JPH02222914A - Wide-field ocular - Google Patents

Abstract

PURPOSE:To realize small distortion and the superior flatness of an image plane and to compensate the spherical aberration of the pupil of the eye by arranging a 1st lens group I and a 2nd lens group II so that their concave surfaces face each other, and reducing the Petzval's sum. CONSTITUTION:The ocular consists of the 1st lens group I which has positive or negative refracting power and the 2nd lens group II which has positive refracting power on the whole. Further, the ocular satisfies conditions shown by inequalities, where (f) is the focal length of the whole system, f1 the focal length of the lens group I, f2 the focal length of the lens group II, and d2 the gap between the lens groups I and II. Consequently, the high-eye-point wide-field ocular is obtained which has small distortion in aberration and image forming performance wherein the flatness of the image plane is superior up to the periphery of the visual field.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a wide field eyepiece.

[Prior Art] An eyepiece lens is a kind of magnifying glass, and therefore, it generally has a simple structure consisting of a combination of convex lenses. For this reason, the Petzval sum becomes a large positive value, field curvature remains, and distortion is often large. Therefore, in a microscope optical system, the objective lens and eyepiece lens tilt the image in opposite directions. However, the tilt of the image is not sufficiently corrected.To avoid this, the average image plane of the meridional image plane and the sagittal image plane is generally erected. This method is used to eliminate field curvature. A conventional example employing this method is, for example, a lens system disclosed in Japanese Unexamined Patent Publication No. 60-57315. However, in the case of this method, if the Petzval sum is large, the meridional image plane and the sagittal image plane will be separated, and astigmatism will not be sufficiently corrected.Furthermore, distortion aberration will be caused by However, the eyepiece lens has a larger amount of residual aberration than the eyepiece lens, and an eyepiece lens with distortion aberration well corrected is desired.

Furthermore, when the eye relief of the eyepiece is increased, the spherical aberration of the pupil may not be sufficiently corrected, causing vignetting at the periphery of the field of view, and further aberrations of light rays at the periphery of the field of view, especially coma aberration,
It is difficult to satisfactorily correct astigmatism and chromatic aberration of magnification.

[Problems to be Solved by the Invention] The present invention has small distortion aberration and excellent flatness of the image plane.
The object of the present invention is to provide a wide-field eyepiece with a high eye point in which spherical aberration of the pupil is also well corrected.

[Means for Solving the Problems 1] The wide-field eyepiece of the present invention comprises, in order from the light incident side, a lens group (1) having a positive or negative refractive power, and a second lens group (2) having a positive refractive power as a whole. II. Furthermore, the eyepiece lens of the present invention has a focal length f of the entire system,
When the focal length of the lens group I is f6, the focal length of the second lens group II is fz, and the distance between the lens group I and the second lens group II is d3, the following conditions (11, (2), f3)
It satisfies the following.

fil O, 8 < lf, l # fzl o, s < fz/f < 1.5 (31d,
<0.4f In the eyepiece of the present invention, the Petzval sum is reduced by arranging the lens group I and the second lens group ■ so that their concave surfaces face each other as described above6.The second lens group H is located on the object side. When configured with a cemented positive lens and a cemented lens, the overall aberration can be corrected in a well-balanced manner.

Condition +11 is a condition for achieving a high eye point, which is the object of the present invention, where the image plane is flat to the periphery of the visual field and off-axis aberrations are well corrected. In order to correct the Petzval sum, a positive or negative lens with a large focal length called a concave lens or a field flattener is used, but if the lower limit of condition fl) is exceeded, various off-axial aberrations will occur, mainly comatic aberration and astigmatism. The occurrence is thick (and it becomes difficult to correct this with a convex lens group).

Condition (2) is a condition for correcting off-axis aberrations while keeping the Petzval sum small for the light beam incident on the lens group (2). If the upper limit of condition (2) is exceeded, off-axis aberrations, especially coma aberration and astigmatism, cannot be corrected completely, and if the lower limit of condition (2) is exceeded, the flatness of the given image plane will be reduced as the Petzval sum increases. It will not be possible to secure it.

Condition (3) is a condition for properly correcting off-axis aberrations while keeping the Petzval sum small.

If the upper limit of condition (3) is exceeded, it becomes difficult to correct off-axis aberrations. In other words, the off-axis aberration generated in the first lens group deteriorates significantly when the light beam enters the second lens group II, and cannot be corrected by the second lens group II.

In order to properly correct off-axis aberrations while keeping the Petzval sum small, the following condition (4) is further required.

It is desirable to satisfy (5).

f41D>0.5f f5) 1ril>0.5f where D is the total thickness of the second lens group II, and r3 is the radius of curvature of the surface of the second lens group H closest to the object side.

If the lower limit of condition (4) is exceeded, off-axis aberrations, particularly astigmatism, generated in the lens group cannot be sufficiently corrected by the second lens group If.

If the lower limit of condition (5) is exceeded, it becomes extremely difficult to correct coma aberration in the second lens group II, and furthermore, pupil aberration deteriorates, so that correction of distortion aberration becomes insufficient.

[Example] Next, various embodiments of the wide-field eyepiece of the present invention will be shown.

