(1986) Introduction to Classical and Modern Optics Optica Acta: International Journal of Optics: Vol 33, No 7, pp 822-823

Introduction to Classical and Modern Optics

Implementation and use of an automated projection Moiré experimental set-up

Three optical, noncontact, automated experimental techniques for determining the topography of object surfaces were assessed. The main objective was to test the limitations of three experimental techniques: projection moire, stereo imaging, and phase-measuring profilometry. Phase-measuring profilometry is the most promising of the three techniques for mapping rock fracture surfaces automatically, accurately, quickly, and with high resolution. The experimental set-ups used to assess these different techniques are similar, and they require essentially the same equipment. It is relatively easy and inexpensive to go from one experimental set-up to another. Also, the experience gained in implementing one experimental technique is often applicable in another, although the basic principles of each experimental technique are sometimes very dissimilar. The first technique, projection moire, is an optical experimental technique that is useful for displaying and measuring the three-dimensional form of large objects. Manual analysis of

/pdf/optical-noncontact-automated-experimental-techniqes-for-3bstjkbxx6.pdf

Optical, noncontact, automated experimental techniqes for three-dimensional reconstruction of object surfaces using projection moire, stereo imaging, and phase-measuring profilometry

Pacific University, College of Optometry, Forest Grove, Oregon 97116 Received 8 December 1986. 0003-6935/87/071166-02$02.00/0. © 1987 Optical Society of America. We have found that moire fringes can be easily evaluated by using the fringe spacing without knowing the dimensions of the actual experiment involved. That is similar to interferometry where the depth of a defect or other surface irregu­ larities can be found directly from the fringe distortions. Consequently, determining the magnification, or the rota­ tion of one grid relative to the other, and calibration of the apparatus in general, are not much of a problem anymore. Following Rayleigh's first observation, the evaluation of moire fringes is easy when one of two identical linear grids is rotated through an angle θ. If the separation of the lines in the original grids is d, the spacing M of the resulting moire fringes is

Moire topograms: a simple method for their evaluation.

A simple optical system was devised, using the projection method, to produce, observe, and photograph moire patterns on a sphere approximating the size of the cornea. Measurements of moire fringe deflections were taken off the photograph and used to calculate the depth of the defect that caused the deflection. Calculation of defect depth was within .025 mm (15 percent) of depth as physically measured with a micrometer.

Ray J. Weekly

Papers

Moire topograms: a simple method for their evaluation.

Use of moire patterns to measure defect depth on a convex spherical surface