The invention relates to an optical device, particularly a portable high stability optical source suitable for the near infrared spectrometric analyzer. A control circuit receives the signal of the photoelectric detection to generate the control signals and the control circuit drives a light path through the driver module, outputs the near infrared light through the optical fiber interface. The cavity bottom of the light path system is an ellipse reflecting surface or a parabolic reflecting surface, the peak of which is arranged with a tungsten halogen lamp with the top having a light outlet, the external end of which is provided with an optical fiber interface, for projecting the generated light onto the required device. The design of the closed loop system advances the stability of the light source, increases the anti-interference ability, reduces the fluctuation of the supply voltage, the electromagnetic interference, the aging of the element. The sheathing materials adopt aluminum, which is favorable for the thermolysis; the simple light path has compact and firm design structure; the integral design makes the device convenient to carry along, which is used in the lab and the field experiment.