Lens system

[Detailed Description of the Invention]

[Industrial Application] The present invention relates to the lens system which consists of combination of an optic axis, the radial type heterogeneous lens from which a refractive index changes perpendicularly, and a diffracted type lens. [Description of the Prior Art] It is indicated, for example to Abrideoptics, the 21st volume, and 993 page ~ that the radial type heterogeneous lens from which a refractive index changes to an optic axis and a perpendicular direction has very high Yield difference amendment capability. It is shown in this literature using the radial type heterogeneous lens that small or it can constitute the standard lens for cameras which was formerly six-sheet composition from two lenses. the distance of the direction where an optic axis and refractive-index distribution of a radial type heterogeneous lens cross at right angles -- the refractive index in the place of y and radius y -- the refractive index on n (y) and an optic axis (base) -- No and a distribution coefficient -- N and N2. -- if ... the following formula % type % A radial type heterogeneous lens denoted by the above-mentioned formula has a different target coefficient for every wavelength. When a sign of a wavelength will be put like N and d and a coefficient to each wavelength will be expressed, a number is expressed as follows to Ara showing distribution. Vl=Nra/Among the above-mentioned ((Ntr N1c) i=1.2. ...) Abbe numbers, when Vl bends light by a medium, it will mean about what chromatic aberration occurs. Abbe number [ of a base ] ■. It is expressed with 2 of Is the next. Vo"(Noa 1) / (NOF N0C) [Problem(s) to be Solved by the Invention] One of the high Yield difference amendment capability which a radial type heterogeneous lens has is the amendment capability of a chromatic aberration. Axis top chromatic aberration PAC which occurs with a radial type heterogeneous lens is given by the following formula. PAC= (-y %[/n ]'1lk) (phi) l/V O+phi, /V, (i) however y, Is the ray quantity, the angle of the light after n'o comes out of a lens system, and phi□ are the refracting power in a field, and the refracting power in phi and Is the medium. In order to demonstrate chromatic aberration capability with a radial type heterogeneous lens for t minutes, it is necessary to make small the value of (phi, 4/v0+phi, /v) of the formula (i). It will be whether vl has a large value or a negative value. When this vl is a small value, it turns out that a big axis top chromatic aberration occurs from formula (i). However, it is known that the easy material of manufacture will actually take the positive small value whose vl is about 10~30. Re or To since it is a grade of the above [ the value of radial type heterogeneous lens material v1 actually manufactured by the ionic exchange method etc. until now ]. The above-mentioned contents are indicated also in articles, such as the 25th volume of Abrideoptics, and 3351page~ (1986). Therefore, a chromatic aberration is thick when the easy radial type heterogeneous lens of manufacture is actually used (there is an occurring fault.). [A useless means to solve a subject] The lens system of the present invention is for solving the above-mentioned subject, is a lens system which combined the radial type heterogeneous lens from which a refractive index changes in the direction perpendicular to an optic axis, and the diffracted type lens, and satisfies the following conditions (1) and (2). Q) V, <V. (2) 0.01<sigmaphitl/sigmaphi. The refracting power of a radial type heterogeneous lens and φ Ah are the refracting power of a diffracted type lens <1., the Abbe number take out and according [ vo ] to the secondary coefficient of the Abbe number of the base of a radial type heterogeneous lens, V, and a Is radial type heterogeneous lens, and phi 6. In the present invention, in order to make a lens system into what has high implementability, the radial type heterogeneous lens with which it is satisfied of the above-mentioned conditions (1) was used. Production of a material will become