Optical: systems and elements – Single channel simultaneously to or from plural channels – By partial reflection at beam splitting or combining surface
Reexamination Certificate
1999-02-17
2001-04-17
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By partial reflection at beam splitting or combining surface
C359S640000, C359S631000, C345S007000, C345S008000
Reexamination Certificate
active
06219188
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an observation system having a half mirror suited to a photographing apparatus such as a head mounted display or video camera which is designed to observe both video information, e.g., a liquid crystal display image, displayed on a display means and scenery image information within the same visual field, and a method of manufacturing the half mirror.
2. Description of the Related Art
A half mirror for splitting a light beam into a plurality of beams has been used in a conventional observation system for simultaneously observing pieces of image information, displayed in different directions, within the same visual field. For example, the optical system of an observation system mounted on a photographing apparatus such as a head mounted display or a video camera, which is designed to observe both image information, e.g., a liquid crystal display image, displayed on a display means and scenery image information within the same visual field, includes a half mirror for reflecting a liquid crystal display image toward the eyes of the observer and transmitting an external scenery image therethrough. As such a half mirror, for example, a dielectric multilayer film obtained by alternately stacking high-refractive-index films and low-refractive-index films, each consisting of a dielectric material, or a metal half mirror formed by sandwiching a metal film between dielectric films is often used.
According to conventional techniques of manufacturing half mirrors made of dielectric multilayer films or metal films, a large number of films are required for a dielectric multilayer film to obtain a relatively high reflectance in the visible region. In general, as the number of films to be formed increases, it becomes more difficult to manufacture a half mirror. In addition, the manufacturing cost increases, and the deflection characteristics of the dielectric multilayer film and the flatness of the spectral distribution deteriorate.
When a metal film is to be used, the deflection characteristics and the flatness of the spectral distribution are relatively good, but the film undesirably absorbs light. As a result, the optical characteristics of light amount splitting between transmitted light and reflected light deteriorate.
With the use of the conventional half mirror surface manufacturing techniques, it is difficult to obtain a half mirror that can satisfy both the requirements for optical characteristics and the manufacturing method.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an observation system having a half mirror which exhibits a flat spectral distribution in a wide visible region, has excellent optical characteristics with a small light absorption, and allows an easy manufacturing process, and a method of manufacturing the half mirror.
An observation system having a half mirror according to the present invention is (1—1) an observation system for observing video information in the visible region which is displayed on a display means by guiding the information to an eyeball of an observer using an observation optical system having a half mirror, characterized in that the half mirror is made up of a plurality of metal films and a plurality of dielectric films.
(1—1—1) The plurality of metal films are made of chromium and silver.
(1-1-2) The thickness of the chromium film falls within the range of 0.1 to 10 nm.
(1-2-3) A material for the dielectric film is one member selected from the group consisting of SiO, SiO
2
, MgF
2
, Al
2
O
3
, ZrO
2
, TiO
2
, Ta
2
O
5
, ZnS, and mixtures thereof.
(1-2-4) The observation optical system includes an optical element made of a prism member and a see-through prism member. The optical element has an incident surface on which a light beam from the display means is incident, a front surface which partly uses a total reflection surface for the light beam from the incident surface, and a reflecting surface for reflecting the light beam toward the front surface side. The prism member has an incident surface on which a light beam bearing scenery image information is incident, and an exit surface having substantially the same shape as that of the exit surface of the optical element. The reflecting surface of the optical element opposes the exit surface of the prism member. The half mirror has the reflecting surface of the half mirror directed to the exit surface of the prism member.
(1-1-5) After the light beam bearing the scenery image information is incident on the incident surface of the prism member and output from the exit surface of the prism member, the light beam reaches the observer side through the reflecting surface and front surface of the optical element.
(1-1-6) The optical element and the prism member are joined to each other.
A method of manufacturing a half mirror according to the present invention is characterized as follows:
(2-1) In manufacturing a half mirror used to observe video information in the visible region which is displayed on a display means by guiding the video information to an eyeball of an observer, the method includes the steps of forming a plurality of metal films on a surface of a substrate, and forming a dielectric film. In the respective steps, the substrate is not heated.
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patent: 1-134401 (1989-05-01), None
patent: 5-127004 (1993-05-01), None
Tsukamoto Mayumi
Tsukamoto Seitoku
Canon Kabushiki Kaisha
Epps Georgia
Robin Blecker & Daley
Thompson Tim
Tsukamoto Mayumi
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