Lépaisseur

Lépaisseur, or épaisseur in French, denotes the dimension of an object measured perpendicular to its faces; it is the distance between two parallel surfaces. It is a distinct geometric property from length and width and is especially important for sheets, films, coatings, and layers.

Thickness is measured with a range of instruments tuned to the size and material of the object. For small parts, calipers or micrometers are common; coating thickness gauges are used for films; profilometers or optical methods measure surface profiles; ultrasonic or X-ray techniques are used for layered or opaque samples. Units include meters, millimeters, micrometers, and nanometers, with tolerances specified where precision matters.

Applications include manufacturing and quality control of metal sheets, plastics, glass, and coatings; in electronics for film thickness of semiconductor layers and dielectric coatings; in optics for anti-reflective or protective coatings; and in geology for the vertical extent of layers such as ice sheets or crust. Thickness affects strength, insulation, optical transmission, and overall performance of materials and structures.

Uniform thickness across a part is often required; nonuniformity is described as thickness variation. Standards and metrology methods exist to ensure accuracy and repeatability in industry, and thickness data inform design choices and material performance.