 Optical head |
| Accordingly, it is an object of the invention to provide an optical head in which a diameter of a ... |
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| Optical head and optical data recording and reproducing apparatus having the same |
| According to one aspect of the invention, the optical head for reproducing data from first and ... |
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| Objective lens for recording and reproducing for use in an optical information recording medium |
| An object of the invention is to make it possible that recording and reproducing by means of ... |
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| Optical pickup used with both DVD and CD |
| The present invention has been made to solve above-mentioned problems and it is an object of the ... |
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| Objective lens for optical pick-up head of optical disk drive |
| It is therefore the principle object of the present invention to provide an objective lens for ... |
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| Optical head |
| For solving the problem of the prior art, an optical head of the present invention comprises, light ... |
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Multifocal objective
| Details |
Inventors: Alfredsson, Hans; Moller, Bo; Ingelstam, Erik; Ohlsson, Per-Olof; Vogl, Georg;
Assignee: AB Svensk Filmindustri (Stockholm, SE); Svenska Ord AB (Stockholm, SE)
Primary Examiner: Corbin; John K.
Assistant Examiner: Sugarman; Scott J.
Attorney, Agent or Firm: Pollock Vande Sande & Priddy
The present invention relates to an image-forming objective which is capable of forming sharp images of objects at at least two different distances from the objective, there being arranged at one focal plane of the objective a corrective element divided into at least two fields in which the refractive power differs between them. |
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DETAILED DESCRIPTION One object of the present invention is to produce a photographic objective, which is of particular use in moving picture and TV-cameras, making it possible in a single scene to provide sharp images of two objects at different distances, i.
e.
, each with its own depth of field.
The image thus combined should have a natural appearance, and if two different optical systems are used, it is particularly important that the unsharp image of one object made by the system which makes a sharp image of the other object, disrupt the sharp image of the other system as little as possible.
Otherwise, the unsharp image could create a visible ghost image.
If, however, the fuzzy image is of the same size as and is superimposed on a sharp image, the image will be perceived as sharp.
It is previously known to achieve this purpose by using two different objectives and mirror devices.
Major mechanical stability problems are encountered in this case, however.
Furthermore, it is difficult to make two images coincide exactly, one with a sharp object A and an unsharp object B and the other with an unsharp object A and a sharp object B.
The two images of A, one sharp and one unsharp, must be superimposed on each other even if they do not lie in the center of the image surface, which means that the objective must provide the same magnification.
One purpose of the invention is to achieve such a consolidation of images, and to do this with a single objective, suited to photography, cinematography, TV, etc.
The objective revealed by the above-mentioned patent specification does not constitute a solution to the problem according to the invention.
Two objects A and B at different distances will each be sharply imaged in individual halves by the known objective and be of the same size, but at the same time the unsharp images will be of different sizes, and therefore an unsharp and different-sized image of A, for example, will be superimposed on the sharp image of A.
This will have a very disturbing effect in a cinematographic picture, for example
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Optical Systems 
