In robotics, LIDAR and RADAR are both used for obstacle detection. The data they produce are very similar, but they do have different qualities (LIDAR is more precise but less robust). There are many websites that tell me that the difference between RADAR and LIDAR is that one uses radio waves while the other uses light.
But both of these are electromagnetic waves, so why aren't they the same technology? As far as I'm able to figure out so far, RADAR uses antennae and works on waves no smaller than a millimeter, while LIDAR uses photodetectors of some kind and works in infrared (smaller than a micrometer).
Why can't LIDAR be implemented with traditional antennae? Is the wavelength too short to be detected by current electronics? Or is it due to interference with the sun at higher frequencies? Or maybe higher frequencies don't bounce off objects in quite the same way?
(Btw, my understanding of a "traditional antenna" is that the EM waves induce current in a wire, and the receiver somehow filters out all but a particular wavelength.)