Double or multiple prisms, i.e. having two or more prisms in cooperation

Full Title

Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation , reproducing using an optical beam at lower power ; Record carriers therefor (G11B11/00, G11B13/00 take precedence) > Heads, e.g. forming of the optical beam spot or modulation of the optical beam (disposition or mounting of head elements within housing or with provision for moving of light source, optical beam or detector, irrelevant to the transducing method G11B7/08 ) > Means for guiding the beam from the source to the record carrier or from the record carrier to the detector > Double or multiple prisms, i.e. having two or more prisms in cooperation