Method for shape detection and apparatus therefor

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
1 to 3, the shape detection apparatus in an embodiment according to the present invention generally includes means (not shown) for projecting light beams onto an object C the shape of which is to be detected, and means for receiving reflected beams of the projected beams from the object C, both means being disposed as mutually separated by a predetermined distance.
The beam projecting means projects onto a spot of the object C a plurality of the beams of light mutually different in the intensity as the different pattern and substantially in the same direction but with a relative time lag in a height direction (along the ordinate Z).
In this case, the respective projected beams provide a projected beam spot of a diameter ranging x.
sub.
1 -x.
sub.
2 in the drawings, and the plurality of the beams are projected as overlapped on one another to an identical spot of the range of x.
sub.
1 -x.
sub.
2.
Assuming here that two beams A and B are projected, for example, one projected beam A has such an intensity pattern as shown by a curve A1 in FIG.
2(a) in which the projected light intensity is high on one side of x.
sub.
1 of the spot and decreases linearly towards the other side of x.
sub.
2, whereas the other projected beam B has such an intensity pattern as shown by a curve B1 in FIG.
2(a) in which the intensity is high on the other side x.
sub.
2 and decreases linearly towards the one side x.
sub.
1.
Further, the beam receiving means includes a position detector 11 on which an image provided by the reflected beams from the object C is formed through a light receiving lens 12.
In FIG.
1, only one of the reflected beams which is on the optical axis of the light receiving lens 12 is shown with a solid line, and this applies to all following drawings.
For this position detector 11, it is preferable to employ one which comprises a light receiving element of a smaller diameter than that of formed-image spot of the received beams and set in array along a line in which the formed-image spot displaces in accordance with a height displacement with respect to a reference plane Z in the height direction for the positional detection of the object C, so that the respective reflected and received beams can be detected by the common light receiving element