An optical testing apparatus is used in testing an optical measuring instrument. The optical measuring instrument provides an incident light pulse from a light source to an incident object and receives a reflected light pulse as a result of reflection of the incident light pulse at the incident object. The optical testing apparatus includes two or more testing light sources, two or more optical penetration members, and a wave multiplexing section. The two or more testing light sources each output a testing light pulse. The two or more optical penetration members each have an optical penetration region and receive the testing light pulse from each of the two or more testing light sources for penetration through the optical penetration region. The wave multiplexing section multiplexes the testing light pulses penetrating through the two or more optical penetration members for provision to the optical measuring instrument.