Triangulation refers to a geometric method of optical distance measurement by precise calculation of angles within triangles. It is therefore based on the mathematical subdiscipline of trigonometry and the associated trigonometric functions. Triangulation methods are used for non-contact distance and length measurements in close-range industrial applications. For this purpose, a light source is focused at a specific angle on a measurement object, whereupon an electronic image converter such as a camera registers the scattered light. The connection between the camera and the light source and the two beams from and to the object form a triangle, which is why this type of method is called triangulation. Thus, the triangular mathematics known since ancient times and its formulas for the calculation of unknown quantities is still the most important mathematical reference system for the trigonometrically working methods of modern metrology. The method is used in many metrological applications, among others in the light section or the fringe projection.