1. Field of the Invention
The present invention relates to an information processing system, and particularly to an information processing system for use in the design of a lens system.
2. Description of the Related Art
When an optical system is simulated by using an optical CAD (computer aided design) system, the data regarding the optical lens system should be defined in the CAD system as a matter of course.
The data with respect to the optical lens system that should be defined includes arrangement data such as the radius of curvature of a lens, the distance between lens faces, and the refractivity, which depends on the lens material simulated, and also includes evaluating position data such as the position of an object, and the evaluating image position.
With recent expanding applications of the optical technologies, various types of optical lens systems have been developed.
In the optical CAD system used for this purpose, it is required that various kinds of data associated with an optical lens system be easily defined in a manner which can fit with the actual development approach.
Taking a zoom lens as an example, a method of data definition with a conventional CAD system will be described below.
One known CAD system for such a purpose is the CAD system CODE-V, which is available from Optical Research Associates.
In this optical CAD system, the data associated with a zoom lens may be defined as follows:
(1) Input information on the evaluating light such as the wavelength, F-number, angle of view, and ratio of pupil diameter; PA0 (2) Input data representing the lens configuration such as the radius of curvature, the distance between lens faces, lens material, as well as the position and diameter of the diaphragm, which are associated with the respective lenses comprising the optical lens system; and PA0 (3) Evaluate positions such as the position of an object, and the evaluating position of an image.
In the case of an optical lens system of a camera, the position of an object and the evaluating position of an image correspond to the position of an object to be photographed and the position of a film plane, respectively.
Then, the data of the optical lens system that has been defined in such a way as described above is used as the reference data to represent the standard conditions for describing a plurality of conditions, i.e., the zooming condition in this case, of the optical system. In this definition, the lens faces whose positions are variable are specified by their numbers, and variable parameters are used as the face distances belonging to respective lens faces.
In this optical CAD system, data regarding the evaluating positions such as the position of an object and the evaluating position of the image can be defined such that only one common set of the data need be given for all optical lens system conditions.
In another known optical CAD system called OPTEDGE, which is available from Minolta Camera Co., Ltd., data regarding evaluating positions such as the position of an object and the evaluating position of the image can be defined such that one set of the data may be given separately for each optical lens system condition.
In this system, as in the CODE-V system, initial input data regarding the optical lens system is used as the reference data representing the standard conditions, and based on this reference data, a plurality of conditions, i.e., the zooming condition, of the optical system can be defined in such a way that the lens faces whose positions are variable are specified by their numbers, and the variable parameters are used as the face distances belonging to respective lens faces.
The position information of the optical system represents the vertex position and the inclination of each lens face of respective optical elements which comprise the complete optical system.
When an optical system that is decentered is designed using a conventional simulation system, the arrangements of the optical elements should be given for each lens face by defining its 3-dimensional location and its inclination and the like.
Referring to FIG. 47, one example will be described below.
In the optical system shown in FIG. 47, the coordinate of a face vertex (solid dots along the axis in FIG. 38) should be given for each face to define the position data of each optical element.
In this figure, the origin of an absolute coordinate system is assigned to (0,0,0) corresponding to the face vertex of lens face 1. However, the origin can be assigned to an arbitrary position.
More specifically, each arrangement of lens faces 1 through 13 is described by using 3-dimensional coordinates in the absolute coordinate system (the coordinates seen from the face vertex of the face 1). It will be a very troublesome task for a user to input the data after calculating the 3-dimensional coordinates for all faces ((x2, y2, z2), . . . , (x13, y13, z13)).
Furthermore, as various kinds of optical systems have appeared, decentered lens systems become used more often, and it becomes desirable for a simulation system to include 3-dimensional information.
When a decentered optical system is designed with a conventional simulation system, the origin, the inclination of the coordinates, and the rotation data should be given for each lens face.
In conventional techniques, there are no simulation systems in which a plurality of lens faces are combined into one unit so that the unit has information representing the decentering.
Yoshinari Matsui describes in his book entitled "The Design of a Lens System" that the development of a lens is an approach to establish design specifications which generally define conditions of performance or dimensions that the optical system should meet.
