The utility model relates to an optical instrument, which is an optical palette instrument which makes use of changeable or a deformable optical elements to change the light beam and spectrum distribution. Via the optical systems of a condensation system i, a slit, a collimation object lens, a dispersion element, a focusing imaging object lens, a color selecting diaphragm, a condensation system ii and a color mixer, the light source can adjust and change the geometric form (position, shape and size) of the color selecting diaphragm in order to get the required multi-color light, single color light and negative single color light distributed in difference light spectrums.