Apparatus for measuring internal stresses in thin layers

摘要

The measuring strip (11) is vertically clamped between fixed and movable holders (3, 6) so that the movable holder (6) measures the change in the length of the measuring strip. Both holders are made of materials with a small or extremely small coefficient of thermal expansion. Preferred Features: The fixed holder (3) consists of one or more quartz glass rods or tubes with a diameter from 3 to about 30 mm. Alternatively it consists of metals with a small or extremely small coefficient of thermal expansion. The nonmetal fixed holder has a metal screw connector (2), and is adjustably secured by the latter to a platform (1). The fixed holder is shaped as an 'L' or a 'U', for example. The movable holder is made of quartz glass or metals with a small or extremely small coefficient of thermal expansion. The variation in the length of the measuring strip (11) is determined using a clock gage, or a capacitative or inductive displacement sensor. The probe of the measuring system rests on a disk of quartz glass at the top end of the movable holder. The measuring system is connected to a computer for on-line processing of the measurement results. The measuring system alternatively can be used in a horizontal orientation.