A stylus profilometer is an instrument used to measure the surface profile of an object. It works by moving a sharp-tipped stylus across the surface of the object and measuring the height of the surface at various points. The data is then used to create a detailed profile of the object's surface. This can be used to identify faults, defects, and other irregularities in the surface of the object. The stylus profilometer is an invaluable tool in industries such as automotive, aerospace, and medical device manufacturing.