JPH0387805A - Wide-angle eyepiece lens - Google Patents

Abstract

PURPOSE: To provide a wide-angle eyepiece having a wide view and a long focal distance behind an injection pupil by arranging a divergent lens element, convergent lens element and multi-lens system convergent element successively from the side of half tone image to be formed and satisfying a specified conditional expression. CONSTITUTION: Concerning the wide-angle eyepiece composed of three lens elements arranged along an optical axis for a telescope having the wide view, especially, for a ground telescope, this eyepiece arranges a Galileo system composed of a divergent lens element GI and a convergent lens element GII and a multi-lens system convergent element S successively along an optical axis O-O' from the side of half tone image to be formed toward the eye and satisfies the conditions shown by expressions I and II. With this Galileo system, a virtual object is enlarged so as to form as a half tone image P' on a half tone image plane ZB and this half tone image P' is formed as an infinitely far image by that convergent system S.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a wide-angle eyepiece for a telescope with a large field of view, especially a ground telescope.

BACKGROUND OF THE INVENTION US Pat. No. 4,525,035 describes a six-member eyepiece for an 80° field of view. In the case of this eyepiece, the rear focal length of the exit pupil is too short compared to the focal length for comfortable viewing with the naked eye, especially for spectacle users. Also, U.S. Pat. No. 4,286,844 describes a seven-member eyepiece for a 90 DEG field of view, with one diverging lens element in front of the intermediate image.

This eyepiece lens has too much pupil aberration.

U.S. Pat. No. 4,720,183 describes an eight-member eyepiece for an 85° to 90° field of view. This eyepiece has good correction. However, this has the disadvantage that the eyepiece diameter is large and some of the lenses have an extreme shape, which makes the manufacturing costs very high.

A wide-angle eyepiece is described in East German Patent No. 263,606, in which a diverging cemented lens system is used in the direction from the side of the intermediate image to be formed to the eye;
A convergent cemented lens system, a biconcave lens, a concave-convex lens, and a weakly convergent cemented lens system are arranged. This eyepiece lens has the drawbacks of being large in weight and diameter and requiring complicated manufacturing technology.

Economic patent no. WP G02B73115526 describes a wide-angle eyepiece, in this case from the side of the intermediate image to be imaged towards the eye.

A diverging three-lens cemented system, a convergent two-lens cemented system, an aspherical biconvex lens, and a convergent meniscus lens are arranged. This eyepiece has the disadvantage that the back focal length of its exit pupil is too short for comfortable unaided observation.

(Problems to be Solved by the Invention) The object of the present invention is to eliminate various drawbacks in the prior art as described above, and to create a wide-angle eyepiece with a simple structure and a large field of view and a large back focal length of the exit pupil. That's true.

The object of the invention is to have an exit (l!) back focal length greater than 0.8 times the focal length of its eyepiece, the maximum free diameter of each lens being 2 times the diameter of its intermediate image to be imaged.
．． The object of the present invention is to provide a wide-angle eyepiece for a 90° rainbow of no more than 6 times, whose image distortion correction corresponds to the angular conditions, and whose Petzval sum is corrected.

(Means for Solving the Problems) According to the present invention, the above-mentioned problems can be solved in a wide-angle eyepiece lens consisting of a diverging lens element G1, a convergent lens element G1, and a convergent lens element G1, in order from the side of the intermediate image to be formed. A multi-lens convergent element GIlh and a multi-lens convergent element S are arranged under the following conditions: 1 Shirakawa to 15·f゛1 (However, in the above formula, each symbol is as follows: f°1=divergent element G , focal length '11 = focal length of convergent element Gfl 'I/1
1 = focal length of each element G or Gl+) is maintained.

[Effect]

The intermediate image to be imaged by this eyepiece, for example the rear intermediate image of a telescope objective, is the virtual object of this eyepiece. By means of the Galilean system, this virtual object forms an enlarged real intermediate image, which is imaged by the convergent multi-lens system as well as by an eyepiece.

In this case, for a field of view of 90', the Galilean system G consists of a divergent lens cemented system consisting of a diverging lens L1 and a convergent lens L2, and a biconvex lens L3, and the collective system S is A convergent lens consisting of convergent lenses 1 and 4, a diverging lens L5, a biconvex lens L6 whose surface facing the intermediate image to be formed is an aspherical surface, and a convergent meniscus lens L7. 2 in the sexual mating system
It is advantageous to have more. This lens structure is the Galilean G lens 1. , to the aspheric surface of lens L6, and thus making it possible that the free diameter of each lens does not become too large.

