Optical method for detecting toxic substances based on time flight method

The invention discloses an optical method for detecting toxic substances based on a time flight method; wherein a medium-wave-band optical fiber polarization laser and a short-wave-band optical fiber polarization laser emit polarized laser to form two beams of light curtains with the same thickness, and the short-wave-band laser in the two beams of light curtains can excite fluorescence, meanwhile the middle wave band can generate scattered light; then the avalanche diode photoelectric detector can detect all optical signals in the two wave bands, fluorescence is detected by the avalanche diode under the action of the optical filter, and the substance is recorded as a toxic substance. Therefore, by combining the calculated aerodynamic diameter, the aerodynamic particle size and content of the toxic substances can be obtained. The method has the advantages that the structure is simple, required optical devices is few, and the optical structure is simple.The method can be combined with a time flight method to t