4,929,402 5/1990 Hull 264/308
4,945,032 7/1990 Murphy 425/174
5,058,988 10/1991 Spence 356/121
5,059,021 10/1991 Spence et al 356/121
5,123,734 6/1992 Spence et al 356/121
OTHER PUBLICATIONS
Applied Optics, vol. 17, No. 17, Sep. 1978, pp.
2673-2674; P. J. Shalyer: "Laser Beam Distribution In
the Focal Region", (see FIG. 1, p. 1).
Abstract of JP 62-163933 (Nippon Kogaku K.K.) Jul.
20, 1987.
Primary Examiner—Richard A. Rosenberger
Assistant Examiner—Hoa Q. Pham
Attorney, Agent, or Firm—Lyon & Lyon
[57] ABSTRACT
An apparatus and a method for profiling the intensity of a beam and thus measuring the overall intensity and power of a beam are disclosed that have particular use in stereolithography. A beam sensor comprising a pinhole in a plate and a photodetector behind the pinhole measures the intensity of portions of a beam as the beam is moved over the beam sensor. Software associated with the sensors in a computer controls the scanning mechanism for the beam so that the beam is shifted to find the pinhole and move across it in order to develop the intensity profile. The invention can be used to detect drift in the scanning mechanism, determine the focus of the beam, and predict the depth and width of photopolymer cured by the beam.
40 Qaims, 13 Drawing Sheets
