through the openings 54f and 54e can be measured as the meridian direction passing through the openings 54a and 54b the light beams passed through the openings 54a and 54b need not be rotated and therefore the small prisms 55a and 55b can be eliminated the deflecting prism 55 34 serves to separate the six images passed through the six openings from one another at a suitable interval and by suitably choosing the angle of inclination of the end surface of the rotating prism 55 39 the deflecting prism 55 34 and the rotating prism 55 39 can be made integral with each other fig2 shows the six images a f on the area sensor array 44 the images a f have been formed by the light beams passed through the openings 54a 54f the values of refraction in three meridian directions can be found from the intervals on a scanning line s between these three sets of images a and b c and d and e and f generally the value of refraction of an eye is considered to vary in a sine wave like fashion relative to the meridian direction and therefore if the values of refraction in three meridian.