US 7,321,542 B2
Beam shaping prism and optical pickup employing the same
Jong-chul Choi, Suwon-si (Korea, Republic of); and Tae-kyung Kim, Seoul (Korea, Republic of)
Assigned to Samsung Electronics Co., Ltd., Suwon-si (Korea, Republic of)
Filed on Jan. 13, 2005, as Appl. No. 11/33,625.
Claims priority of application No. 10-2004-0002257 (KR), filed on Jan. 13, 2004.
Prior Publication US 2005/0152051 A1, Jul. 14, 2005
Int. Cl. G11B 7/00 (2006.01); G02B 5/04 (2006.01)
U.S. Cl. 369—112.28  [359/837] 41 Claims
OG exemplary drawing
 
10. An optical pickup including a beam shaping prism and which shapes a first beam emitted by a light source, focuses the shaped first beam onto an optical information storage medium by an objective lens, and receives a reflected beam from the optical information storage medium by a photodetector, wherein the beam shaping prism, comprises:
a first prism having an incident surface and a second prism having a surface inclined to an interface with the first prism, and
wherein when an angle that the incident surface makes with the first beam having an incident angle of θ1 is α1 and an angle that the inclined surface makes with an exit beam that passes from the first prism into the second prism and is reflected from the inclined surface is α2, the beam shaping prism satisfies a first equation and allows the exit beam to emerge perpendicularly to the first beam:

OG Complex Work Unit Drawing
where n1 and n2 are refractive indices of the first and second prisms, respectively, θ2 is a refraction angle of a second beam that is the first beam that is refracted through the incident surface of the first prism, θ3 is an incident angle of a third beam that is the second beam that passes from the first prism into the second prism, θ4 is a refraction angle of a fourth beam that is the third beam that is refracted through the first prism into the second prism, and θ5 is an angle that the fourth beam traveling through the second prism is incident on the inclined surface of the second prism.