Consisting of diffraction grating, monochromatic 150 W xenon light source, and optical detector, Model SPG-120-REV targets high-accuracy optical spectroscopy. Grating is directly attached to 5-phase stepping motor with high reduction ratio harmonic drive gearing that enables wavelength positioning speed of 500 nm/s. With total area of 100 x 187 mm, SPG-120-REV is suited for 2D spectral mapping of solar cell materials and optical devices as well as in-line inspection of food.