The invention relates to a trace substance analysis device based on near-field optical traveling-
wave absorption. The prior art has a complex structure and high optical
machine requirement, and fails to obtain high-precision spectral information. The device comprises an annular high-
fineness cavity consisting of a single optical element, namely an isosceles
triangular prism, and two equicrural surfaces are high-
reflectivity surfaces; a
light beam is incident from one high-
reflectivity equicrural surface, performs the
total internal reflection on the bottom surface of the
prism to form a near-field
optical test area, forms optical traveling-wave in the isosceles
triangular prism, and emerges from another high-
reflectivity equicrural surface; the emergent
light beam passes through a high-precision light splitting unit of an Fabry-Perot cavity consisting of two high reflection mirrors, and a moving part drives one high reflection mirror of the Fabry-Perot cavity to move along the axial direction to adjust and control emergent spectral information; and a photoelectric
detector receives an emergent beam from the Fabry-Perot cavity, forms a high-precision spectrum
signal, and realizes the detection of trace substances. The device has the characteristics of simple and steady
system structure, high precision of spectral information, less quantity of needed detected substances, broad applicable range and the like.