The first step of this approach is to review previously developed optical systems that are similar to the optical system to be developed. From the conclusion of the review, a basic design is established and the target performance and the type of lens are determined. Then, the power arrangement is determined for the optical lens system by means of approximated calculation.
While maintaining the determined power arrangement, the configuration is then determined as a thin-walled lens system in which the optical system is composed of lenses whose thicknesses can be neglected compared to the refractivity-dependent radius of curvature.
Then, thicknesses are introduced in the configuration which has been determined as the thin-walled lens system and thus specific shapes of the lenses are determined. The design of a lens is carried out according to such a procedure described above.
The determination of the power arrangement is an approach carried out to satisfy the design specifications by regarding the total optical lens system as a combination of a plurality of optical subsystems and by determining the power of the individual optical subsystems and the distances between the principal points of the optical subsystems.
In the designing of a lens system, it is important to determine the specific shapes of the individual optical subsystems without breaking the power arrangement. To this end, an optical CAD system is used to evaluate and investigate the optical system, and to determine the specific shapes of the lenses.
A zoom lens is an optical system in which the focal length of the total optical lens system can be continuously changed without changing the position of the image point, by changing the distance between the principal points of optical subsystems along the optical axis.
The distances between respective optical subsystems, which were determined when the power arrangement was determined, correspond to the distances between principal points of respective optical subsystems in the actual configuration.
Referring to FIG. 41 and 42, the distance between optical subsystems 1 and 2, which was determined during the power arrangement, corresponds to the distance between the image-side principal point of optical subsystem 1 and the object-side principal point of optical subsystem 2 in the actual configuration.
As a result, if a zoom lens system is defined in an optical CAD system according to a conventional method of inputting the data of an optical lens system, a variable parameter is not given as a distance between optical subsystems as described above, but it is necessary to specify the numbers of the lens faces whose distances are to be varied and it is necessary to define a variable parameter as a distance between faces that belong to the face.
Therefore, to determined a specific shape of a lens, the position of the principal point in this specific shape of the lens should be calculated and the parameter representing the distance between faces belonging to the face should by determined by specifying the number of the lens face to be varied. Thus, a very troublesome task is required to define the data of the optical system in an optical CAD system.
Furthermore, because only one object position can be defined for one condition of an optical lens system, if an optical evaluation for different positions of the object is required for a certain focal length of the optical lens system, the data should be defined separately for each condition of the optical lens system corresponding to each object position. As a result, for each given object position, a condition should be calculated in which focusing is adjusted depending on the position of the object so that the conjugate plane with respect to the object position may coincide with the evaluating position of the image. Then, the number of the variable face to be varied for focusing should be specified and the distance between faces belonging to the face should be given as the result that was calculated in such a way as described above. Unless such a very troublesome task is carried out, the desired evaluation cannot be accomplished.
For example, to define the respective conditions shown in FIGS. 43 and 44, the data representing each condition of the optical system should be separately given to perform an optical evaluation.
FIG. 43 shows a condition of an optical lens system where focusing is adjusted to an infinite object position. FIG. 44 shows a condition of the optical lens system where focusing is adjusted to an object position which is 20 cm distant.
In the case of an optical lens system of a camera shown in FIGS. 45 and 46, to make an optical evaluation of this optical system with respect to the two different positions of an object to be photographed, i.e., infinite and short distance positions, a focusing condition should be calculated in which the conjugate plane of the object position may coincide with the evaluating position of the image, i.e., the image is in focus, and then the data should be input separately for each of two conditions so that the data may represent the conditions shown in FIGS. 45 and 46.
In the case of the optical system shown in FIGS. 45 and 46, focusing is carried out by moving the position of the lens that is first when counted from the object side.
In some cases, an optical system comprises a large number of lens faces such as a few tens of lens faces, and it would be a very troublesome task for a user to input position data for each face, and input errors would often occur. Even if only a portion of the data representing the 3-dimensional positions of the respective faces of a group of optical elements is different, the data similar to each group would have to be input repeatedly.
To determine the spatial location for each lens face of a decentered optical system for each of the different zooming conditions, a memory area should be designated for the spatial locations corresponding to the number of different zooming conditions for each of the lens faces, which requires an unnecessarily large memory capacity. Thus, if a large number of zooming conditions are required, then the memory area for spatial locations should be expanded.