Reflective filtering module and filtering method thereof

Abstract

The invention provides a reflective filtering module and a filtering method thereof. The reflective filtering module comprises at least two optical filters, wherein the wavelength of to-be-emitted light in a mixed light beam is located in the reflection wave band of each optical filter, the to-be-emitted light is reflected at least twice between the optical filters, the wavelength of the to-be-filtered light in the mixed light beam is located in the transmission wave band of each light filter, so that the to-be-filtered light is transmitted between the light filters for at least two times; and the mixed light beam forms a first reflected light beam after being reflected for the first time, and forms an emergent light beam which does not coincide with the first reflected light beam after being reflected for the last time. According to the reflective filtering module, the effect of a short-wave-pass optical filter can be realized when a long-wave-pass optical filter is used, and the effect of a long-wave-pass optical filter can be realized when the short-wave-pass optical filter is used. The to-be-emitted light is emitted from the reflective filtering module with extremely high reflectivity and is not influenced by the fluctuation of the transmittance of the optical filter, so that the noise of a spectral signal is reduced, and a signal-to-noise ratio of a spectral signal is improved.

Description

technical field [0001] The invention relates to the technical field of filter devices, in particular to a reflective filter module and a filter method thereof. Background technique [0002] In spectral applications, in order to detect useful signals, it is necessary to use specific filters to filter out unwanted light. In current applications, the light to be filtered is usually reflected by a filter with a high OD (Optical Density, optical density) value, so that the light to be emitted passes through the filter and is finally collected by a detector. At present, regardless of the short-pass filter or the long-pass filter, high OD values ​​can be achieved in the reflection band, but the transmittance is not constant in the transmission band. Such as Figure 1a with Figure 1b As shown, the dotted line is the transmittance curve of the short-wave pass filter, and the solid line is the transmittance curve of the long-wave pass filter. Whether it is a short-wave pass filter ...

AI Technical Summary

Problems solved by technology

Therefore, in the current application, although the light to be filtered can be filtered with a higher OD value, the collected signal will always be affected by the fluctuation of the transmittance of the filter itself, and noise glitches will appear in the spectral signal , affecting the signal-to-noise ratio of the spectral signal, this phenomenon will cover up the useful information in the spectrum when the outgoing light is very weak

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