In light science and applications, equally important roles are played by efficient light emitters/detectors and by the optical elements responsible for light extraction and delivery. The latter should be simple, cost effective, broadband, versatile and compatible with other components of widely desired micro-optical systems. Ideally, they should also operate without high-numerical-aperture optics. Here, we demonstrate that all these requirements can be met with elliptical microlenses 3D printed on top of light emitters. Importantly, the microlenses we propose readily form the collected light into an ultra-low divergence beam (half-angle divergence below 1°) perfectly suited for ultra-long-working-distance optical measurements (600 mm with a 1-inch collection lens), which are not accessible to date with other spectroscopic techniques. Our microlenses can be fabricated on a wide variety of samples, including semiconductor quantum dots and fragile van der Waals heterostructures made of novel two-dimensional materials, such as monolayer and few-layer transition metal dichalcogenides.

在光科学和应用中，高效的发光器/检测器以及负责光的提取和传输的光学元件都扮演着同等重要的角色。后者应该是简单的，具有成本效益的，宽带的，通用的并且与广泛期望的微光学系统的其他组件兼容。理想情况下，它们也应在没有高数值孔径光学器件的情况下工作。在这里，我们证明了通过在发光器顶部打印的椭圆形微透镜3D可以满足所有这些要求。重要的是，我们建议使用微透镜将收集的光轻松地形成超低发散光束（半角发散度低于1°），非常适合超长工作距离光学测量（1英寸收集透镜为600毫米） ，这是其他光谱技术迄今为止无法获得的。