Main feature: 1, with the determination of spectral transmittance function. 2, with the mouth and the photon detector integral ball. 3, with an optical device capable of generating a double beam. 4, two parallel beam of light and its beam axis of the incident angle of not more than 5 °. 5 has a function of scanning at a desired wavelength interval in the wavelength range of 380 nm to 780 nm. 6, with the sample in the tension-free state to keep the sample folder.