JP2913349B2 - Magnifying Magnifier Lens System and Magnifying Magnifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loupe for observing a virtual image of an enlarged observation object by placing an observation object near a rear focal point of a positive lens and bringing an eye closer to the positive lens from the opposite side. Lens system.

[0002]

2. Description of the Related Art A conventional loupe lens system has a so-called fixed focal length, so that when observing the same object at different magnifications, a lens system having a different focal length is provided. It is necessary to replace the loupe and observe again.

Before re-observing with another loupe in this manner, the user must first remove his / her eyes from the previously observed portion of the observation object, and then find the same portion again with another loupe. , It is time-consuming and inefficient.

A loupe usually forms a virtual image of an object with a lens at a distance of 250 mm for clear vision, and its apparent size and
Magnification is indicated by the ratio of the size when the object placed at a position of 250 mm is directly viewed with the naked eye. The magnification will vary depending on the positional relationship between the lens and the eye, but is generally represented by the ratio of 250 mm to the focal length of the lens,
A lens with a shorter focal length has a higher magnification.

However, a lens having a short focal length tends to have a small aperture, and it is difficult to obtain a visual field unless the eyes are brought close to the lens. Also, when the lens is thick, the distance between the rear end of the lens and the object becomes short, and there is a disadvantage that illumination is difficult to perform. For this reason, conventional loupes having a fixed focal length of at most three or four are often used.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to observe a part of an object at a different magnification while observing a part of the object to be observed, to temporarily remove the eye from the observed part and exchange the loupe, The purpose is to enable continuous observation without any search.

It is another object of the present invention to change the focal length of an observation object during observation without changing the position of the eye relative to the lens or the position of the observation object.

Another object is to facilitate means for illuminating an observation object.

[0009]

A lens system of a variable power loupe according to the present invention is a lens system composed of eight elements in five groups, wherein the first unit is L ₁ and the second unit is L ₁ from the eye side toward the observation object side. L ₂ ,
When the third group is L ₃ , the fourth group is L ₄ , and the fifth group is L ₅ ,
L ₁ is a positive lens with a strong convex surface facing the object side, L ₂ is two negative lenses with a strong concave surface facing the eye side, L ₃ is a cemented positive lens with a strong convex surface facing the object side, and L ₄ is when a biconvex positive lens, L ₅ is the origins than the positive laminated lens having a strong convex surface facing the eye side, the focal length of L ₁ to the focal length of f _1, L ₂ and -f _2, 0.4F ₁ By satisfying the condition of> f ₂ > 0.3f ₁ , L ₂ is moved along the optical axis, and when changing the synthetic focal length, the change of the rear focal position is minimized, and the object plane is fixed. This makes it possible to observe by observation.

[0010] In the lens system of the variable magnification loupe of another invention In the lens system of the variable magnification loupe, separating the positive lens L ₄ in two positive lenses, opposed a stronger convex surface together 5
None the group nine configuration, in which to perform zooming by moving the negative lens L _2.

[0011] The variable power loupe another invention In the lens system of the variable magnification loupe above, a mechanism for correcting the positional deviation of the combined focal caused by the movement of L ₂ by the movement of the L _1, zooming In this case, the diopter is always kept at a constant value.

[0012]

[Action] Place the observation object in the vicinity of the rear focal point of the fifth group L ₅ standing consists positive laminated lens having a strong convex surface facing the eye side, a positive lens having a strong convex surface facing to the observation object side close the eye first group front of L ₁ standing becomes to observe a virtual image of the enlarged observation object by the lens system.

When it becomes necessary to observe the same object while changing the magnification during the observation in this way, it is necessary to use two negative lenses with the strong concave surface facing the eye in the same state. the second group L ₂ which are, is to observe a desired magnification displaced back and forth.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. The lens system includes a first unit L ₁ , a second unit L ₂ , The third lens unit L ₃ , the fourth lens unit L ₄ , and the fifth lens unit L ₅ are composed of five lens units arranged along the optical axis.

