| 摘要 |
934,920. Kerr effect records. NATIONAL CASH REGISTER CO. April 25, 1962 [May 19, 1961], No. 15678/62. Class 40 (2). A Kerr record for use with apparatus such as described in Specification 883,936, comprises a base 12, successively coated in vacuo with a reflective silver layer 13 and a magnetic layer 14 of Fe-Co, Fe, Co or Ni whose thickness is of the order of one quarter of the wavelength of the incident radiation B1 and which is therefore optically transparent. The thickness of the layer is such that the rotated rays B20 reflected from the upper surface and B21 reflected from the layer 13 and twice refracted in the layer 14 interfere with a consequent improvement of signalto-noise ratio. The behaviour of the various materials for the layer 14 with thickness and in the presence or absence of the layer 13 are displayed graphically (Figs. 3-6, not shown). |
