Opt Lett. 2018 Oct 15;43(20):5050-5053. doi: 10.1364/OL.43.005050.
We present an image upconversion system based on intracavity Type II second-harmonic generation to create an image in the visible spectrum of a target illuminated by an infrared laser. The system has the novelty of being self-illuminated. It uses some fractional leaking power of the infrared laser to illuminate a target located in the object focal plane of the system, and to couple back a created infrared target image to an intracavity nonlinear crystal, where it mixes with the cavity laser beam to obtain a second-harmonic image, visible with a silicon CCD camera. For a proof of concept, we have built a system based on a diode-pumped Nd:YVO continuous-wave (cw) laser and an intracavity KTP crystal to upconvert 1342 nm target images to 671 nm. The upconverted cw power allowed us to capture real-time video in a standard nonintensified CCD camera, with 2.5 W of a diode pump.
我们提出了一种基于腔内 II 型二次谐波产生的上转换系统，以在目标被红外激光照明时在可见光谱中创建图像。该系统的新颖之处在于它是自照明的。它利用红外激光的一些分数泄漏功率来照明位于系统物方焦平面上的目标，并将创建的红外目标图像耦合回到腔内非线性晶体中，在那里与腔激光束混合以获得二次谐波图像，用硅 CCD 相机可见。为了验证概念，我们已经建立了一个基于二极管泵浦 Nd:YVO 连续波（cw）激光和腔内 KTP 晶体的系统，将 1342nm 的目标图像上转换为 671nm。上转换的 cw 功率允许我们在标准非增强型 CCD 相机中以 2.5W 的二极管泵浦实时捕获视频。