The first unit L ₁ is a positive lens having a strong convex surface facing the object side, the second unit L ₂ is two negative lenses having a strong concave surface facing the eye side, and the third unit L ₃ is having a strong convex surface facing the object. Negative and positive 2 towards the side
Like laminated positive lens, a positive lens of the fourth group L ₄ is a biconvex fifth group and L ₅ is a positive lens of bonding two negative having a strong convex surface facing the eye side.

In this lens system, when the negative lens of the second lens unit L ₂ is moved in the direction of the arrow AL ₂ along the optical axis O, the composite focal length of the entire lens system changes. Becomes possible.

The focal length of this first group L ₁ and the second group L
By appropriately selecting the ratio of the focal lengths of ₂ , the back focus at the time of enlargement and that at the time of reduction can be matched. In the middle, the back focus becomes slightly longer and the diopter of the loupe becomes minus, but the change is small and can be kept within the range of the diopter adjustment ability of the eye.

However, since there is an individual difference in diopter, if the lens of the _first lens unit L1 is moved by a small amount along the optical axis O so that diopter can be adjusted, observing even a presbyopic eye with poor adjusting ability will not hinder observation. Does not occur.

[0019] When the now first group moving amount of L ₁ necessary to correct the deviation of the synthetic focal position caused by the movement of the second group L ₂ delta, first in conjunction with the movement of the second group L ₂ if one group L ₁ to a mechanism for moving only Δ the eye side, can always be kept constant diopter be scaled.

[0020] In this case, although the position of the eye is changed exactly since the first group L ₁ is moved, the amount at most 1
mm, and in the case of a loupe, unlike an eyepiece, the eye point is not fixed,
In practice, there is no need to change the position of the eye.

When the focal length of the first lens unit L ₁ is f ₁ and the focal length of the second lens unit L ₂ is −f ₂ , in order to reduce the movement of the focal plane and achieve the above object, the following is required. It is necessary to use a combination of lenses that satisfies the above condition. 0.4f ₁ > f ₂ > 0.3f ₁

If f ₂ is longer than 0.4 times f ₁ , the back focus in the case of a long focal length becomes short, out of the range of diopter adjustment, and conversely 0.3 times. If it is shorter than this, the back focus at the short focal length becomes too short, and is outside the range of diopter adjustment.

[0023] However in combination that are outside these ranges, if the structure for moving the first group L ₁ as described in claim 3, it is possible to eliminate the diopter change. However the amount of movement of the first group L ₁ is large, it is necessary to change the position of the eye in accordance with the magnification.

In the following, from the eye side to the object side, the radius of curvature of each lens is γi, the center thickness of the lenses and the distance between the lenses are di.
In the following description, the refractive index of each lens with respect to the d-line is ni, and its Abbe number is νi.

In the embodiment of FIG. 1 in which the fourth unit L ₄ is constituted by a single lens having a biconvex surface, the longest focal length f = 33.4 m.
m, d-line at the shortest focal length f = 16.6 mm, C
FIGS. 2 and 3 show the spherical aberration and the astigmatism with respect to the line and the F line. It can be seen that the image plane is extremely flat for a field of view of 30 degrees. Table 1 shows the data of this lens system.

[0026]

[Table 1]

The second lens unit L ₂ is moved in the direction of the arrow AL ₂ along the optical axis O to change the focal length, so that the first lens unit L ₁ and the second lens unit L ₂ and the second lens unit L ₂ and the third lens unit L 3 Center spacing d ₂ and d of group L _3
6 changes and the sum is kept constant at 11.7.

The reason why the back focal length does not completely match and the short focal length is slightly shorter than the long focal length is that the set position of the object is adjusted in consideration of the change in spherical aberration and in order to match the use conditions. 19. slightly shorter than the back focus
This is because the diopter is set at the position 7 and the diopter at the time of zooming is kept substantially equal at both ends. Despite first group L ₁ is fixed, the change in dioptric power is only up to 1.4 diopters.

