Active infrared detector

The utility model provides an active infrared detector. The active infrared detector comprises an infrared transmitting part and an infrared receiving part. The infrared receiver part comprises a first lens and an infrared light source which is located at the focus of the first lens and used for transmitting an infrared light ray. The infrared receiving part comprises a second lens and a receiver which is located at the focus of the second lens and used for receiving the infrared light ray. The infrared light ray transmitted by the light source passes through the first lens and the second lens to arrive at the infrared receiver. The detector is characterized in that at least one of the first lens and the second lens is a two-side aspherical lens; and each side of the two-side aspherical lens is convex. According to the utility model, the design that two sides of each lens are aspherical improves the depth of parallelism of the light transmitted by the receiver part, thereby enabling the receiving end to obtai