Example 1 f=1 Eye relief 0.9354, Petzval sum 0.19
6r+ = -1,5061 dt"O, 0800 old = 1.60342 ν
=38.01ra=1.8615 d,=o, 1754 ra=-2,9414 d3;0.1202 Q,=1.75520
vx = 27.51r4 = 1.4799 d4 - 0.3304 n, = 1.60311
v, =60.70rs=-1,0382 ds=0.0120 rs=1.2453 da”0.3320 1”, knee 2.4484 d,=0.0120 ra=1.0943 d,=0.3600 r*=-0,9415 ds=0.1275 rho=1.3548 ・f, i=-1,37f D=1.2941f Example 2 f=1 Eye relief 0.9333 r+=-2,3337 d, = 0.0920 r2=1.7906 d, = 0.1000 rs −-3,5406 f, = 0.758f ni=1.60311 Qa= 1.74950 n, = 1.69350 n+=1.60342 ν, =50.81 νs =60.70 ν, :35.27, d*= 0.1754f -rs =2.9414f Petzval sum 0.363 ν, =38.01 jl, = 1.75520 d3= 0.0732 r4=1.1004 d4=0.3327 rs=-1,2958 ds=0.0114 rs=1.3526 d, =0.3600 rt=-1,8045 dt=0.0093 ra=1.1799 d, = 0.3680 r, = -0,8400 d, = 0.1082 rho = 2.7999 f+ = -1,67f [1 = 1.2628f Example 3 f=1 Eye relief 0.9194 r+ = 3.1183 f, = 0.789f.

ns” 1.56873 n, = 1.69680 Q, = 1.60311 ns” 1.74400 rs =27.51 = 63.16 = 56.49 = 60.70 = 44.73 d,=　O,if = 3.5406f Petzval sum 0.318 dl=0.0472 n+=1.57309 rz=1.1089 d, = 0.1934 r,=-t,7526 d, = 0.1149 r4=3.0777 d, = 0.3316 rs=-1,1674 d, = 0.0114 ra=1.6134 da"0.2178 rt”-2,6300 d, = 0.0093 rs=0.8182 d, = 0.2938 r,=-2,1155 ds=o, o(It◎ rho = 1.1201 f, =, -3,03f D=1.0698f 11: 1.75520 ns=1.603LL n4=1.69350 ns=1.62041 ns=1.75520 f, = 0.861f.

−rs= 1.7526f ν+ =42.57 ν, :27.51 ν, =60.70 ν, =50.81 ν, :60.27 ν, =27.51 d, = 0.1934f Example 4 f = 1 eye relief r r = -0,8247 d, = 0.112 r2 = = -0,88 d, = 0.152 ri = -1,3274 ds = 0.1272 ra = 1.1862 d, = 0.336 rs = -1,2249 d, = 0.008 ra = 1.5098 d, = 0.352 rt--2,4903 d, = 0.008 ".: 0.9711 ct, = 0.36 rs=-1,6913 0,852 Petzval sum 0.421 n, = 1.85026 =32.28 nz=1.834 =37.16 ns= 1.60311 =60.7 n<=1.8044 = 39 .58 n,: 1.48749 = 70.2 d, = 0.112 rho = 2.5876 f, = -221,34f, [, = 1.06f
, d, = 0.152fD = 1.3032f
, -r, = 1.3274f Example 5 f = 1 Eye relief 0.852 r, = -0,8075 d, = 0.2 rz = -0,88 d, = 0.152 r, = -1, 3876 d3 = 0.1272 r4 = 1.3096 d4 = 0.336 rs = -1,2455 d, = 0.008 ra = 1.5273 d, = 0.352 rt = -:3.1442 0.36 s , =23.78 ν, =32゜2B ν, =37.16 shi, =60.7 shi, =39.511 Petzval sum ns= 1.84666 fi+ = 1.85026 nz=1.834 1, 2 l , 50311 n, = 1.8044 d, = 0.008 ra = 0.8671 da" (1,36ns = 1.48749 v
s = 7[1,2r, = -2,5558 d, = 0.112 11. : 1.84666
v, = 23.78rho == 1.
7098 f,=42.973f, f,=1.129f
, d,=0.152fD" 1.3032f
, -ra= 1.3876f However, rho "
t, ”・+ r l O is the radius of curvature of each lens surface, d
,, d, ,..., r 9 is the wall thickness and air gap of each lens, nI-n! + ”-, n = refractive index of each lens 5ν
1. ν2°..., ν9 are numbers for each lens.

The aberration situations of these examples are as shown in FIGS. 6 to 10, respectively, which show the results of ray tracing from the eye side.

[Effects of the Invention] The eyepiece of the present invention is a high-eyepoint, wide-field eyepiece with small distortion and excellent image formation with flatness of the image plane up to the periphery of the visual field. In other words, the eye relief is close to the focal length, and the Petzval sum is the conventional via. This eyepiece is smaller than a point eyepiece with good image plane flatness, and the image plane flatness is significantly well corrected.

[Brief explanation of the drawing]

Embodiment 1 of the eyepiece lens of the present invention is shown in FIGS. 1 to 5, respectively.
6 to 10 are aberration curve diagrams of Examples 1 to 5, respectively. Applicant Olympus Optical Industry Co., Ltd. Agent Hiroshi Mukai Figure 2

Claims (1)

[Claims] In order from the light incident side, a first lens group having an overall positive or negative refractive power, and a second lens group having an overall positive refractive power.
It consists of a lens group, and the following conditions (1) and (2) are met.
), a wide-field eyepiece that satisfies (3). (1) 0.8<|f_1|/f (2) 0.5<f_2/f<1.5 (3) d_2<0.4f where f is the focal length of the entire system, and f_1 is the focal length of the first lens group. The focal length, f_2, is the focal length of the second lens group, and d_2 is the distance between the first lens group and the second lens group.