The projector is a special optical instrument designed and developed for preparing to test the V-shaped or U-shaped notch processing quality of impact specimen. The processed specimen notch is amplified for 50 times and projected onto the observation screen; Then a comparison is carried out with the standard drawing board inscribed on the observation screen and it is can be rapidly determined whether the notch of the impact specimen is qualified. The comparison is directly visible and the operation is simple with high efficiency. The projector is indispensable special equipment for physicochemical laboratory.