Microscopic Raman system with continuously adjustable wavelength based on rotary optical filter

Abstract

The invention discloses a microscopic Raman system with continuously adjustable wavelength based on a rotary optical filter, and relates to the field of resonance Raman. The system is provided with a wavelength continuously adjustable laser, a reflecting mirror, an optical filter, a rotary table, an achromatic condensing lens and a spectrograph, the laser emitted by the wavelength continuously adjustable laser sequentially enters the reflecting mirror and the optical filter on the rotary table, then is introduced into the objective lens in a microscope, and is focused on a sample to be detected through the objective lens; scattered light on the sample to be detected is collected by the objective lens and then returns along the same path as a collimated light beam, laser Rayleigh lines are filtered out by the optical filter, and then the scattered light is focused into the spectrograph through the achromatic condensing lens. A special optical path system in which the reflecting mirror and the optical filter are integrally linked is utilized, the effect that an optical path is fixed while an optical element is rotated is achieved, when the optical filter rotates, the directions of two light beams of introduced laser and led-out signal light are constant, and the wavelength-tunable long-wave-pass optical filter can be applied to introduction of laser and leading-out of Raman signal light at the same time. The excitation wavelength is continuously adjustable; and the optical loss is extremely low.

Description

technical field [0001] The invention relates to the field of resonance Raman, in particular to a novel micro-Raman system with continuously adjustable excitation wavelength and continuously adjustable wavelength based on a rotary filter. Background technique [0002] Since the probability of occurrence of Raman scattering in most samples is small and the signal is weak, it is usually 10% of Rayleigh scattering. -3 -10 -6 , the Raman spectrometer needs to effectively filter the Rayleigh light and reduce the stray light background to obtain the Raman spectrum detection, so the filter device is a key part of the Raman spectrometer. According to the filtering method, the Raman spectrometers currently on the market are mainly divided into two categories: one is a single-stage spectrometer using optical filters; the other is a multi-cascade spectrometer using slit or pinhole spatial filtering. [0003] For the spectrometers of the former type using optical filters, the filters h...

AI Technical Summary

Problems solved by technology

The disadvantage of this type of spectrometer is that the corresponding filter module needs to be replaced when the excitation wavelength is changed, so it cannot be applied to the situation where the excitation wavelength is continuously adjustable.

[0004] For the latter type of multi-cascade spectrometer, it is currently applicable to a spectrometer system with continuously adjustable excitation wavelengths. However, multi-stage spectrometers have problems such as large optical system, high cost, complex optical path and significant loss of signal light, which leads to low detection sensitivity. In addition, when applied to a micro-Raman system with a 180-degree Raman signal acquisition method, the introduction of laser light and the extraction of Raman signal light need to be achieved using a semi-transparent and semi-reflective beam splitter, resulting in laser and Raman The signal light intensity is lost by half, therefore, the detection sensitivity is further seriously attenuated

[0005] Although as early as many years ago, Semrock Corporation of the United States had developed a filter with a continuously tunable cut-off wavelength, and domestic scientific research groups applied this filter to their wavelength tunable system (Liu, X.-L .; Tan, P.-H., Rev.Sci.Instrum.2017, 88(8), 083114.), however, the design of the system cannot apply the filter to the laser light path to achieve low-loss laser The introduction of the Raman signal light and the extraction of the Raman signal light, an additional semi-transparent and semi-reflective beam splitter is used to replace the dichroic mirror, which will inevitably cause the signal light intensity to attenuate to a quarter

The reason why this tunable filter cannot be used for the introduction of laser light and the extraction of Raman signal light is that when the filter changes the cut-off wavelength, the incident angle of the filter needs to be rotated, resulting in the laser beam on the filter The reflection direction also changes accordingly, and the Raman microscope requires the direction and position of the laser beam to be constant along the optical axis. Therefore, the traditional filter-type Raman microscope cannot use a tunable filter that needs to be rotated to obtain Suitable for the function of continuously adjustable excitation wavelength

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