Double-beam spectrometer

The invention discloses a double-beam spectrometer, which comprises a light source for emitting reference light and detection light and a spectrometer main unit. The double-beam spectrometer is also provided with a first optical fiber, a second optical fiber and a third optical fiber, wherein the first optical fiber is used for transmitting the reference light from the light source to the spectrometer main unit; the second optical fiber is used for transmitting the detection light from the light source to a sample; and the third optical fiber is used for transmitting the detection light with sample information from the sample to the spectrometer main unit. The spectrometer main unit comprises a slit piece, a collimating lens, a plane grating, an imaging lens, a cylindrical lens and an area array detector, which are sequentially arranged along a light path. The emergent light of the first and second optical fibers enters the slit piece. The reference light and the detection light are simultaneously displayed and received, and the influence of light source fluctuation, stray light and electrical noise is effectively eliminated.