1. Reminders

1.1 General concept

Lidar is an active optical remote sensing analysis method, as it uses its own laser light source to probe the atmosphere. Lidar differs from passive radiometric remote sensing methods, which use scattered sunlight (UV to near-IR) or IR radiation emitted by the atmosphere. The example of ordinary photography, with or without a flash of light, is a good illustration of the distinction between active and passive. The laser light source can also be used for measurements in the absence of sunlight: at night, in winter, for example.

Readers are invited to consult general works on lidars