1. Sources and detectors: general information

Figure 1 - Variation in the diameter (defined as the distance from the axis for which the illuminance is 1/e2 times the illuminance on the axis) of a focused laser beam as a function of distance

Figure 2 - Variation of illuminance in the cross-section of a TEM00 laser beam

Figure 3 - Examples illustrating the diverse behaviour of illuminated surfaces

Figure 4 - Diagram of a photodiode

Figure 5 - Diagram of a four-quadrant cell

Figure 6 - PSD cell schematics

Figure 8 - Diagram of a triangulation displacement sensor

Figure 9 - Diagram of a linear transducer

Figure 10 - Diagram of sensors with multiple scattered light detection axes

Figure 11 - Diagram of a two-dimensional measurement system, with the measurement line in the triangulation plane.

Figure 12 - Diagram of a two-dimensional measurement system, with the measurement line in the plane perpendicular to the triangulation plane.

Figure 13 - Two-dimensional sensor using two cameras to measure part profile (source: Kréon)

Figure 14 - Diagram of a three-dimensional triangulation measurement system using two acousto-optic deflectors to designate the points to be measured (source: CETIM).

Figure 15 - White-light screen projection (source: GF Messtechnik GmbH)

Figure 16 - Pointed measurements on part edge

Figure 17 - Measuring the dimensions of elements in the field of the measured image (camera and vision system)

Figure 18 - Schematic diagram of a reflective displacement transducer

Figure 19 - Variation of measured intensity with distance for an uncompensated sensor

Figure 20 - Diagram of a compensated reflection displacement transducer

Figure 21 - Variation in intensity measured by each receiving fiber array and calculated output

Figure 22 - Schematic diagram of unidirectional reflection triangulation sensor

Figure 23 - Comparison of different light distribution methods for ombroscopy

Figure 24 - Direct measurement of a part by ombroscopy with a CCD detector

Figure 25 - Umbroscopy: the influence of source size on the abruptness of the black-to-white transition

Figure 26 - Influence of edge diffraction on illuminance in the vicinity of the geometric shadow

Figure 27 - Measurement of part edge position and distance between two cylinders

Figure 28 - Ombroscopy: using diffuse lighting

Figure 29 - Ombroscopy: laser beam scanning device

Figure 30 - Umbroscopy using laser beam scanning: variation in repeatability as a function of the number of measurements averaged

Figure 31 - Examples of umbroscopic measurements

Figure 32 - Examples of measurements on transparent or semi-transparent products