JP2544456B

PURPOSE:To enhance detection sensitivity and an S/N ratio by superposing non-magnetic austenite type stainless steel on ferromagnetic steel and heating both of them at a desired interval on the side of the austenite type stainless steel using a high energy density heat source. CONSTITUTION:A base plate 1 is constituted by superposing plate-shaped non- magnetic austenite type stainless steel 2 on plate-shaped ferromagnetic steel 1. Laser beam or electron beam 20 being a high energy density heat source is applied to the heated parts 3 of the base plate 1 so as to form a desired interval between the heated parts 3 to heat the same and at least a part of the non-magnetic steel and the ferromagnetic steel 1 is melted at the heated parts 3 to be solidified. The non-magnetic steel 2 is melted by the irradiation with laser beam to be mixed with the ferromagnetic steel 1 and subsequently solidified to form magnetic grids to the base plate 11 at a predetermined interval. By irradiating the base plate 1 with beam to arbitrarily select the interval between the magnetic grids formed on the substrate 1 and using a magnet 4 and an element for detecting the quantity of magnetic flux 30, for example, a Hall element, the relation between displacement quantity and residual magnetization quantity is obtained and displacement can be detected.