Wavelength-tunable monochromatic vacuum ultraviolet light source output device and method

The invention discloses a wavelength-tunable monochromatic vacuum ultraviolet light source output device and method. According to the invention, two beams of fundamental frequency light generated by alaser system are obliquely incident to the edge of a focusing lens in a frequency mixing system at a small angle; vacuum ultraviolet light generated by four-wave mixing and residual fundamental frequency light are emitted from the focusing lens at different angles due to different refractive indexes in the same medium, so that the vacuum ultraviolet light is separated from fundamental frequency light; the monochromaticity of the vacuum ultraviolet light source is guaranteed, and meanwhile, the energy loss of the vacuum ultraviolet light source is reduced to the minimum due to the fact that noextra optical element is needed to be added; when the wavelength of the vacuum ultraviolet light source needs to be changed, the wavelength of the fundamental frequency light is changed, and only thedistance of the lens devia