1. Field of the Invention
This invention relates to a camera having a holographic indicator and more particularly to a camera having a holographic indicator which forms a reconstructed image of a hologram on the same plane as that of an object's image formed by an image forming optical system.
Generally the term "hologram" is used to mean interference fringes which are formed by an object's wave front and a reference wave front and are recorded on a hologram recording medium. However, this term "hologram" is used herein for a broader concept to include also interference fringes produced by means other than the above stated means such as the interference fringes produced by a ultrasonic bulk wave, a computer calculated hologram and the like.
2. Description of the Prior Art
In the past, a holographic indicator similar to the present invention has been disclosed in the specification of U.S. Pat. No. 3,560,921. In this patent a hologram is disposed at a sight window provided in a helmet for a pilot to enable him to observe a far distant object simultaneously with a hologram image which is reconstructed at the far distant position.
However, unlike the device disclosed in the above stated U.S. Patent, this invention relates to a holographic indicator wherein a reconstructed hologram image is formed on the same plane as that of an object's image formed by an image forming optical system.