An exploration of the freeform two-mirror off-axis solution space

Volatier, Jean-Baptiste; Duveau, Louis; Druart, Guillaume

doi:10.1088/2515-7647/ab5c0d

Cited by 7 publications

(3 citation statements)

References 18 publications

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“…A first strategy involves the so-called direct design methods. They rely on solving geometrical or differential equations describing the freeform optical system under study to achieve a wellperforming initial design [23][24][25][26][27][28][29][30][31] . Although these methods show clear merits, so far, they lack a straightforward path to increase the number of optical surfaces that can be calculated 25,29,31 .…”

Section: Freeform Optical Design Strategiesmentioning

confidence: 99%

Freeform imaging systems: Fermat’s principle unlocks “first time right” design

Duerr

Thienpont

2021

Light Sci Appl

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For more than 150 years, scientists have advanced aberration theory to describe, analyze and eliminate imperfections that disturb the imaging quality of optical components and systems. Simultaneously, they have developed optical design methods for and manufacturing techniques of imaging systems with ever-increasing complexity and performance up to the point where they are now including optical elements that are unrestricted in their surface shape. These so-called optical freeform elements offer degrees of freedom that can greatly extend the functionalities and further boost the specifications of state-of-the-art imaging systems. However, the drastically increased number of surface coefficients of these freeform surfaces poses severe challenges for the optical design process, such that the deployment of freeform optics remained limited until today. In this paper, we present a deterministic direct optical design method for freeform imaging systems based on differential equations derived from Fermat’s principle and solved using power series. The method allows calculating the optical surface coefficients that ensure minimal image blurring for each individual order of aberrations. We demonstrate the systematic, deterministic, scalable, and holistic character of our method with catoptric and catadioptric design examples. As such we introduce a disruptive methodology to design optical imaging systems from scratch, we largely reduce the “trial-and-error” approach in present-day optical design, and we pave the way to a fast-track uptake of freeform elements to create the next-generation high-end optics. We include a user application that allows users to experience this unique design method hands-on.

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Section: Freeform Optical Design Strategiesmentioning

confidence: 99%

Freeform imaging systems: Fermat’s principle unlocks “first time right” design

Duerr

Thienpont

2021

Light Sci Appl

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“…To produce an image of the scene with such a satellite, using a pushbroom technique is very useful to have a simple and compact instrument. As presented in 6 and in figure 1 a two mirror freeform telescope is sufficient for this kind of mono-dimensional FOV.…”

Section: Specificationsmentioning

confidence: 97%

Design strategies of an unobscured three mirror telescope with freeform surfaces for infrared nanosatellite imagery

Duveau

Lépine

Hugot

et al. 2021

International Conference on Space Optics — ICSO 2020

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The new degrees of freedom offered by the new family of freeform surfaces helps compensating for off axis aberrations in optical designs. We define a freeform surface as a non-rotationally symmetric surface which cannot be described as an off-axis part of a conicoid. The use of freeform surfaces allows an increase in performance such as on the field of view, the F-number and compactness of unobscured all reflective telescopes. Reflective designs have the advantage of being light, achromatic, and potentially low-cost due to cheaper materials involved. It could result in industrial production of compact panchromatic systems for various applications ranging from automotive sensors to imaging nanosatellites. In this paper we address the challenges posed by the use of these surfaces in optical design optimization, specifically the minimization of the surface counting, in order to simplify the manufacturing, assembly and integration phases. We focus on three mirror designs and work on the compactness with various flavors in the 3D space. We will discuss our results on a fast, unobscured, non reimaging and well corrected three mirror anastigmat (TMA) design for a nanosatellite thermal imaging payload using uncooled bolometers. Optimization method of a TMA under volume and straylight constraints is described. A tolerance analysis is performed and minimal alignment is required even for large tolerances.

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“…Previous works studied the solution space for two mirror freeform designs (Trumper et al, 2020;Volatier et al, 2019;Steven and Dubra, 2017). Such systems are simple to manufacture due to a reduced amount of surfaces, leading to a relatively easy alignment process but are more suited for linear field of view and does only allow a limited correction of the wavefront.…”

Section: Introductionmentioning

confidence: 99%