Research on detecting the position of LAMOST field’s fiber units

Zhigang, 刘志刚 Liu; Pu, 黄璞 Huang; Junfeng, 吴俊丰 Wu

doi:10.3788/gxjs20123802.0166

Cited by 2 publications

(4 citation statements)

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“…In the LAMOST system, the diameter of the emitting end face of each fiber is only 0.32 mm, and the diameter of the corresponding imaging spot is only a few pixels. In this case, the optical center of gravity algorithm offers good accuracy in representing the positions of the light spots and can generally achieve an accuracy of ∼0.06 pixels 19 , 20 …”

Section: Algorithms For Obtaining Fiducial Fiber Positionsmentioning

confidence: 99%

“…The LAMOST project team has carried out a relatively mature study on the calibration algorithm for the photographic system and has determined a stable and reliable camera correction model. 4 The next problem that needs to be solved is how to obtain accurate measurements of the spatial positions of the fiducial fibers to serve as a benchmark. Generally, camera calibration requires determining the geometric and optical characteristic parameters inside a camera and the position and direction of the camera in the three-dimensional spatial coordinate system, that is, the internal and external camera parameters, to obtain the relationship between the image plane coordinate system and the world coordinate system.…”

Section: Introductionmentioning

confidence: 99%

“…The imaging accuracy must be guaranteed through two approaches: one is to select a suitable calibration model, and the other is to guarantee the benchmark measurement accuracy. The LAMOST project team has carried out a relatively mature study on the calibration algorithm for the photographic system and has determined a stable and reliable camera correction model 4 . The next problem that needs to be solved is how to obtain accurate measurements of the spatial positions of the fiducial fibers to serve as a benchmark.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation method to obtain a fiducial fiber metrology benchmark for the Large Sky Area Multi-Object Fiber Spectroscopic Telescope

Liu,

Du,

Wang

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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.Realizing accurate positioning with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) closed-loop system depends on accurate high-precision calibration of the visual measurement system, which has a great impact on collision avoidance and accurate positioning. We designed fiducial fibers for the calibration of the LAMOST closed-loop system to provide accurate fiducial positions for visual measurement. The benchmark position accuracy of the fiducial fibers is a key factor affecting the accuracy of the visual measurement system; the more accurate the fiducial fiber positions are, the higher the visual measurement correction accuracy. In this study, three measurement methods were used to obtain the fiducial fiber positions, namely, measuring the hole positions using a coordinate measuring machine, imaging the fiducial fibers using a calibrated photographic system, and directly measuring the fiducial fiber spatial positions using a laser tracker. By evaluating the fiber positions obtained via the three methods, we can obtain a stable and reliable fiducial fiber position benchmark. A fiducial fiber positions evaluation method based on an optimal residual criterion is proposed, and the optimal residual solution for a small calibration target (SCT) is used to evaluate the optimal fiducial fiber measurement method. Specifically, the fiducial positions obtained via each of the three methods are used to invert the camera calibration parameters, which are then used to calculate the physical position of an SCT. Finally, the residual value between the calculated and theoretical positions is taken as the standard for evaluating the fiducial fiber measurement benchmark performance. The results show that the fiducial fiber positions measured using the laser tracker can be applied to effectively calibrate the photographic system, enabling the LAMOST vision measurement system to achieve a positioning accuracy of nearly 10 μm with the camera 20 m from the focal surface, whereas the accuracy is within 20 μm for ∼95 % of the measurement points.

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Section: Algorithms For Obtaining Fiducial Fiber Positionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation method to obtain a fiducial fiber metrology benchmark for the Large Sky Area Multi-Object Fiber Spectroscopic Telescope

Liu,

Du,

Wang

et al. 2023

J. Astron. Telesc. Instrum. Syst.

View full text Add to dashboard Cite

show abstract

“…Consequently, the problem of positioning the fibers becomes the localization of the centers of these spots. For light spots conforming to Gaussian distribution, common methods to determine their centroids include Gaussian model-based detection methods [6][7] , cross-projection-based algorithms [8] , and connected-domain-based centroid detection algorithms [9] . Although the Gaussian model-based centroid detection algorithm exhibits excellent accuracy, its computation is inefficiency making it challenging for practical engineering applications.…”

Section: Introductionmentioning

confidence: 99%