The included angle of the tester level sight line and observing sight line is zero.The straight rail and driven test car can make the tester see the pattern rotating along anticlockwise or clockwise.

• 驱动测试车，使测试者在测试板前面不间断地进行往返运动，测试者会看到，测试板上的图案在圆周上沿圆心做逆时针或顺时针转动。