This work proposes a novel scheme for a back focal plane (BFP)-type apertometer. The basic concept is to generate “multi-references” on BFP via the grating projection, which shows superiorities in two aspects: (1) a wider measurement range for both dry and immersion objectives; (2) higher accuracy via self-calibration of multi-references. To the best of our knowledge, this is the first approach and setup to allow the measurement of objectives with NA across unity via a “virtual” Fourier plane. It is also the first time to demonstrate a self-calibrated BFP-type apertometer with multi-references. All the involved concepts are experimentally verified.

中文翻译：

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通过光栅投影参考，用于干透镜和浸没透镜的自校准 BFP 型孔径计

这项工作提出了一种用于后焦平面 (BFP) 型孔径计的新方案。基本概念是通过光栅投影在 BFP 上产生“多参考”，其优势体现在两个方面：（1）干物镜和浸没物镜的测量范围更广；(2) 通过多参考的自校准获得更高的精度。据我们所知，这是第一种允许通过“虚拟”傅立叶平面使用 NA 跨单位测量目标的方法和设置。这也是第一次展示具有多参考值的自校准BFP型孔径计。所有涉及的概念都经过实验验证。