Optical scanning device

Abstract

An optical scanning device incorporating a compound objective lens 10 and a radiation detector 31 is described for reading an optical record carrier 1 in which the optical record carrier 1 is provided with a transparent layer 2 . The thickness of the transparent layer 2 and the effective radius of the detector 31 are adapted such that the signal-to-noise ratio of the device is significantly improved and/or local heating of an air gap below an air slider is reduced. The optical record carrier is provided with a lubricant to facilitate the use of a slider optical head 40.

1 - 17 . (canceled)  
     
     
         18 . An optical scanning device adapted to be used for scanning an optical record carrier when located in a scanning position in the device, the optical record carrier including an information layer for storing data and a transparent layer having a thickness of between 2 and 50 μm through which radiation passes to reach the information layer, the device including a radiation source for generating a radiation beam, an objective lens system located in the optical path between the radiation source and the scanning position of the optical record carrier, a slider for flying at a height of less than 20 μm above the optical record carrier and having a transparent portion for transmitting said radiation beam, and a radiation detector for detecting radiation reflected by the optical record carrier.  
     
     
         19 . An optical scanning device according to  claim 18 , wherein said thickness is approximately 20-30 μm.  
     
     
         20 . An optical scanning device according to  claim 18 , wherein said thickness is approximately 7-15 μm  
     
     
         21 . An optical scanning device according to  claim 18 , wherein said slider is adapted to operate with a flying height of approximately 1 to 2 μm, and said thickness is between 7 and 50 μm  
     
     
         22 - 25 . (canceled)