| 摘要 |
<p>A method for checking the repeat accuracy in an endless pattern employs an optical device to superimpose adjacent pattern repeats on one another. The endless pattern having a repeat length is placed on a light table comprising a frosted glass screen illuminated by a number of lamps. Further lamps provide overhead illumination. The pattern repeat lines are reflected by a pair of mirrors and the image is viewed by an observer after further reflection in the silvered surfaces of a prism. by slight movement of the eye, the observer can determine the accuracy of the pattern repeats, whose positions may be measured by means of scales mounted on the sides of the apparatus.</p> |
