Lamp

A lamp characterized by comprising:

• a light source includes laser diode and a wavelength conversion plate, laser light emitted by the laser diode is focused on the wavelength conversion plate and excites the wavelength conversion plate to form a excitation spot and emit converted light, and the excitation spot on the wavelength conversion plate is called excitation area, and area outside the excitation area on the wavelength conversion coating is called non-excitation area;
• a diaphragm is located after and close to the wavelength conversion plate along the optical path, and the diaphragm includes light transmitting region and light blocking region which are closely adjacent to each other, and the light transmitting region is aligned to the excitation area of the wavelength conversion plate, and the distance from at least one point on the edge of the light transmitting region to the center of the excitation area is less than the characteristic distance, where the characteristic distance L is equal to L=2dtgθ, where θ=arcsin(1/n), d and n are the thickness and refractive index of the wavelength conversion plate, respectively;
• alight collimation element used for receiving and collimating light emitted from the diaphragm.