Stock material or miscellaneous articles – Circular sheet or circular blank
Patent
1995-06-05
1996-10-29
Ryan, Patrick
Stock material or miscellaneous articles
Circular sheet or circular blank
428 642, 428 644, 428 645, 428 646, 428913, 4302701, 43027011, 43027012, 43027013, 4304951, 430945, 3692752, 369283, 369288, B32B 300
Patent
active
055695175
ABSTRACT:
An optical information medium has on a substrate (2) with information-carrying pits (21), a light transmittance control layer (3) including a lower dielectric layer (31), a mask layer (32) and an upper dielectric layer (33). The mask layer has an original state before irradiation of reading light. Upon irradiation of a reading light beam to define a beam spot, the mask layer undergoes a crystal-to-crystal transition in a region (H) of the beam spot depending on the intensity distribution of the beam spot. Multiple reflection condition changes in the transition portion so that the beam spot contributing to read-out is limited to the transition or transition-free region (H or L). The transition temperature is in the range of 200.degree. to 450.degree. C. The mask layer returns to the original state after passage of the beam spot. The invention is also applicable to an optical recording medium having a recording layer above or below the transmittance control layer.
REFERENCES:
patent: 5153873 (1992-10-01), Spruit et al.
patent: 5348783 (1994-09-01), Ohno
patent: 5389417 (1995-02-01), Tominaga
patent: 5418030 (1995-05-01), Tominaga
Premastered Optical Disk by Superresolution; Yasuda et al. pp. 65-66; Joint International Symposium on Optical Memory and Optical Data Storage; Jul. 5-9, 1993.
Optical Storage Read-Out of Nonlinear Disks; Bouwhuis et al.; pp. 3766-3768; Applied Optics; vol. 29, No. 26; 10 Sep. 1990.
New Opto-Magnetic Disk, Irister; Miyaoka; pp. 393-398; Solid Phisics; vol. 26; No. 6 (1991).
Haratani Susumu
Inaba Ryo
Kuwahara Tsuneo
Tominaga Junji
Evans Elizabeth
Ryan Patrick
TDK Corporation
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