or thick plano-convex lens for immersion objective) and several aplanatic shape meniscus lenses. The middle lens group consists of several cemented lens components (doublets or triplets) and output lens group includes “Double Gauss” lens system or combination of cemented doublet with one or two singlet lenses. The total number of lenses in such types of optical system can reach 15-16 or even more. Design an optimal composition (optical components arrangement) for high numerical aperture objective lens will be discussed. Quantitative related parameter for optimal objective lens component’s structure will be proposed.

Based on technological achievements artificial lighting is changing all over the world. The involved changes, mainly driven by minimizing electric energy consumption, imply the replacement of almost every traditional light source by light- emitting diodes (LEDs) in almost every level of human activities. An incipient rapid transition is being carried out on a massive scale since a decade; this fact is still cause of concern and controversies from some researchers, experts, professionals, associations and the public in general. Several characteristics of the new lighting sources including LED screens have been proven to affect individual visual and non-visual health (i.e., digital eye syndrome and disruption of circadian rhythms) as well as general well- being (threats to ecosystems); furthermore, there are claims that regulations should be rethought. This paper provides a panoramic view of several aspects of the problematic posed by new artificial light sources. The main focus of this preliminary work is aimed at presenting and discussing the spectral characteristics of representative cases of commercial domestic lamps (incandescent, fluorescent and LED units) and screens (cold cathode fluorescent and LED units) which are ubiquitous in everyday life of Argentinian society. Given that some sources have important spectral content in the phototoxic region (400- 500 nm), palliative often suggested strategies employing transparent and pigmented commercially available filters as well as free software, were evaluated. Results show that the studied strategies perform within a large range of attenuation in the way they block short wavelengths.

During the last two decades, Liquid Crystal Variable Retarder (LCVR) technology has matured and advanced as reliable and well-understood technology for ground applications to the point of being recently integrated in space-based optical instruments for the first time. LCVR cells use nematic liquid crystals to electronically tune the birefringence of the device in order to control the polarization of the transmitted light. The possibility to modulate the light polarization by means of an applied voltage offers the advantage of replacing the conventional rotary mechanisms, dedicated to carry the polarizing optics. Consequently, LCVR cells represent an excellent electro-optic solution to include in the design of space instruments where polarized light modulation is necessary. However, to validate the applicability of a LCVR cell to a space mission it is imperative to test its survivability in its exposure to conditions representative of the space environment. In this article, we summarize the activities performed to test the survivability of two commercial LCVR samples after their exposure to space-like environment for radiation and we report the result obtained by analyzing the radiation dose impact on the cell performances. The under-test samples have been produced by Meadowlark Optics Inc and designed for operation at 547 nm. We exposed the cells to multiple levels of gamma radiation dose, measuring their response time after each dose. To verify the impact of the accumulated radiation dose on the optical performances of the LCVR, we chose as indicators the retardance versus voltage, the transmission, and the response time. We measured these quantities before and after the whole test campaign and compared the two datasets to verify if gamma rays introduced any alterations in cell performances.