.In the field of the active wavefront correction for off-axis telescopes, the sensitivity matrix and damped least squares method are widely employed to calculate the misalignment. Improper selection of the damping coefficient will lead to bad wavefront correction results. Moreover, the calculated misalignment is referenced on the optical coordinate system, which cannot be directly applied as the control quantity. The article has two innovative points to solve these problems. First, an adaptive damping least squares method is proposed. The method considers the mirror surface error, uses Python + Zemax cosimulation to perform closed-loop reverse verification, and selects the optimal damping coefficient. Simulation is carried out for verification. Second, the article deduces the mathematical relationship between the calculated misalignment and the mechanism control quantity. Based on the above research, the wavefront active correction experiment has been completed. The optical component is actively adjusted with the wavefront quickly converging to RMS  =  0  .  055λ  @  632  .  8  nm. The results verify the correctness of the proposed method.

Coaxial transmission optical systems can be assembled by optical centering processing and optical centering assembly to eliminate the eccentricity and tilt of each lens, thus ensuring the coaxiality of the lens. Non-coaxial transmission optical systems cannot be assembled by the traditional optical centering method, and this type of system poses a new challenge to the assembly method. Aiming at a non-coaxial transmissive optical system, this paper proposes a precise assembly method based on the spatial coordinate change and the principle of self-collimation imaging. Firstly, we calculate the spatial angle and eccentricity value of different axis mirror groups, and then use two self-collimating theodolites and optical reticle centering tools to construct the spatial angle reference and eccentricity reference for different axis mirror groups. Then, the spatial position of each lens group is determined by the adjustment method of auto-collimation. The article finally carried out the alignment experiment. The wavefront RMS of the optical system after alignment is 0.026λ@632.8nm which meets the design requirements and verifies the effectiveness of the proposed method.

A five-mirror optical derotator system is used in the Accurate Infrared Magnetic System solar telescope by virtue of its polarization-free and superior real-time performance. The derotator system can compensate image rotation during tracking observation. The system consists of five flat mirrors with their normal vectors noncoplanar. Due to the complicated spatial positions of mirrors, it is challenging to align the system with high accuracy. We analyze parallelism and concentricity characteristic of derotator system by matrix transformation and propose a compensation alignment method from multivariables perturbation simulation. This method reduces degrees of freedom for alignment from 10 to 4, which greatly simplifies the installation and adjustment process. Based on the above simulation, the alignment experiment has been conducted successfully with the parallelism and concentricity meeting the requirements. Through theoretical analysis and experimental verification, the proposed method is reasonable and provides an efficient alignment solution for this kind of five-mirror optical derotator system.

In this paper, the assembly and rectification method of the new optical system is studied. According to the characteristics and difficulties of the diffraction camera, the assembly and rectification scheme is formulated. Firstly, the space angle of the mirror is determined by the spatial attitude measurement and the reference conversion matrix method. The coaxial adjustment and combined detection and adjustment of each transmission lens group are completed by the self alignment method. The method of sensitivity matrix iterative fine adjustment based on aberration is applied in the whole machine assembly and adjustment process. Finally, the high-precision assembly and detection of the complex offset axis infrared diffraction camera were completed, and the wave aberration on the axis reached 0.119λ@3.39μm. The MTF reached 0.13@33lp/mm, meeting the design requirements. This method provides engineering experience and reference for similar camera assembly and adjustment process methods.

No abstract