Highly compact optical design of an off-axis three-mirror system with freeform surfaces

Abstract This paper discusses the accommodative relaxation of myopic adults by using a simple double-mirror design. This optical design can extend the viewing distance to 2.285 m and magnify the image up to 3.79 times, and it results in the accommodative relaxation of a single human eye. We recruited 32 subjects with an average age of 20.8 ± 0.95 years old. After an examination of their refractive status, the disposable contact lenses with a corresponding refractive error were corrected, and the dynamic accommodative response and the change in pupil size were measured by using an open-field auto-refractor. The dynamic accommodative responses and pupil size data were collected under two viewing distance conditions. When the subjects gazed at a real object that was 0.4 m away, or a virtual image that was 2.285 m away, the mean value of the accommodative response was 1.69 ± 0.31D or 0.11 ± 0.05D, and the pupil size was 3.79 ± 0.49 mm or 4.09 ± 0.72 mm, respectively. The accommodative response decreased and the pupil size increased by using the double-mirror system, and therefore, accommodative relaxation can be achieved by using this new optical design. In this study, we first successfully proposed a simple optical design to relax the accommodation, and the fluctuations of the accommodation response were stable, with the extended viewing distance of 2.285 m. This design may be applied for the improvement of visual function, such as the reduction of asthenopia and the control of myopia.

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Active Optics in Astronomy: Freeform Mirror for the MESSIER Telescope Proposal

Mathematical and Computational Applications ◽

10.3390/mca24010002 ◽

2018 ◽

Vol 24 (1) ◽

pp. 2 ◽

Cited By ~ 1

Author(s):

Gerard Lemaitre ◽

Pascal Vola ◽

Eduard Muslimov

Keyword(s):

Optical Design ◽

Field Of View ◽

Wide Field ◽

Uniform Load ◽

Freeform Surfaces ◽

Aspheric Surfaces ◽

Active Optics ◽

Aspheric Mirror ◽

Minimum Number ◽

Drift Scan

Active optics techniques in astronomy provide high imaging quality. This paper is dedicated to highly deformable active optics that can generate non-axisymmetric aspheric surfaces—or freeform surfaces—by use of a minimum number of actuators. The aspheric mirror is obtained from a single uniform load that acts over the surface of a closed-form substrate whilst under axial reaction to its elliptical perimeter ring during spherical polishing. MESSIER space proposal is a wide-field low-central-obstruction folded-two-mirror-anastigmat or here called briefly three-mirror-anastigmat (TMA) telescope. The optical design is a folded reflective Schmidt. Basic telescope features are 36 cm aperture, f/2.5, with 1.6° × 2.6° field of view and a curved field detector allowing null distortion aberration for drift-scan observations. The freeform mirror is generated by spherical stress polishing that provides super-polished freeform surfaces after elastic relaxation. Preliminary analysis required use of the optics theory of 3rd-order aberrations and elasticity theory of thin elliptical plates. Final cross-optimizations were carried out with Zemax raytracing code and Nastran FEA elasticity code in order to determine the complete geometry of a glass ceramic Zerodur deformable substrate.

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Asphericity and Discrete Phase Calculation for Optical Freeform Surface Test with Computer Generated Holograms

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.718-720.1797 ◽

2013 ◽

Vol 718-720 ◽

pp. 1797-1803

Author(s):

Ya Huang ◽

Ri Hong Zhu ◽

Jun Ma ◽

Hua Shen

Keyword(s):

Ray Tracing ◽

Phase Distribution ◽

Rotational Symmetry ◽

Optical Design ◽

Freeform Surface ◽

Freeform Surfaces ◽

Maximum Angle ◽

Phase Calculation ◽

Discrete Phase ◽

Computer Generated Holograms

Optical freeform surfaces are complex surfaces with non-rotational symmetry that break through the limitations of conventional optical element, and are widely used in advanced optics application for system configuration simplifying and performance enhancing. Interferometric test with computer generated holograms (CGH) has been widely used in the aspherical surfaces testing for their unique wavefront transformation, as well as the freeform surfaces testing with high precision. As an important parameter, it is different at the definition of asphericity in freeform surfaces manufacture and test. Asphericity for interferometric test which verifies the testing ability of the CGH and determines testing system initial configuration was calculated with minimum maximum angle deviation. Reverse ray tracing could get the optimal solution of CGH local phase at certain location in the CGH design. For the non-rotational symmetry of freeform surfaces, the phase of sample point in CGH surface should be calculated in three-dimensional coordinate system. The calculation method of discrete phase was deduced by ray tracing, as well as the phase distribution on freeform surface were proven by calculating in such way. The results were compared with simulation by optical design software. It shows that the method is right and high accuracy to be used in the CGH design for the freeform surfaces.

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