PREPARATION OF MAGNETIC SCALE

摘要

PURPOSE:To enhance detection sensitivity and an S/N ratio by heating non- magnetic austenite type stainless steel at a desired interval by a high energy density heat source while a magnetic field is applied to said steel. CONSTITUTION:A current is supplied from a DC power supply 22 to form magnetic flux 30 and this magnetic field is applied to a base body composed of non-magnetic austenite type stainless steel. Laser beam 20 being a high energy density heat source is applied to said base body 1 so as to form a desired interval between heated parts 3 to heat and melt the same while the molten parts are solidified to form magnetic grids of a predetermined interval. About several % of magnetic ferrite is precipited in the austenite texture of each molten/ solidified heated part 3. Since a magnetic field is applied during the irradiation with laser beam, the axis of the precipitated ferrite magnetic body is aligned in a definite direction to generate magnetic anisotropy. Therefore, the interval between the magnetic grids is arbitrarily selected and a Hall element detecting residual magnetization quantity is used to obtain the relation between displacement quantity and residual magnetization quantity. By this method, displacement can be detected.