"Due to design limitations imposed by the two surfaces of identical radius of curvature, the former has noticeably inferior off-axis performance: at 0.5° off-axis the wavefront error (best surface) is 0.24 wave RMS, mostly due to the coma, but also astigmatism."
只是基本的对比,实际的两片式曲率半径应该会做优化。两片式的我更想看看Questar的。
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