laser

It consists of working medium, resonant cavity and excitation source. Under the action of the excitation source, the number of particles in the working substance is reversed, and through the oscillation and amplification in the resonant cavity, a positive feedback chain reaction is generated, thus emitting light with the same frequency, direction, polarization state and phase, which is laser. Laser is composed of countless photons, which is itself an electromagnetic wave.

radio frequency

It is a very important part of the electromagnetic spectrum. The energy of radio and microwave belongs to the category of electromagnetic radiation energy, commonly known as radio frequency. Radio frequency is based on frequency, and the range can be extended from several hundred kHZ to several hundred MHZ.

supersonic

This is a mechanical wave. The frequency of sound waves that the human ear can hear is 20 ~ 20000Hz. When the vibration frequency of sound waves is greater than 20000Hz, the human ear can't hear them. Ultrasound is named because its lower frequency limit is about equal to the upper hearing limit of human beings. So we call the sound wave with frequency higher than 20000Hz "ultrasonic wave".