Optical element, method of manufacturing the optical element and optical head using the optical element

摘要

An optical element is composed of a first substrate (11) and a second substrate (12) that are joined to each other. The first substrate (11) is composed of a plurality of transparent base materials joined to each other through a first joint surface (11a) on which an optical film is formed. The second substrate (12) is composed of a plurality of transparent base materials joined to each other through at least two second joint surfaces (12a) to (12c) parallel to each other. On each of the second joint surfaces, an optical film is formed. One part of light incident on the first substrate (11) is reflected from the first joint surface (11a) to be incident on the second substrate(12), and at least one part thereof is reflected from at least one of the second joint surfaces. A virtual plane including an incident light axis and a reflected light axis on the first joint surface (11a) and a virtual plane including incident light axes and reflected light axes on the respective second joint surfaces (12a) to(12c) form an angle of substantially 45 degrees. This allows an optical element to be manufactured at a reduced cost, in which no diffraction grating is provided on an optical path from a light source to an optical disk, so that a high light utilization efficiency can be attained, and the degradation in signal quality can be prevented.