An optical disc apparatus according to the present invention is usable for an optical disc including a bar code area and a control data area adjacent to the bar code area in a radial direction of the optical disc. The antenna elements include two segments that meet at corners that are located at the vertices. A correlation value calculation circuit calculates a correlation value for gray image and a correlation value for color image. Then, a mark is inserted after all pulse signals are generated and had been delayed for a predetermined delay time. The present invention also includes unitary sample preparation and detection devices to be used in accordance with the methods. Functions of the riflescope include observing, aiming, and laser ranging and transmission using the same objective lens.