Photocoupler
This circuit is described in the latest version of an amateur radio magazine. Its operation allows for any mode up to 1 watt (license free) in the 160 to 190 kHz band (CW/SSB/FM). It consists of a receive converter from 5 kHz to 450 kHz and a transmit converter that converts 3.66 to 3.69 megahertz (80 m) to 160 to 190 kHz.
Meniscus lenses are divided into positive meniscus and negative meniscus lenses. A meniscus lens has one side of the lens that is convex and one side that is concave. It can be a converging lens or a diverging lens, determined by the refractive index, curvature and radius together. Widely used in photographic systems, projection systems, imaging systems, optical viewfinders, and laser measurement systems.
Meniscus Lens,Concave-Convex Lens,Optical Meniscus Lens,Meniscus Diverging Lens
Changchun Realpoo Photoelectric Co., Ltd. , https://www.optics-realpoo.com