Question: A scanning laser device, similar to the one shown in Figure 23.13, is to be used to measure the diameter of shafts that are ground in a center less grinding operation. The part has a diameter of 0.475 in with a tolerance of ±0.002 in. The four-sided minor of the scanning laser beam device rotates at 250 rev/min. The collimating lens focuses 30° of the sweep of the mirror into a swath that is 1.000-in wide. It is assumed that the light beam moves at a constant speed across this swath. The photo detector and timing circuitry is capable of resolving time units as fine as 100 nanoseconds (100 × 10-9sec).This resolution should be equivalent to no more than 10% of the tolerance band (0.004 in).
(a) Determine the interruption time of the scanning laser beam for a part whose diameter is equal to the nominal size.
(b) How much of a difference in interruption time is associated with the tolerance of 10.002 in?
(c) Is the resolution of the photo detector and timing circuitry sufficient to achieve the 10% rule on the tolerance band?
