DE2001953C - Wide angle eyepiece - Google Patents

Description

The invention relates to a wide angle eyepiece for a Microscope with field lenses and eye lenses that are separated from one another by an air gap. In particular The invention relates to an ultra-wide-angle eyepiece with a high field number and a large S. Eye point distance.

In known wide-angle eyepieces, there is generally no light in the annular edge regions of the field of view, if not the spherical aberration of the image of the exit pupil of the eyepiece lens used at the point of the eye is sufficiently avoided. This is due to the fact that the diameter of the exit pupil of the objective is relatively small and that therefore the diameter the exit pupil at the eye point of the eyepiece is generally small. is made, in the On the order of 1 mm, while the field of view is very bright and therefore the diameter of the pupil of the observer is necessarily reduced, so that a failure of light in the annular edge areas of the field of view occurs even if there is little spherical aberration. It is therefore necessary to compensate the spherical aberration enough to avoid loss of light in the ring-shaped Avoid peripheral areas of the field of vision. »5

It is also necessary to position the field lens of an eyepiece * in front of the eye lens of the same at a suitable distance in order to catch the main rays emanating from the objective and to introduce them into the sleeve of the eyepiece, which b. has a limited diameter. Therefore, there is a tendency to make the eye point distance small in a wide-angle eyepiece. The eye point distance is generally sufficiently large if it is 6 mm, i.e. ii. exceeds the average length of a human eyelash. On the other hand, if the eye point position is too large, it is difficult for the observer to stably observe the image as a result of unsteady movements of the head. Therefore, the upper limit for the interpupillary distance should not exceed 20 mm. Therefore, it is believed that the appropriate interpupillary distance is on the order of 14 to 15 mm.
. When a wide-angle eyepiece is used together with a high-magnification objective in a microscope, it is necessary to give the eyepiece an over-correction of the chromatic aberration of the magnification in order to compensate for the under-correction of the chromatic aberration of the magnification of the objective.

The invention is based on the object of avoiding the disadvantages of known wide-angle eyepieces where the field lens is an achromatic cemented member that has positive refractive power, and the eye lenses Thick meniscus segment comprised of an anterior negative line and a posterior positive lens consists, where the cemented surface has negative refractive power and the front concave surface of the front negative Lens is directed towards the objective, and that further lenses of positive refractive power at a short distance are arranged behind the thick meniscus member.

According to the invention, this object is achieved in that the eyepiece has the following numerical data:

T d nd 1 Vd 1 161.0 1.5 1.6204 2 30.0 6.5 1.6259 60.3 3 -48.7 22.0 1 35.6 4th -51.9 1.8 1.7174 5 16.9 9.8 1.5891 29.5 6th -30.7 0.3 1 61.2 7th 30.7 3.5 1.5891 8th -240.3 0.3 1 61 ,? 9 15.0 3.5 1.5891 10 28.8 1 61.2 11th

Focal length F = 25.0

Field number = 26.0

Magnification - 10 times

Eye point distance E.P. = 14.6

The wide-angle eyepiece according to the invention has a large number of fields and a large interpupillary distance. It avoids light losses in the ring-shaped edge area of the field of view. Despite the simple construction it produces high quality images.

Since in the eyepiece according to the invention, the field lens element with achromatic cemented surface and positive Refractive power is provided as a whole, the chief rays emanating from the exit pupil of the with The objective used in the eyepiece comes in through the field lens element at a greater angle with respect to the optically; Axis are captured.

This allows a much wider area to be observed.
In order to compensate for the chromatic aberration of the enlargement as well as the distortion, the cemented surface of the meniscus member has negative refractive power. The use of the meniscus member is extremely effective for lengthening the eye point distance and at the same time for compensating for the field curvature of the eyepiece. The arrangement of one or more lenses with positive refractive power at a short distance behind the meniscus member is required to reduce the focal length of the eyepiece on one

Claims (1)

