Abstract: Electromagnetic noise absorbing material and filter, which are small, light, and effective even with respect to unwanted electromagnetic waves of a few hundred MHz or more, are provided. A small and flexible electromagnetic noise filter cable and tape-shaped electromagnetic noise filter, as well as a manufacturing method and manufacturing apparatus therefor, are also provided. The electromagnetic noise absorbing material has a thickness or particle diameter of the alloy magnetic substance which is within a range of from 1/10 to 10 times the skin depth thereof, and thereby, a large eddy current loss can be generated, so that it is possible to manufacture electromagnetic noise filters having various shapes, which are small, light, and which realize a large electromagnetic noise suppression effect as a result of eddy current loss, and these possess a large relative magnetic permeability even at levels of a few hundred MHz or more.

Abstract: In a magnetic field sensing method in accordance with the invention of the present application, a magnetic sensor comprising a conductor and at least one magnetic material provided on any of the surfaces of this conductor, is employed. This magnetic sensor is disposed in the vicinity of an external magnetic field which is to be sensed, and by means of supplying a high frequency current to this conductor, the impedance of the conductor changes in accordance with the external magnetic field, and based on this, the external magnetic field is sensed.

Abstract: In a magnetic field sensing method in accordance with the invention of the present application, a magnetic sensor comprising a conductor and at least one magnetic material provided on any of the surfaces of this conductor, is employed. This magnetic sensor is disposed in the vicinity of an external magnetic field which is to be sensed, and by means of supplying a high frequency current to this conductor, the impedance of the conductor changes in accordance with the external magnetic field, and based on this, the external magnetic field is sensed.

Abstract: In a magnetic field sensing method in accordance with the invention of the present application, a magnetic sensor comprising a conductor and at least one magnetic material provided on any of the surfaces of this conductor, is employed. This magnetic sensor is disposed in the vicinity of an external magnetic field which is to be sensed, and by means of supplying a high frequency current to this conductor, the impedance of the conductor changes in accordance with the external magnetic field, and based on this, the external magnetic field is sensed.

Abstract: A micro optical head, for optically reading and/or writing digital data on a recording medium in which digital data 1 and 0, corresponding to a high reflection factor and a low reflection factor, is composed of a self-coupled semiconductor laser located close to the recording medium. A bias current of the laser is determined so that it is smaller than a first threshold current, in which the medium has a low reflection factor, and is higher than a second threshold current, in which the medium has a high reflection factor. Output light of the laser is either strong stimulated emission light, corresponding to the high reflection factor, or weak spontaneous emission light, corresponding to the low reflection factor. The present head is carried on a flying slider with a spacing length less than several .mu.m which provides a small beam spot of about 1 .mu.m, and has an excellent signal to noise ratio.

Abstract: An improved method for manufacturing a floating type thin film magnetic head, which comprises the steps of depositing numerous thin film transducers in a matrix form on a lapped plain surface of core block stock; cutting the core block stock into a plural number of narrow parallelepiped core blocks each containing a row of deposited thin film transducers; placing a thin patterned mask on the lapped recording medium-facing plane surface of each slender core block; ion-etching the tape-facing plane of each narrow core block by irradiating accelerated ions of argon gas through the patterned mask to provide an air-bearing surfaces for the respective magnetic heads; and cutting up the respective processed narrow core blocks into individual magnetic heads.