Cal. Code Regs. tit. 13 § 713
Driving, fog, and passing lamps shall be centered on a goniometer, operated at design voltage, and aimed in a dark room on a perpendicular screen 7.5 m (25 ft) from the lamp. The goniometer shall be adjusted until the observer considers the visual aim on the screen to be correct in accordance with Sections 674, 675, or 680 of this title. Each of three experienced observers shall aim the lamp at least three times and each observer's goniometer settings shall be individually averaged. The deviation of each observer's averaged reading from that of any other observer shall not be more than 0.2 deg in the vertical direction and 0.4 deg in the horizontal direction.
Cal. Code Regs. Tit. 13, § 713
Note: Authority cited: Section 26103, Vehicle Code. Reference: Sections 24012 and 26103, Vehicle Code.