difficult if this condition (1) is not satisfied. Especially the thing for which the material of big deltan is produced is remarkably difficult. deltan is the maximum refractive-index difference of the radial direction of a radial type heterogeneous lens. The range of vo is usually 25~70 in the Abbe number of a base as mentioned above. Conditions (+) are satisfied, and if the value of V, is smaller than the value of this vo, a very big axis top chromatic aberration will occur so that it may be formula-(i)-cut and may cut. When it is going to amend this chromatic aberration in combination with other lenses, at least 2~3 lenses are newly needed, the lens composition number of sheets in the whole system increases, and there is no meaning which introduced the radial type heterogeneous lens. Therefore, in the present invention, in order to amend the above-mentioned big axis top chromatic aberration by other methods, the diffracted type lens was introduced. It has a concentric circular pattern and the operation as a lens is obtained by the diffraction phenomena of light as the diffracted type lens is indicated, for example in articles, such as 27th volume of Abrideoptics 2960 pages etc. ('1988). According to this literature, it is shown that the diffracted type lens has the axis top chromatic aberration amendment capability at -3 and 45 for an Abbe number to be very big. Thus, when applying a diffracted type lens to the lens system using a radial type heterogeneous lens, it is preferred to satisfy the above-mentioned conditions (2). It is for this condition (2) amending an axis top chromatic aberration satisfactorily, and if a minimum is exceeded, the power of a diffracted type lens will be too small, and chromatic aberration amendment will become insufficient, If a maximum is exceeded, the power of a diffracted type lens is too large, and since a chromatic aberration becomes overamendment, and also the pitch of a diffracted type lens becomes fine too much and production of a diffracted type lens becomes difficult, it is not desirable. When actually combining a diffracted type lens and a radial type heterogeneous lens by the present invention, it may arrange as another object, respectively and may constitute a diffracted type lens on the refracting interface of a radial type heterogeneous lens again. Although the example which combined the diffraction grating with the heterogeneous lens is described in JP,2-83228,A, this diffraction grating does not have a lens operation. If the present invention described above contains a radial type heterogeneous lens and a diffracted type lens like the example shown later, it is clear that its it may be valid also to the lens system containing a homogeneous lens. [Example] Next, each example of the present invention is shown. As shown in Drawing 1, on the refracting interface by the side of the image of one radial type heterogeneous lens in which both sides consist of planes, Example 1 is what constituted the diffracted type lens, and has the following data. 7=Honorable; 10,000 f =20.0 F/2.0 rI=ol) d+=10.On and = -- heterogeneous -- lens r2 degree dz=o, o n2= diffraction type lens r 3= 1.028 X 106 (heterogeneous lens coefficient) NON N2 d line 1.72151 -0.21629 x 10-20.17860 x 10-10-5C, 71436-0, 21269x20-20.17860xlO-5F line 1.73904-0.22471x10-20.17860xlO-5v029.23460nu, 0. More Than 18000X102N3 is 0φ Ah-0,010. phi = 0.041, deltan =0.053 sigmaphiD/sigma phi = 0.24, however rl+ ... The curvature radius of lens each field, d, ... the thickness of each lens, an air interval, and nl+ ... the refractive index of each lens, and nu1. ... of the Anbeh chip box type lens of each lens is equivalent to a lens with a virtual, very high refractive index as shown also in literature 5PIE, the 126th volume, and 46page~ (1977). Therefore, in data, it was considered as the optically equivalent lens including the Yield difference etc. which generate a diffracted type lens, and the value of the curvature radius r, thickness d, refractive index n, and Abbe number nu was shown. In the example in a way, the refractive index of a diffracted type lens and an Abbe number are n = 10001 and Sea- 3 and 45. The diffracted type lens indicated other examples similarly. The spherical aberration of this example is as being shown in Drawing 2. The spherical aberration of the lens of the following data which does not use the diffracted type lens by the same spec. as this example is as being shown in Drawing 3. Ho watcher bro!