the light source unit is configured for coupling and then outputting first light source light of a plurality of first light sources with different wavelength ranges capable of imaging at night, wherein the light source unit comprises a constant current power supply, the plurality of first light sources with different wavelength ranges, a plurality of couplers corresponding to each of the plurality of first light sources, and a one-into-many optical fiber; and each first light source emits the first light source light based on electrical energy provided by the constant current power supply, and the first light source light is coupled to a receiving end of the one-into-many optical fiber through the corresponding coupler, and the first light source light of all the first light sources is transmitted through the one-into-many optical fiber and outputted from an emergent end of the one-into-many optical fiber;

the detection light path unit is configured for collimating and then outputting the first light source light emitted by the light source unit, and receiving remote sensing light fed back based on the first light source light, wherein the detection light path unit comprises an emergent coupling lens, a semi-transparent and semi-reflective prism, and a collimating telescope subsystem, the first light source light emitted by the light source unit passes through the emergent coupling lens, the semi-transparent and semi-reflective prism and the collimating telescope subsystem sequentially to be collimated, and a collimated light beam is irradiated on a corner reflector in the unmanned aerial vehicle tracking light path unit to form an emergent light path for gas measurement, wherein the surface precision of the emergent coupling lens is less than a quarter of a wavelength based on 200 nm, and the emergent coupling lens is located at a focus of a first reflector at a distance from the first reflector at an incident end of the collimating telescope subsystem, to determine a position of an emergent end of the one-into-many optical fiber so that an optical fiber emission angle passing through the emergent coupling lens is less than 30°;

wherein an unmanned aerial vehicle also carries the corner reflector, wherein emergent light of the detection light path unit, after being transmitted in a measurement area, carries information of the multi-component atmospheric trace constituents and is received and then reflected by the corner reflector, reflected light is received by the collimating telescope subsystem, and then passes through the semi-transparent and semi-reflective prism, the emergent coupling lens and the output end of the one-into-many optical fiber sequentially to form a collection light path for gas measurement;

the unmanned aerial vehicle tracking light path unit is configured for tracking and positioning the unmanned aerial vehicle based on the unmanned aerial vehicle tracking light path, wherein the unmanned aerial vehicle tracking light path unit comprises the unmanned aerial vehicle carrying two second light sources, a reticle, an eyepiece, and a charge coupled device (CCD) detector; and

emergent light of the second light sources is received by the collimating telescope subsystem and irradiated on the semi-transparent and semi-reflective prism, after being reflected by the semi-transparent and semi-reflective prism, the incident light is emitted to the CCD detector through the reticle and the eyepiece, the CCD detector detects positions of two second light source imaging points on the reticle to form the unmanned aerial vehicle tracking light path, the unmanned aerial vehicle tracking light path is coaxial with a detection light path through the semi-transparent and semi-reflective prism, and the CCD detector generates a deviation correcting signal when the two second light source imaging points move; and

the control and processing unit is configured for collecting an original spectrum of the first light source light and a remote sensing spectrum of the remote sensing light and performing imaging analysis and processing on the multi-component atmospheric trace constituents, and is also configured for adjusting and controlling the unmanned aerial vehicle tracking light path based on tracking and positioning information.