Optical head and optical head device
a head and optical technology, applied in the field of optical head and optical head device, can solve the problems of indispensably increasing size and weight, difficult to adopt air floating method, and strong limitations in design, and achieve the effect of simple optical system
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first embodiment
; See FIGS. 1, 2 and 3
[0049] In FIGS. 1 and 2, the number 1 denotes a recording medium, and the number 10 denotes an optical head device. The recording medium 1 has a recording layer 3 on a substrate 2 and can be driven to rotate on a rotary driving shaft 4. A protective layer may be formed on the recording layer 3.
[0050] The optical head device 10 has a prism 12 serving as an optical head at the end of an arm 11. On the arm 11, a light source 15, a collimator lens 16 (see FIG. 2), a polarizing beam splitter 17, a λ / 4 wavelength plate 18, an optical detector 19 are provided. The prism 12 has an incident surface 12a, an internal reflective surface 12b and an emergent surface 12c. The incident surface 12a and the emergent surface 12c are plane, and the internal reflective surface 12b is a paraboloid of revolution, of which top is an end P of the surface 12b (see FIG. 3). This internal reflective surface 12b is made by forming a reflective material 13 such as Au, Ag, Cu, Cr, Ni, Al or...
second embodiment
; See FIG. 9
[0063] In the second embodiment, for recording, reading and erasing, light of a wavelength λ1, light of a wavelength of λ2 and light of a wavelength of λ3 are used, respectively. The second embodiment is of the same structure as the first embodiment. The light source 15 has light emitting sources which emit light of a wavelength λ1, light of a wavelength of λ2 and light of a wavelength of λ3, respectively and switches these light emitting sources for recording, reading and erasing to emit the light of the respective wavelengths toward the prism 12.
[0064] In this case, the recording layer 3 is preferably a photochromic medium. As a specific example, 1,2-bis (2,4,5-trimethyl-3-thienyl)-cis-1,2-dicyanoethene (trade name, made by Tokyo Chemical Industry Co., Ltd.) can be named. For such a recording layer 3, light of 355 nm is used for recording; light of 632 nm is used for reading; and light of 780 nm is used for erasing.
[0065] Recording, reading and erasing in the second ...
third embodiment
; See FIGS. 10 and 11
[0066] The third embodiment is a compatible optical head device which has a prism 22 so as to carry out recording, reading and erasing not only by a near field light but also by a propagated light beam. Accordingly, this device also can be used to record, read and erase information to and from conventional optical disk media such as CDs, DVDs, etc. by use of a propagated light beam.
[0067] The head using a near field light is basically of the same structure as that of the first embodiment, and in FIG. 10, the same members are denoted by the same reference symbols as in FIG. 1. Referring to FIG. 11, the prism 22 has an incident surface 22a and an internal reflective surface 22b on which a reflective film 23 is formed. A near field light N effuses through an emergent surface 22c at a converging point O. The internal reflective surface 22b is a paraboloid of revolution of which top is its end P.
[0068] Recording, reading and erasing by use of the prism 22 and the n...
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Abstract
Description
Claims
Application Information
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