=t!= f= 20.0 F/2.0 rlooO d+=10.On1= heterogeneous lens r2=omega (Heterogeneous lens coefficient) N, N, N2d line 1.72151 -0.26321xlO-"0.19674xlO-'C line 1.71436-0.25882X10-20.19674xlO-5F line 1.73904-0.27345x10-20.19674xlO-'vo29.23460 v+ Three or more 0.180 CIOXIO"N is 0. phi = 0.050 and deltan =0.065 -- the refracting power which a radial type heterogeneous lens shares since this diffracted type lens shares a part of real Flexural force of the present invention which combined the heterogeneous lens and the diffracted type lens so that clearly from these Drawings 2 and Drawing 3 is small, and ends Since deltan to need can be made small, it is very advantageous on material production. A diffracted type lens may not be formed on the plane of a radial type heterogeneous lens in this example, but a diffracted type lens may be formed on other parallel plates, and a radial type heterogeneous lens may be combined with this. Although this diffracted type lens gives the operation as a spherical lens, if the operation as an aspheric surface lens is given, control of a Yield difference will become easy. Example 2 is the composition shown in Drawing 4, is Radical of two sheets and has the following data. Just a remembrance f= 50.0 F/1.8 The maximum image quantity 21.6, half-field angle 23.5 *r+= 74, 9949d I-0, 0000 n, - diffraction type lens r 2 = 74, 9963dz=10.6527 n2-heterogeneous lens r, and =25.8762d 3=3.5915 r4=Oo (iris diaphragm) d= 7.2551 r s =-38, 8562 (Is-9-4755rl, - heterogeneous 1 / 7 A r b =-47-9843 d 6=0.0000 n 4-diffraction type lens r 7 =-47-9836 (heterogeneous lens coefficient)) Object side NOx+ d line 1.72151 -0.10428XIO-2C line 1.71436 -0.10254X10-2F line 1.73904 -0.10833xlO-2nu. 29.23460 Nu, 0.18000XlO2N2 Nl d line 0.91426X10-6-0.1.0385X10-9C line 0.91426X10-'-0 and more than l0385X10-9F line 0.91426x10-6-0.10385X10-9N4 are O image sides. NoN. d line 1.72151 -0.79260X10-3C line 1.71436 -0.77939X]0-"F line 1.73904 -0.82342xlO-3vo29.23460 Si, O,]8000X102N 2 ' N : 1d line 0.51028X10-'-0 and 33306X10-9C line 0.51028X10-'-0 and 33306X10-9F line 0.51028xlO-'-0, 33306xlO-9phio -0,002, 0,003 phi =0.022, 0.015deltan =0.170 0.160sigmaphi, /sigmaphi. = 0.14 -- the Yield difference situation of this example is as being shown in Drawing 5. . The Yield difference situation of the lens system of the following data where a diffracted type lens is not used by the same spec. as this example is as in Drawing 6. # Accelerated Rumo= f= 50.0 F/1.8 the maximum image quantity 21.6, half-field angle 23, 4 *r, and =75.1095d+ = 10.6560 n = -- heterogeneous -- lens r 2= 25.0620 d 2=3.6000 r3=■ (iris diaphragm) d3=7.0298 r -- 41-0685 d =9.4642 n 2-heterogeneous lens r and =-45-7069"# I ->Postcode<-->/ (Heterogeneous lens coefficient) Object side No N. d line 1.72151 -0.12526X10-2C line 1.71436 -0.12317X10-2F line 1.73904 -0.13013X10-2nu. 29.23460 Nu, 0.18000X102N Z N N d line 0.10905X10-5-0.43448X10-9C line 0.10905x10-5-0.43448X10-9F line 0.10905 X 10~5-0.43448X10-" -- the image side N o N + d line 1.72151 -0.81124X10-'CvAl and 71436 -0.79772X10-' F line 1.73904 -0.84279X10-3■. 29.23460 V 0.18000XlO2N2 N3 d line 0.43705X10-'0.40694xlO-"C line 0.43705X]0-'0140694 X 10- "F line 0.43705X10-'0.40694xlO[ - ]" phi, = 0.026 and 0.015deltan =0.207 0.157 -- by using a diffracted type lens like [ this example ] Example 1, the axis top chromatic aberration has become small sharply, and it can make required deltan small. It is the same as the case of Example 1 to also use a diffracted type lens as another object also in this example and that an aspheric surface operation can be given to a diffracted type lens possible. Example 3 is as being shown in Drawing 7, and the radial type heterogeneous lens in which one field is a plane, and it are the lens systems which combined independently what constituted the diffracted type lens on the parallel plate, and it has the following data. !