Although the embodiment of the present invention has been described with reference to FIG. 1, the embodiment of the present invention is not limited to only FIG. 1, and the technical means may be partially changed and added within the scope of the present invention. It is also possible to carry out. For example the embodiment of Figure 4 a fourth group L ₄ in FIG. 1 partially changed, a construction of two example of dividing the positive lens.

The longest focal length of the lens system of FIG. 4 is 16.6 m.
FIGS. 5 and 6 show the spherical aberration and astigmatism with respect to the d-line, the C-line and the F-line having m and the shortest focal length of 8.21 mm, respectively.
Table 2 shows the data of the lens system.

[0031]

[Table 2]

[0032] while maintaining d ₂ + d ₆ at a constant value in the lens system of Example 1 in the same manner as FIG. 2 in FIG. 1, but by changing the magnification by moving the second group L _2, long and short focal length Back focus is the same value at both ends.

Although not separately illustrated as another embodiment, in the embodiment of FIG. 1 or FIG. 4, the distance d ₂ in the table is used instead of the distance d ₂ between the lenses of the first unit L ₁ and the second unit L _{2. If 2} + Δ is used, the middle back focus can be made equal to the value of 8.85 at both ends. That along with the movement of the second lens group L _2, by a first group of L ₁ to mechanism for moving Δ the eye side, it is possible to keep the diopter at a constant value, to claim 3 equivalent lens system Become.

[0034]

Since the present invention is as described above, the use of this variable magnification loupe lens system makes it possible to produce a variable magnification loupe having a magnification ratio of about twice.

Further, since the apparatus can be used without changing the position of the observation object and the position of the eyes, it is possible to change the magnification and the field of view while paying attention to the observation object.

Further, since the back focus at the time of the high magnification is longer than the focal length, there is an advantage that the illumination condition can be maintained well.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a lens system of a variable magnification loupe according to an embodiment of the present invention.

FIG. 2 shows the spherical aberration of the embodiment of FIG. 1 at the longest focal length,
It is an aberration curve figure showing astigmatism.

FIG. 3 is an aberration curve diagram showing spherical aberration and astigmatism at the shortest focal length in the embodiment of FIG. 1;

FIG. 4 is a configuration diagram of a lens system of a variable power loupe according to another embodiment.

FIG. 5 is an aberration curve diagram showing spherical aberration and astigmatism at the longest focal length in the embodiment of FIG.

FIG. 6 is an aberration curve diagram showing spherical aberration and astigmatism at the shortest focal length in the embodiment of FIG. 4;

[Explanation of symbols]

L ₁ first group L ₂ second group L ₃ third group L ₄ fourth group L ₅ fifth group

Claims (3)

(57) [Claims] In a lens system composed of eight elements in five groups, the first group is L ₁ and the second group is L from the eye side toward the observation object side.
₂ , when the third lens unit is L ₃ , the fourth lens unit is L ₄ , and the fifth lens unit is L ₅ , L ₁ is a positive lens with a strong convex surface facing the object side, and L ₂ is a strong concave surface with the strong lens facing the eye side. two negative lenses, L ₃ is origins than the positive laminated lens having a strong convex surface facing the positive lens of the lamination towards the object side, L ₄ is a positive lens of biconvex, L ₅ is a strong convex surface on the eye side, Let the focal length of L _{1 be} f ₁ , L ₂
When the focal length of −f ₂ is −f ₂ , by satisfying the condition of 0.4f ₁ > f ₂ > 0.3f ₁ , L ₂ is moved along the optical axis, and when the combined focal length is changed, A variable magnification loupe lens system that enables observation with a fixed object plane while minimizing changes in the side focal position. 2. A lens system as claimed in claim 1, to separate the positive lens L ₄ in two positive lenses, without the 5 group nine constituted opposed a stronger convex surface together, moving the negative lens L ₂ A loupe lens system that changes magnification by doing. 3. The lens system according to claim 1, wherein
The positional deviation of the combined focal caused by the movement of the _two provided a mechanism for correcting the movement of the L _1, magnification loupe always provided with a structure to keep the diopter at a constant value even if the magnification.