Absorption cavity type laser breakdown detection device

The invention discloses an absorption cavity type laser breakdown detection device which comprises an absorption cavity, an excitation light source, a detection light source, an acousto-optic modulation device, a light detector and an electronic control system for controlling the working process. According to the absorption cavity type laser breakdown detection device, a laser-induced breakdown technology and a light ring-down technology are combined; a sample to be detected is placed in a ring-down cavity; excitation light is focused and enters to the sample to be detected; under heat absorption, a nano particle cloud cluster is formed by the sample to be detected and is dispersed into the cavity; the detection light is reflected back and forth between high-reflectivity mirrors at the two ends of the ring-down cavity and is continuously absorbed by corresponding substances; the detector outside the cavity is used for detecting an emergent signal, so that the content of the substances can be calculated. By combination of the laser induced breakdown and light ring-down technologies, by use of the high-reflectivity mirrors, the detection extreme can be ppb level; before excitation light irradiation, the absorption cavity is vacuumized, so that interference of other components in air can be prevented, and widening of a spectral line can be reduced; therefore, the detected spectral line is easy to distinguish, and the flexibility is improved.