GB/T 26829-2011 "Indoor Test Methods for Ranging Parameters of Pulsed Laser rangefinders" is a standard designed to specify indoor test methods for detecting ranging parameters of pulsed Laser rangefinders by means of fiber optic simulation. The standard applies to the evaluation and acceptance of ranging performance of pulsed Laser rangefinders, where ranging parameters include parameters such as maximum range, minimum range, and ranging accuracy. The standard also includes terms and definitions of range finders, such as pulse Laser rangefinder, maximum range, minimum range, and ranging accuracy, to ensure uniform terminology and understanding. The optical fiber extinction ratio test is a part of this standard, which aims to test the extinction ratio parameters of the pulsed Laser rangefinder by simulating the standard distance target through the optical fiber to verify that it can meet the requirements of the maximum range under specified conditions.