Rudolf Kingslake is widely regarded as one of the founders of modern optical design. When educating his students at The Institute of Optics, Professor Kingslake championed the importance of lens design fundamentals as a complement to computer-aided design. At that time, ray tracing speed was a major bottleneck in the lens design process. Now that lens designers can trace rays in fractions of a second and have access to powerful computational tools like global optimization and AI are these same fundamentals needed? Should we keep teaching them? One of Kingslake’s biggest fears was that we would forget “our laboriously acquired knowledge of geometrical optics and substitute for it the mathematical problem of optimizing a merit function”.

There is no question that computers have done wonders for lens design and have enabled far more advanced designs than thought possible. The issue at hand is if mastery of both lens design fundamentals and computer software is required for success. Unfortunately, the current educational landscape places much more emphasis on the latter than the former, and many of the fundamentals impressed by Kingslake have been lost. However, three boxes of index cards belonging to Rudolf Kingslake were recently uncovered. Included in the collection are 171 lens design exam problems which present a fascinating perspective on lens design as it was taught in the pre-computer age. In this talk we’ll take a closer look at several of these forgotten problems and discuss how their solutions are still relevant for modern lens design today.

Freeform optics, generally defined as optics without an axis of rotational symmetry, can be very useful for increasing performance while reducing size, weight, and element count in optical systems. Examples will be presented, ranging from one-off astronomical telescopes to optics for high-volume consumer devices. Although they can enable systems that would not otherwise be possible, freeform optics present significant challenges to designers and manufacturers. These challenges include finding a common language for design and fabrication, fabrication techniques, and especially metrology techniques. Potential solutions to some of these challenges will be discussed.

The Nancy Grace Roman Space Telescope (“Roman”) was prioritized by the 2010 Decadal Survey in Astronomy & Astrophysics and is NASA’s next astrophysics flagship observatory. Launching no earlier than 2026, it will conduct several wide field and time domain surveys, as well as conduct an exoplanet census. Roman’s large field of view, agile survey capabilities, and excellent stability enable these objectives, yet present unique engineering and test challenges. Roman comprises a Spacecraft and the Integrated Payload Assembly (IPA), the latter of which includes the Optical Telescope Assembly (OTA), the primary science Wide Field Instrument, a technology demonstration Coronagraph Instrument, and the Instrument Carrier, which meters the OTA to each instrument. The Spacecraft supports the IPA and includes the Bus, Solar Array Sun Shield, Outer Barrel Assembly, and Deployable Aperture Cover. It provides all required power, attitude control, communications, data storage, and stable thermal control functions as well as shading and straylight protection across the entire field of regard. This paper presents the Observatory as it begins integration and test, as well as describes key test and verification activities.

The Screen Image Synthesis meter was proposed to make high-speed BSDF measurement and whole field measurement, but it lacks the spectrum information. We proposed a snapshot hyperspectral technology and applied it to the SIS meter to build up a SIS hyperspectrum meter. It released the full power of SIS system. Besides, the proposed method doesn’t need to add any other bulky optical element. The experiments demonstrated the measurement is trustable in both spectrum distribution and color coefficient temperature distribution.

Minimizing glare and ghost images in optical systems via stray light control constitutes a significant portion of design time and costs. Optical coatings are crucial for reducing stray light to improve the signal-to-noise ratio (SNR). However, existing tools for identifying problematic surfaces are often manual, prompting extensive coating application to avoid extended development, which increases optics cost. To facilitate stray light analysis and reduce cost, a standalone tool has been developed that inquires about stray light optical path irradiance and assesses components' contribution to noise using realistic illumination scenarios. Coatings can be selectively applied to problematic surfaces until the desired SNR is attained. This approach significantly reduces analysis time and costs. GPU and Cloud computing expedite computations while maintaining precision and integrating seamlessly with Ansys' advanced ray-tracing tools, avoiding assumptions or approximations. It utilizes complete non-sequential ray data within a semi-sequential framework. Use cases and SNR analysis to validate the tool will be presented.

In this paper, we present our investigation into the prevention of blue-light leakage in phosphor-converted white LEDs through a passive approach. Our study primarily focuses on the application and optimization of a specific thermochromic material known as Crystal Nano Cellulose (CNC). We integrated CNC within the epoxy lens of white LEDs. Importantly, under normal operating conditions, CNC minimally affects the optical properties of the emitted white light. However, in instances of overheating where blue-light leakage occurs, the temperature rise induces a darkening effect in CNC. By incorporating CNC as a responsive material in the design of white LEDs, our study offers a practical and efficient solution to address the adverse effects of blue-light leakage resulting from overheating. This enhancement not only improves the safety and comfort for users but also serves as an early warning mechanism for the aging of phosphor-converted white LEDs.

The field of lens design has changed in many ways over the last quarter-century. Not only have the design tools changed, but the types of systems being designed have also changed. In this presentation we look back on how in design problems have changed and how optical design tools have changed to support new types of design problem.

The Transport of Intensity Equation (TIE) is a partial differential equation that describes the relationship between the phase and the axial intensity variation of an optical field. The essence of phase retrieval using the TIE is to solve the partial differential equation under appropriate boundary conditions. Ichikawa, Lomman, and Takeda (ILT) verified the TIE experimentally for the first time, solving the equation by the Fourier transform method, thus obtaining the quantitative phase distribution of a one-dimensional sample. In this paper a modification of the Ichikawa-Lohmann-Takeda (ILT) method is presented. We extent the method using cylindrical coordinates for phase retrieval. The main idea is to replace the grating used in the original ILT method for a concentric-circular grating in order to exploit the circular symmetry. Typically, the method implemented by ILT results in the solution of the Poisson Equation. The latter is resolved through a process based on artificial neural networks. Experimentally the phase is compared using the Schack-Hartmann sensor versus the solution found by solving the circular TIE.

A few very simple optical systems with just one or two mirrors can show quite surprising aberration correction behavior under certain circumstances.

A neural network based generative optimization algorithm was investigated for designing athermalized lens design. In particular, deep learning framework was developed by employing PyTorch and incorporated lens variable conversion techniques along with a differentiable ray tracing module. The framework, combining supervised optimization with unsupervised optimization, could generate diversified lens designs starting from reference lens system including aspheric surfaces. Our generative optimization algorithm could also be applied to the design of athermal lens systems that minimize thermal focus shift with temperature changes. In addition, using the developed algorithm and considering the first order thermal expansion coefficient of each lens, we were able to design an all-plastic athermal lens system composed of polycarbonate and polymethyl methacrylate materials. The RMS spot size averaged over all fields and Seidel aberration were minimized for thermally expanded lens systems at various temperatures. The developed framework is expected to help lens designers create optimal designs.