Fiber grating demodulation system for enhancing spectral resolution by finely shifting slit

A fiber grating demodulation system for enhancing spectral resolution by finely adjusting a slit, the demodulation system comprising a laser pump source, a wavelength division multiplexer, a fiber Bragg grating, a diaphragm, a slit, a collimating mirror, a light splitting grating, an imaging focus mirror, a linear array detector and a processor, wherein

• the laser pump source, the wavelength division multiplexer, and the fiber Bragg grating are connected in sequence, and the wavelength division multiplexer is further connected to the diaphragm;
• light emitted from the laser pump source is multiplexed by the wavelength division multiplexer and then enters the fiber Bragg grating, and a reflection spectrum of the fiber Bragg grating enters the slit of the fiber grating demodulation system as injected light, and after passing through the slit, the injected light is reflected by the collimating mirror, the light splitting grating, and the imaging focus mirror in sequence, and is finally converged to the linear array detector;
• and
• the slit is configured to shift along a direction perpendicular to incident direction of the light within a certain range in order to change an incident direction of the light, so as to obtain finer interference stripes at smaller intervals on the linear array detector,
• wherein the adjustment of the shifting distance of the slit is implemented by the processor in following steps:
• a) adjusting the piezoelectric execution element to a lowest end, a current voltage being recorded as an initial adjusted voltage;
• b) recording spectrum data at the lowest end as an initial spectrum;
• c) adjusting the piezoelectric execution element at a small step length, and calculating a current spectrum and the initial spectrum, wherein the piezoelectric execution element is a position servo, and a position instruction is inputted to control the slit to shift by a small step of distance, so as to adjust a spatial position of incident light and determine a spectrum imaging position, a correlativity is calculated and recorded accordingly;
• d) recording an adjusted voltage obtained when the correlativity reaches a peak value for the first time, as a final adjusted voltage;
• and
• e) equally dividing an interval between the initial adjusted voltage and the final adjusted voltage into a plurality of levels, and performing measurement for each level during each demodulation, so as to obtain a higher spectrum spatial resolution.