Browse Prior Art Database

Compact Beam Bender

IP.com Disclosure Number: IPCOM000034357D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 214K

Publishing Venue

IBM

Related People

Groot, J: AUTHOR [+2]

Abstract

An optical element, which is used to deflect an anisotropic light beam 1 by 90o, while shaping the output beam 2 to have a substantially circular cross-section ("circularization"), comprises a prism 3 onto which the input beam is directed at grazing incidence (Fig. 1). The rear side of the prism is metallized for total reflection. On the front side, a multilayer coating is provided minimizing reflective losses of the input and output beams. In an embodiment, the wedge angle of the prism is about 10o and the incidence and output angles 75o and 15o, respectively. The beam is widened by a factor 3. A suitable multilayer coating for polarized beams may consist of eight layers (Fig. 2) yielding a transmission of 78% for the p-component and 22% for the s-component at an angle of incidence of 75o .

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Compact Beam Bender

An optical element, which is used to deflect an anisotropic light beam 1 by 90o, while shaping the output beam 2 to have a substantially circular cross-section ("circularization"), comprises a prism 3 onto which the input beam is directed at grazing incidence (Fig. 1). The rear side of the prism is metallized for total reflection. On the front side, a multilayer coating is provided minimizing reflective losses of the input and output beams. In an embodiment, the wedge angle of the prism is about 10o and the incidence and output angles 75o and 15o, respectively. The beam is widened by a factor 3. A suitable multilayer coating for polarized beams may consist of eight layers (Fig. 2) yielding a transmission of 78% for the p-component and 22% for the s-component at an angle of incidence of 75o . Alternatively, the incident and the exiting beam may be geometrically separated. For inexpensive batch fabrication of the prism, two plates of glass are each polished on one side, glued together, using a cement matching the refractive index, and then cut into individual prisms. Achromaticity can be achieved by using different optical materials for the two plates. Such beam benders can be used to save space and components in optical disk systems for directing the asymmetric output beam of a laser diode onto the optical disks surface.

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By cascading two prisms, the circularization process can be performed in two steps at greater angles of incid...