The invention provides a data output control apparatus which allows detailed information on a network to be readily obtained, which is advantageous with respect to cost, and which is suitable for specifically notifying the user of the service charge. By using a surrounding surface having a different reflectivity characteristic relative to the pin minor, the reflected wave front contains predominately single-pass aberration content because the amount of double-pass content is significantly reduced. The apparatus can be easily rolled up or folded like a rag for storage or transport.