For balanced correction of image defects, reference should be made to the configuration data of claim 3 of the present application.

〔Example〕

The present invention will now be described in more detail with reference to the accompanying drawings.

FIG. 1 shows a Galileo lens consisting of a divergent lens element G and a convergent lens element G11, which are arranged along the optical axis 0-0° from the side of the intermediate image to be imaged toward the eye. The system and the principal planes and paraxial relationships of the convergent element S are shown. The virtual object is magnified by the Galilean system as an intermediate image P' on the intermediate image plane ZB, and this Po is imaged at infinity by the convergent system S. The chief ray for the field stop is shown in dotted lines.

Figure 2 shows the optical axis o- from the side of the intermediate image to be formed.
Along o', a divergent lens cemented system Kl consisting of a divergent lens L and a convergent lens L2 and a biconvex lens L
3, a convergent lens L4, a divergent lens L, t, a biconvex lens L6 whose surface facing the intermediate image to be imaged is aspherical, and a convergent lens A lens sectional view of a wide-angle eyepiece is shown in which a converging cemented system consisting of a meniscus lens L7 and a collecting system S of two are arranged.

A balanced correction of the various image errors is given in radians γ+, J
jXsdI, refractive index n1, Atsbe number ν. , the parameter a and the aspherical convex radius γ", each of the above lenses L
1 to I, 7 and the arrangement of the respective air gaps lk, where the arch height 2 of the aspheric surface depends on the distance gh to the optical axis according to the following formula, and each of the above values is: Table 1 shows the age.

Army 1 table f゛~1 1:6.25 2σ =900γ1
・ -: ], 3780 d, -0,+20 γ2- 1.7536 d2- 0.384 γ, -4,0492 1, -1,074 γ4~3.7872 da -0,520 γ, -12, 6900 1□ -1,751 γ6 praise 7.1594 d4 meeting 1.040 γ, -1,6887 d5- 0.192 γ8 ・-17,0216 +3- 0.016 γ9・ 1.6962 Aspherical surface a Snow - 0, (1015 d6- 0.840 γ1゜・-5,13Ki la = 0.0IFi γ1.- 1.5408 d?・0.480 γ, 2- 3.5792 1.68101 1.62410 1.73430 1.68101 1.79192 1.55440 1.55440 54.74 36.09 28.12 54.74 25.52 6:1.28 6:1.28

[Brief explanation of drawings]

FIG. 1 is a basic paraxial configuration diagram of a wide-angle eyepiece according to the present invention, and FIG. 2 is an explanatory sectional view of this wide-angle eyepiece. 0-0'... 1 on the optical axis, K2... Lens junction system Ll, L2, L3, L4, L5, L6, L7... Lens G... Galilean system S... Collective system 1k.・・Air gap AP・・Injection ○

Claims (3)

[Claims] (1) In a wide-angle eyepiece consisting of three lens elements arranged along the optical axis, in order from the side of the intermediate image to be imaged, a divergent lens element G_1, a convergent lens element G_1_1, and a multi-lens The system convergent element S is arranged, and the following condition is maintained, namely -f'_1_1/f'_1<0.7 |f'_1_/_1_1|=-15・f'_1 (However, in the above formula, each symbol is as follows f'_1=divergent element G_
1 focal length f'_1_1 = focal length of convergent element G_1_1 f'_
1_/_1_1=represents the focal length of each element G_1 to G_1_1). (2) In order from the side of the intermediate image to be formed, a diverging lens cemented system K_1 consisting of a diverging lens L_1 and a convergent lens L_2, a biconvex lens L_3, a convergent lens L_4, and a diverging lens L_5, a biconvex lens L_6 whose surface toward the intermediate image to be imaged is aspherical, and a convergent meniscus lens L_7. A wide-angle eyepiece according to claim 1, wherein the wide-angle eyepiece is arranged. (3) The eyepiece has the following characteristic values, namely ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ In this case, the arch height z of the above aspherical surface is the following formula ▲ 3. An eyepiece according to claim 2, which depends on the distance h from the optical axis to each point of its aspheric surface according to a mathematical formula, a chemical formula, a table, etc.