Two chambers, a and b, are separated by p a rtitio n d which has
slit c. L ig ht source 2 is arranged in chamber a and, through
slit c, it illum in a te s phototube 3 in chamber b. Lenses 7 are
provided between lig h t source 2 and phototube 3 to focus and
direct the lig h t beam. The lower tip of measuring spindle 1
contacts workpiece e being inspected. The am ount th a t shutter^/,
mounted at the top end of spindle 1, covers slit с depends ;upon
the size of workpiece e. The intensity of illu m in a tio n of phototube
3 an d, consequently, the photoelectric current, depend
upon the position of shutter f, i.e. on the size of workpiece e.
$4373$SmE,M$