Photo interrupter (ITR for short), which is called light interrupter in Chinese, belongs to a kind of photoelectric element. It is composed of light emitting element and light receiving element; During operation, the light emitting end turns electricity into light, and then the light receiving end turns electricity into electrical signal. Through the conversion of light and electricity, we can sense the existence and proximity of external objects. This product has fast response, high sensitivity and small package size, and is suitable for SMD package.