The instrument uses the integral sphere to measure the absolute spectral diffuse reflectance, and the optical principle is that the blue light emitted from the semiconductor light source directly enters the integrating sphere, blue light after the integration of the inner wall diffuse reflection, irradiation in the test mouth of the sample, from the sample surface reflected by the spectrum of condenser, light column, filter group from the silicon light cells received to convert to electrical signals; Two-way signal amplification, and by single-chip processing, the realization of automatic school 0, work Whiteboard calibration, sample testing system functions, users can be very easy to use the instrument for various samples of whiteness test.