The frequency of a Lidar signal is measured in:

The measurement of Lidar signal frequency in terahertz is accurate because Lidar operates using laser light, which typically falls within the infrared to visible spectrum. The frequencies of electromagnetic waves, including light, are extremely high compared to radio waves or sound waves.

Lidar systems usually emit light at wavelengths ranging from approximately 700 nanometers to 1550 nanometers, which correspond to frequencies in the terahertz range. For example, the frequency of light at 800 nanometers is about 375 terahertz. This high frequency is essential for the Lidar systems to achieve the resolution and accuracy necessary for distance measurement and object detection.

Choosing terahertz correctly reflects the technology's underlying physics, as this frequency range is specifically where optical and infrared light operates. Other options, like gigahertz, megahertz, or kilohertz, relate to lower frequency signals typically used in other areas of communication or technology, such as radio signals, and are not relevant to the operation of Lidar.