SMS-based optimization strategy for ultra-compact SWIR telephoto lens design

Abstract

Abstract:A new optical design strategy for rotational aspheres using very few parameters is presented. It consists of using the SMS method to design the aspheres embedded in a system with additional simpler surfaces (such as spheres, parabolas or other conics) and optimizing the free-parameters. Although the SMS surfaces are designed using only meridian rays, skew rays have proven to be well controlled within the optimization. In the end, the SMS surfaces are expanded using Forbes series and then a second optimization process is carried out with these SMS surfaces as a starting point. The method has been applied to a telephoto lens design in the SWIR band, achieving ultra-compact designs with an excellent performance.

Analytic free-form lens design for imaging applications with high aspect ratio

“…The exponents for y-coordinate take already into account that all functions are either even (provided by 2j) or odd (provided by 2j − 1) in y-direction. This symmetry follows immediately from the later introduced equations (10) and (11). The linear systems of equations for the correspondent Taylor series coefficients have null vectors as only possible solutions and are therefore discarded already in the Taylor series.…”

“…8 It offers the flexibility to choose the ray sets and their associated image points and design rotational symmetric optics for imaging applications. [9][10][11] Recent years have also seen a raising interest in free-form optics for off-axis imaging designs, as well as the extension of aberration theory in imaging systems without rotational symmetry.…”

“…The matrix elements of M x , M y and M xy consist of mathematical expressions which depend on Taylor series coefficients calculated for the initial conditions. The needed vector elements of b (n,m) are mathematical expressions only dependent on previously calculated Taylor series coefficients for o = 2, 3, .., (n + m − 1) and can be calculated for each ordinal number o = 2, 3, .. in ascending order and for all possible combinations of n and m from equations (9)- (11). For known matrices M x , M y and M xy and vectors b (n,m) , the Taylor series coefficients can be calculated by solving the linear systems of equations (12).…”

Design Method for a Total Internal Reflection LED Lens with Double Freeform Surfaces for Narrow and Uniform Illumination

“…The LED lens can be designed using a differential equation method [8][9][10][11], a parameter optimization method [12][13][14][15], or a simultaneous multiple surface (SMS) method [16][17][18], and it often includes one or more freeform surfaces, for the sake of low price and high efficiency. The differential equation method is an LED lens design method in which differential equations relating to the propagation of rays through an LED lens are solved assuming that one surface of the lens is already known; then the other surface is freeform.…”

“…In particular, the method entails a problem in that the number of the parameters increases with increasing complexity of the shape of an LED lens, thus making optimization difficult. Finally, in the SMS method, since all surfaces of an LED lens must be controlled to obtain the desired performance, much time is inevitably required to calculate a large amount of information about the lens surface [16][17][18].…”