Conference Agenda

Adaptive Optics (AO) is a key technology to enhance the imaging performance of ground based astronomical telescopes, compensating the atmospheric aberrations through an adaptive mirror. To enhance the efficiency of these AO systems, many observatories aim to integrate the adaptive mirror within the secondary mirror of the telescope, resulting in an adaptive secondary mirror (ASM).

TNO is developing ASM’s based on a unique and highly efficient electromagnetic actuator technology, which high force output enable the use of relatively thick mirror shells (>3,5mm), and no need for active cooling through their high energy efficiency. These aspects lead to an overall highly robust and reliable ASM system, which is considered a key requirements for such active components that are built into the heart of the telescope.

TNO has realized two prototypes ASM systems for the NASA IRTF telescope (Ø24cm,and 36 actuators, readily installed and tested) and the UH-88 telescope (Ø62cm and 204 actuators, currently going through factory acceptance testing). In this talk the recent results of these ASM’s will be presented. Furthermore, an outlook will be provided on the future developments including the ASM for the KECK telescope (Ø1.4m and ~3400 actuators).

This work discovers two hidden cases of blockwise recurrence in Zernike computations. Based on these findings, a new computation scheme for Zernike polynomials is proposed. It uses one Pascal triangle for all internal factors, thus avoiding calculations of factorials, cos/sin, inverse matrix, etc., and meets the requirements of computatonal accuracy, high speed, low memory footprint, and flexibility.

Mid-Spatial Frequencies (MSFs) are structured surface errors on

optical elements that often require a full wave-optics treatment beyond the limits

of geometrical approximations. Within the context of paraxial scalar wave-optics,

we introduce the Grating Mode Series Expansion (GMSE) method—an

efficient approach for modeling MSF propagation through astigmatic, first-order

optical systems. By decomposing wavefront perturbations into discrete grating

modes on top of an envelope beam, GMSE enables the analytical propagation of

each mode, accurately capturing interference effects and spatial energy redistribution.

The framework is further developed into an algorithm that sequentially

models both form errors as well as MSFs, at arbitrary distances from pupil

planes. From this method, we derive intuitive shift relations that reveal three

key phenomena: (a) MSFs can induce measurable beam shifts at apertures, (b)

even weak MSFs can produce significant non-uniformities in pupil-plane irradiance

due to interference, and (c) the transition between imaging degradation

and stray-light contribution is formalized as a function of system parameters.

The method and its implications are demonstrated through representative case

studies and form the back-bone for the description of MSFs propagation in nonparaxial

systems.

Global optimization in optical design is particularly challenging for aspheric and freeform surfaces due to their complex, non-symmetric nature and the presence of numerous local minima in high-dimensional design spaces. Traditional optimization methods often struggle to efficiently escape these local minima, leading to suboptimal solutions. To address this, we propose the Simple Saddle Point Detection (SSPD) Algorithm, which enhances optimization by systematically identifying transition points that connect different design regions. By leveraging these pathways, the algorithm enables a more structured exploration of the design space, improving the convergence toward high-performance solutions. This study applies the SSPD approach to optimize complex optical systems, including catadioptric and multiple (folded) imaging mirror systems, where conventional methods face significant limitations. The results demonstrate that this approach is highly effective in refining aspheric and freeform optical designs, facilitating more efficient and reliable global optimization. Finally, we present the global search results as a closed network, highlighting the capability of SSPD to navigate complex design landscapes and achieve superior optical performance.

Increasing accuracy requirements for optical systems require taking thermal disturbances into account at an early stage of the design process. Therefore, a simulation method is presented with a mesh-based absorption algorithm, to account for the temperature distribution in a lens. Having this information, e.g., temperature dependent material properties can be used or thermal deformations can be considered.