论文标题
自由形式的宽带扁平镜片可见成像
Free-form broadband flat lenses for visible imaging
论文作者
论文摘要
在没有单独的孔径的情况下，镜头的大小和焦距决定了其分辨率和光接收能力分别由数值孔径（NA）和F/＃定义。我们利用自由形式的宽带 - 伸缩元素（BDOES）来创建扁平镜头，使Na与F＃解脱，从而可以从其光收集能力独立选择镜头的分辨率。具体而言，我们设计，制造和表征了三个在可见频带（450nm-750nm）中运行的BDOE镜头，每个BDOE镜头分别为f/11.25，但NAS分别为0.00075、0.0067和0.054。模拟证实，即使在更高的NAS中，这种脱钩也是可能的。实验证实了具有色素聚焦和宽带成像。其中一个镜头显示出比衍射极限大的焦点近2个数量级。这种BDOE镜头在具有较大像素尺寸的焦距阵列中可能非常有用，需要维护光收集效率。此外，通过放弃旋转对称性，可以在焦点中实现自由形式的几何形状，例如正方形，可以更紧密地匹配传感器像素的几何形状。
In the absence of separate apertures, the size and focal length of a lens determines both its resolution and light-collection ability defined by numerical-aperture (NA) and f/#, respectively. We utilize free-form broadband-diffractive-optical elements (BDOEs) to create flat lenses that decouple NA from f#, whereby the resolution of the lens may be chosen independently from its light-collection ability. Specifically, we designed, fabricated and characterized three BDOE lenses operating in the visible band (450nm-750nm), each with f/11.25, but with NAs of 0.00075, 0.0067 and 0.054, respectively. Simulations confirm that such decoupling is possible even at much higher NAs. Experiments confirm achromatic focusing and broadband imaging. One of the lenses exhibited a depth-of-focus almost 2 orders of magnitude larger than the diffraction limit. Such BDOE lenses could be very useful in focal-plane arrays with large pixel sizes, where light collection efficiency needs to be maintained. Furthermore, by abandoning rotational symmetry, one can achieve free-form geometries in the focal spot, such as a square that can more closely match the geometry of the sensor pixel.
