We present an analytical design method for the three-mirror anastigmatic (TMA) telescope with mirror spacings as the free design parameter. After the optical designer determines, the system focal length and the mirror spacings according to the design requirements, the design solutions of all TMA telescopes that meet the conditions can be obtained directly according to the formulas for the mirror radius and conic constants derived. The method here can predetermine the mirror position and system envelope size before design, and can quickly give all design solutions. We give a design example using the method and compare and discuss all design solutions of TMA.
In order to meet the requirement of miniaturization, high image quality and large field of view of monitor lens, based on the characteristics of monocentric lenses, and the development of curved image sensors, we designed a monitor lens optical system and all refraction surfaces and its curved image surface have the same spherical center. The monitoring optical system's FOV is 140°, the focal length is 7.88mm, the F-number is 1.50, and the total length is 14.47 mm. The monitoring optical system is up to 11-megapixel. The final design result shows that the MTF value is closed to the diffraction limit in the central field of view and the 0.7 field of view, and is greater than 0.59 at all fields of view. The RMS radiuses of different fields of view are all less than 1.1 μm . It can be clearly seen that the aberrations of each field of view are well controlled from the quantitative analysis of the transverse ray fan plot. The monitor lens has good performance in quite a large FOV with a miniaturization structure.
Star sensor is a high accuracy sensitive instrument for attitude determination, and the optical system is an essential part of the star sensor. According to the user requirements and CODE V patent library, the optical lens of a star sensor with large relative aperture and wide-spectrum range is optimized. The final design consists of 8 spherical lenses. The focal length is 50mm, the relative aperture is 1/1.35, the field of view is 7° × 7° (the diagonal field is 9.9°), and the spectral range is 500nm to 800nm. The design results show the optical lens has good performance. The distortion is less than 1%, the energy concentration is more than 80%, and the MTF of all fields of view is close to each other. The energy concentration of the spot diagram on the off-axis field of view and the on-axis field of view remains basically the same. The optical system meets modern design requirements for the star sensors.
In order to meet the requirement of high image quality and super-wide-angle mobile phone lens, a super-wide-angle mobile phone lens with a curved image surface and 10 megapixels based on monocentric lenses is designed in the paper. The mobile phone lens is composed of 4 monocentric lenses. The focal length is 3.32mm, the F-number is 1.85, the FOV is 95° and the total length is 5.24mm. The final design shows that the MTF is larger than 0.52 in the 0.7 field of view and the MTF of the whole FOV is larger than 0.45 at 209 lp/mm. The MTF is larger than 0.3 in the 0.7 field of view and the MTF of the whole FOV is larger than 0.2 at 417 lp/mm. The RMS radiuses of different fields of view are less than 3 μm . The relative illumination values are greater than 0.6 in the full field of view. The optical system has good image quality.
Active optics usually uses the computation models based on numerical methods to correct misalignments and figure errors at present. These methods can hardly lead to any insight into the aberration field dependencies that arise in the presence of the misalignments. An analytical alignment model based on third-order nodal aberration theory is presented for this problem, which can be utilized to compute the primary mirror astigmatic figure error and misalignments for two-mirror telescopes. Alignment simulations are conducted for an R-C telescope based on this analytical alignment model. It is shown that in the absence of wavefront measurement errors, wavefront measurements at only two field points are enough, and the correction process can be completed with only one alignment action. In the presence of wavefront measurement errors, increasing the number of field points for wavefront measurements can enhance the robustness of the alignment model. Monte Carlo simulation shows that, when −2 mm ≤ linear misalignment ≤ 2 mm, −0.1 deg ≤ angular misalignment ≤ 0.1 deg, and −0.2 λ ≤ astigmatism figure error (expressed as fringe Zernike coefficients C5 / C6, λ = 632.8 nm) ≤0.2 λ, the misaligned systems can be corrected to be close to nominal state without wavefront testing error. In addition, the root mean square deviation of RMS wavefront error of all the misaligned samples after being corrected is linearly related to wavefront testing error.