星载离轴多光谱相机焦平面的装调与检测

针对某离轴多光谱相机焦平面高精度的装调要求,设计了焦平面组件,阐述了装调、检测的仪器设备和方法。首先将焦平面组件安装至镜头,测量并解算出CCD光敏面的角度和位移偏差,接着根据偏差确定调整垫修研量,进行初次修垫并重新安装,然后利用调整工装微调CCD姿态至满足指标要求,调整垫处打销钉定位,最后根据拟合出的最佳焦平面位置再次修研调整垫,利用销钉复位完成装调工作。检测结果表明,相机的CCD光敏面相对于设计焦平面三维角度偏差分别为Δα=-6.7″,Δβ=1.9',Δγ=13.2″,三维位移偏差分别为Δx=-0.004 mm,Δy=0.006 mm,Δz=-0.070 mm,相机四谱段、全视场MTF优于0.25,满足设计和装调要求。测量和解算误差分析表明,所用的设备与方法能够满足装调精度的要求,可以为此类相机的研制提供一定的技术参考。

Focal plane alignment and testing for an off-axis multispectral space borne camera

To meet the requirements of high alignment accuracy for a multispectral camera, a focal plane subassembly is designed. Meanwhile, the instruments, fixtures and methods for alignment and measurement are described. First of all, the focal plane subassembly is mounted to the optics so that deflections and shifts of the CCD photosensitive area related to the image plane could be measured and calculated. According to the results given previously, the removal dimension of adjustment spacers is determined and preliminary modification is applied to the spacers. Thereafter, the focal plane subassembly is remounted. Then, the CCD is fine adjusted to its correct orientation and location, and locating pins are embedded into the spacers to hold this adjustment. Finally, based on the fitted optimum focal plane position, spacers are carefully ground and restored. Thus, the alignment is completed. Test results show that, three-dimensional deflections are Δα=-6.7", Δβ=1.9' and Δγ=13.2" respectively; three-dimensional shifts are Δx=-0.004 mm, Δy=0.006 mm and Δz=-0.070 mm respectively. The Modulation Transfer Functions(MTF) corresponding to four spectra and whole field of view are more than 0.25, which can meet the design and alignment specifications. The measurement and calculation error analysis shows that the equipments and methods can meet the precision requirements and provide technique references for homologous cameras.