to hold a predetermined positive value. By condition 4: Providing such positive lenses can Astig- η 7 f < 1 <1 SF matism arising from the thick limb of the meniscus- ' ^{= 3 =} stirs, which is located directly on the front side of the positive where d ₃ eier air gap between the field lens lenses are compensated 5 member and the eye lens members. The kit radius r ₅ in the thick meniscus segment, d :; If the value of d _{3 is made} smaller than the difference in the refractive indices n _s - /; “between the limit described above, the ability to capture the principal anterior and posterior lens of the thick meniscus rays coming from the field lens member is the Difference in the number of _{Abbesciien vn 2} - vn ₃ at larger angles to the optical axis of the diverging between the front and rear lenses of the field eyepiece, insufficient. The refractive lens and the Li-it distance d ₃ between the field lens force for the chroma aberration of the magnifying lenses and the eye lenses also meet the following conditions: the eyepiece is deteriorated. Also approaching In this case, the image-side, in contact with the air U, -> r = r _s < 0.8 F leading surface of the field lens member of the ("s - n _e ) = 0.1 15 image plane of the lens. Therefore, damage appears 20 < (vn - ) cing or scratches, foreign parts or dust that ^{2 3} on the surfaces in contact with air 0.7FS d ₃ S 1.5F, sit, or small bubbles in the material that the Forms field lens elements in the field of view of the eyepiece. where F is the focal length of the total optical ao If, on the other hand, the value of d _{3 is} the System of the eyepiece. exceeds the upper limit, the The physical effectiveness of the above-described distance of the eye point, as the resulting four conditions shall be made in the following in detail - focal length of the eye lenses' ... a to be purified. must, in order to give the focal length of the eyepiece a predetermined Condition 1: to give 25th fixed value. 0 ^ 5 f < _r <08F ^ ' ^e invention is shown in the drawing. Hs indicates where F is the focal length of the eyepiece and r ₅ 6er Krüm- F i g. 1 shows a schematic longitudinal section through the inclination radius of the cemented surface in the thick meniscus segment arrangement of the lenses, is · 30 F i g. 2 to 6 different aberration curves of the in When the value of r _{5 is made} smaller than the FIG. 1 shown eyepiece. The lower limit defined above, ie smaller than F i g. Fig. 2 shows the spherical aberrations, where the 0.5F, the spherical aberration of the pupil grows, the solid line shows the aberration for the i / line, and the distortion is overcorrected. When on- The dashed line is that of the r-line. The line broken with the value of r ₅ above the above-described upper 35 point shows the F-line, while crossing the limit, the corrective power of the chromatic spherical aberration for the g-line is considerably doubled by the natural dissipation of the magnification Points broken curve is shown.
bad. F i g. 3 shows the chromatic aberration of condition 2: magnification,
(n - η)> 0 1 ⁴ ° F i g. 4 the astigmatism and the field curvature, * - '' during where / J ₅ and / ι, the refractive indices of the front F i g. 5 represents the distortion,
negative lens and the posterior positive lens are, as shown in Figs. 2 to 5, but which together form the meniscus member, and the cementation can be removed, the spherical surface has negative refractive power. 45 aberration is compensated extraordinarily well, while if the difference (/ J ₅ - n _e ) is made smaller the overcorrection of the chromatic aberration of the aU the lower limit defined above, i.e. magnification is passed on to the eyepiece, so smaller than 0.1, becomes the corrective force for the Ver. that the undercorrection of the chromatic But drawing, the chromatic aberration of magnification of the objective of the encryption ration in wesentgrcßerung as well as the spherical aberration of 50 loan, accurately compensated wi ^r d. Astigmatism pupil insufficient. as well as the field curvature is reduced within 3 mm over condition 3 · ^ as 6 ^anze · ^e 'd and reaches the field number 26. _ _Λ . . '. In addition, the distortion is _{reduced within 2% 20S (Vn 2} -VH ₃ ). where ν «, and vn _{3 are} the Abbe numbers of the front 55 F i g. 6 shows the spherical aberration of the pupil, and rear lens are that the positive field lens- The spherical aberration iit within about form a link with the achromatic putty surface. 1 mm reduced in the area of the field number 26, and the If the difference (vn _% - vn ₃ ) is made smaller, the loss of light in the ring-shaped P.and area of the than 20, the corrective power of the chromatic field is sufficiently avoided ir.t. The numerical Aberration of the magnification of the eyepiece «; insufficient. 6o aperture N.A. is 0.052 for field number 26. This This condition is fulfilled if the front one enables the numerical aperture to be reduced,
diffusing lens of the field lens member made of a glass is produced, which has a high Abbe number, claim: while the rear converging lens consists of a glass wide-angle eyepiece for a microscope with a is made with a lower Abbe number. 65 field lens member and eye lens members passing through This requirement is in contrast to the requirement that a greater air gap is separated from one another condition, the achromatic lenses with high positive are, wherein the field lens element is an achromatic tive refractive power. . Has a putty surface and as a whole has positive has strength and the lens elements of the eye contain a thick meniscus segment, which consists of an anterior negative lens and a rear positive lens, the cemented surface having negative refractive power and the front concave surface of the front negative lens is directed towards the lens, and that further lenses of positive refractive power are located a short distance behind the thick meniscus segment are arranged, characterized by the following numerical data: T d ltd 1 vd 1 161 1.5 1.6204 2 30.0 6.5 1.6259 60.3 3 -48.7 22.0 1 35.6 4th -51.9 1.8 1.7174 5 16.9 9.8 1.5891 29.7 6th -30.7 0.3 1 61.2 7th 30.7 3.5 1.5891 8th -240.3 0.3 1 61.2 9 15.0 3.5 1.5891 10 28.8 1 61.2 11 1 sheet of drawings