=!=!=!= Mi 7 f= 20.0 F/2.0 r+=40.0 d+=10.o nl-heterogeneous 1 / 7 A T2-degree(X)d2=4.0 r3=■ d3=1.0 n 2=1.51633 v 2=64.15r4-omega da=0.o n, - diffraction type lens r s-4,866X 105 (Heterogeneous lens coefficient) N o N IN z d line 1.72151 -0.97620X10-'0.75332X10-' C line 1.71436 -0.93959xlO-'0.75332xlO-7F line 1.73904-0.10616X10-20.75332X10-7VQ 29.23460 V, 0. Three or More 80000X1ON is OphiD-0,021. phi =0.019 deltan =0.024sigmaphi, /sigmaphic, and -1.07 -- since this example used the diffracted type lens as another object with the heterogeneous type lens, manufacture of a diffracted type lens has an easy advantage. The Yield difference situation of this example is as being shown in Drawing 8. Example 4 is as being shown in Drawing 9, comprises two radial type heterogeneous lenses and a thing which constituted the diffracted type lens on the parallel plate arranged in the meantime, and has the following data. One 1 Wife Masahide÷ f =50.0 F/2.0 The maximum image quantity 21.6 and half-field angle 23.3 *r I=45.5254 d r = 10.1111n1 - heterogeneous -- lens r 2= 26.4833 d 2=3.2987 r 3 = 6.817 X 106 d s= 0.0000 n 2= diffraction type 1 / 7 A ra=omega d 4=1.0O00n 3=1.51633 Si 3=64.1rs= (1) d = 3.08i8 r 6--33.1799 d b = 12.3677 n 4 = -- heterogeneous -- Lens r 7 -- 55.4017 d and =1.0000 r6=OO (iris diaphragm) (Heterogeneous lens coefficient) Object side N o N IN z d line 1.72000-0.10326x10-20.23507xlO-'C line 1.71568-0.10264x10-20.23507xlO-'F line 1.73001-'0.10470x10-20.23507xlO-6v. 50.24424 V+ Three or More 0.50000 XlO"N is O Image Sides. N N N2 dvAl and 72000 -0.72643xlO-'0.34927xlO-6C line 1.71568-0.72207x10-30.34927XIO-6F line 1.73001-0.73660X10-30.34927xlO-6 Si. 50.24424 Si and More Than 0.50000X102N3 are OφAh=0.0015. phi = 0.020, 0.018 deltan =0.235, 0.083 sigmaphi. /sigmaphi, =0.039 Since this example also used the diffracted type lens as the non-Homonymy lens and another object, manufacture of a diffracted type lens has an advantage which becomes easy. The iris diaphragm has been arranged behind a lens system, the diffracted type lens has been arranged between two heterogeneous lenses, and one diffracted type lens has amended both the axis top chromatic aberration and the magnification chromatic aberration. The Yield difference situation of this example is as being shown in Drawing 10. [Effect of the Invention] In the present invention, a radial type heterogeneous lens and a diffracted type lens are combined. therefore -- using having made power share with a diffracted type lens, and its chromatic aberration amendment capability -- power of a radial type heterogeneous lens -- smallness (it carries out, and deltan is made small, and it is made a material which is easy to make again, and enables it to realize a lens system by which a Yield difference was moreover amended satisfactorily).

[Brief Description of the Drawings]

Drawing 1 is a sectional view of Example 1 of the present invention, and Drawing 2 is a Yield difference curvilinear figure of Example 1, Drawing 3 is a Yield difference curvilinear figure of the lens system which does not use a diffracted type lens with composition similar to Example 1, Drawing 4 is a sectional view of Example 2 of the present invention, and Drawing 5 is a Yield difference curvilinear figure of Example 2, In the sectional view of Example 3 of the present invention, and Drawing 8, the sectional view of Example 4 of the present invention and Drawing 10 of the Yield difference curvilinear figure of Example 3 of the present invention and Drawing 9 are [ the Yield difference curvilinear figure of the lens system which is not included for a diffracted type lens with composition with Drawing 6 similar to Example 2, and Drawing 7 ] Yield difference curvilinear figures of Example 4. * 8 A request people Olympus Optical Co., Ltd. representative Toward figure 1 of Kanji Drawing 2 Drawing 3 Drawing 5 Drawing 6 Drawing 7 Drawing 8