Refractive index sensor and detection method thereof

Abstract

The invention discloses a refractive index sensor and a detection method thereof. The refractive index sensor provided by the invention comprises an exciting device and a measuring device, wherein the exciting device comprises a monochromatic light source, a focusing device and a sensor chip; the measuring device is composed of a leakage radiation microscope system comprising an oil immersion objective, an imaging lens and a CCD (Charge Coupled Device) camera; the light emitted by the monochromatic light source is incident to the sensor chip via the focusing device to excite a surface plasma excimer SP; the leakage radiation light of the SP is collected by the oil immersion objective and is incident to the CCD camera together with the other beam of reference light after passing through the imaging lens, so as to cause interference at the CCD camera; the CCD camera records the information of interferometric fringes; and the refractive index of a sample to be measured on the upper surface of a metal thin film is monitored according to the cycle of the interferometric fringes. The refractive index sensor has the advantages that only a wavelength light source is needed, the structure is simple and the cost is low; the measurement is not sensitive to the intensity fluctuation of an incident light source and the noise of a detector; the accuracy of the data measurement is improved; and the microminiaturization and multi-channel detection of the sensor can be realized.

Description

technical field [0001] The invention relates to the technical field of optical measurement, in particular to a refractive index sensor based on the interference effect of surface plasmons and reference light and a detection method thereof. Background technique [0002] Surface plasmon SP (Surface Plasmon) is an electromagnetic mode that is localized on the metal / dielectric interface and propagates along the metal surface. The electromagnetic field strength decays exponentially in the direction perpendicular to the metal surface; and the surface plasmon The wavenumber along the direction of propagation is greater than the wavenumber of a photon propagating freely in this medium at the same frequency. Usually, there is no direct conversion between light and surface plasmons, and nanostructures or special configurations need to be introduced to meet the wave vector matching conditions. The coupling between light and surface plasmons is very sensitive to the refractive index of...

AI Technical Summary

Problems solved by technology

The existing SPR sensors mainly have the following problems: 1) The SPR refractive index sensing scheme uses a spectral detection method, which requires a relatively expensive spectrometer and a broadband light source; The intensity fluctuation of the light source and the noise sensitivity of the detector; 3) The traditional refractive index sensor (such as the prism-type SPR sensor) monitors the change of a certain peak or valley, and the data measurement is not accurate enough; 4) The size of the sensor is large, which is not conducive to integration

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