JPH06100724B2 - Microscope illumination optics - Google Patents

Description

TECHNICAL FIELD The present invention relates to a telecentric illumination optical system for illuminating a sample of a microscope, and more particularly to an illumination optical system capable of changing an illumination area corresponding to a magnification of a microscope. is there.

<< Prior Art >> As an illumination optical system of this type, as shown in FIG.
The one shown in FIG. 12 is known (Japanese Patent Application Laid-Open No. 56-165111).

This is a Keller illumination telecentric to the irradiation surface P of the microscope by arranging a condenser lens L _C and a relay lens L _B consisting of a collector lens L _A and a plurality of lenses L _B1 and L _B2 sequentially from the light source S side. System, relay lens L _B
By displacing each of the lenses L _B1 and L _B2 constituting the above along the optical axis, the illumination area P _A of the irradiated surface P can be changed according to the magnification of the microscope.

It should be noted that FIG. 10 shows a case where the magnification of the microscope is high, FIG. 11 shows a case where the magnification is intermediate, and FIG. 12 shows a case where the magnification is low, showing the state where the illumination area P _A changes. ing.

<< Problems to be Solved by the Invention >> In the above-mentioned conventional example, the relay lens L _B has a convergent lens L _B1 and a divergent lens L _B that are relatively movable along the optical axis.
_B2 and Manzanillo One and is configured, for an image S ₁ of the light source S so that formed between the convergent lens L _B1 and the condenser lens L _C, the following problems are pointed out.

I. It does not allow zooming with the pupil position fixed. Therefore, for example, even if perfect Keller lighting is established when the magnification is high (Fig. 10), other low magnifications (Figs. 11 and 12)
The Keller lighting is broken.

B. Moreover, accompanied connexion light source image on the zooming relay lens L _B
Since the position of S ₁ fluctuates, it is not possible to place the aperture stop at the position of the light source image, and if it is forcibly placed, the structure becomes complicated and the cost increases.

C. Generally, the light distribution intensity of the light source depends on the exit angle,
If the effective area of the light source is constant, it is desirable that the acceptance angle 2θ of the light flux emitted from the light source is small. Especially in a so-called epi-illumination system, since the entrance pupil of the objective lens usually becomes smaller as the magnification becomes higher, the effective usable area of the light source also becomes smaller as the magnification becomes higher. If the area of use of the light source can be increased even if the size is reduced, the amount of light can be effectively used. However, the above-mentioned conventional example does not take such a consideration.

The present invention is based on the above a. B. The items described in C are the technical issues to be solved.

<< Means for Solving the Problems >> The present invention is to solve the above problems and is configured as follows.

That is, a collector lens, a relay lens, and a condenser lens are sequentially arranged from the light source side to form a telecentric Keller illumination system with respect to the illuminated surface of the microscope, and a plurality of lenses forming the relay lens are moved relative to each other. In this way, in the illumination optical system of the microscope in which the illumination area of the illuminated surface can be changed according to the magnification of the microscope, the collector lens is configured with a telecentric optical system on the exit side and the relay lens is incident. It is characterized in that the optical system is telecentric on the light emitting side and the light emitting side and is variable in magnification.

<< Operation >> In the present invention, since the relay lens is configured to be capable of zooming with zooming while maintaining a telecentric relationship on the incident side and the exit side, light source images formed in front of and behind the relay lens. The position of does not move.

That is, even if the relay lens is zoomed, a telecentric and complete Keller illumination system is maintained with respect to the illuminated surface of the microscope.

Further, in a general case where the size of the entrance pupil of the objective lens changes depending on the magnification, as in a so-called epi-illumination system, it is possible to zoom the relay lens under limited conditions. Therefore, it is possible to make effective use of the light quantity by setting a small capture angle of the light flux emitted from the light source and setting a large effective use area of the light source.

<Example> An example of the present invention will be described below with reference to the drawings.

1 to 3 are diagrams schematically showing an illumination optical system according to the present invention. FIG. 1 shows a case where a microscope (not shown) has a high magnification ratio, and FIG. 2 shows an intermediate magnification ratio. In this case, FIG. 3 shows the case where the enlargement ratio is low.

This illumination optical system is a collector lens sequentially from the light source S side.
L _A , a relay lens L _B, and a condenser lens L _C are arranged to form a telecentric Keller illumination system with respect to the irradiation surface (sample mounting surface) P of the microscope, and the relay lens L _B
By relatively moving the plurality of lenses L _{B1 to} L _BN constituting the lens along the optical axis Z, the illumination area P _A of the irradiation surface P can be changed according to the magnification of the microscope. There is.

The above-mentioned collector lens L _A is the two groups of convergent lenses L _A1 and L _A2.
And is arranged so as to form a telecentric optical system on the exit side.

The relay lens L _B is composed of a plurality of lenses L _{B1 to} L _BN as described later.
Are arranged so as to be relatively movable along the optical axis Z, and are configured to form a telecentric optical system on the incident side and the emitting side. That is, the secondary light source side S ₁ formed at a predetermined position
Image (third light source image) S ₂ is formed at a predetermined position.

The condenser lens L _C is composed of a converging lens, and the above-mentioned third light source image is formed at the focus position on the light source side of the condenser lens L _C.
S ₂ is formed, and the irradiated surface P is arranged at the focal point on the sample side.

1 to 3, reference numeral Q ₁ is a field stop, Q ₂ is an aperture stop, and Q ₃ is a stop corresponding to the entrance pupil of the condenser lens L _C.

In the above embodiment, the relay lens L _B is capable of zooming by zooming while maintaining the telecentric optical system on the entrance side and the exit side, and each light source formed at the front and rear focal positions of the relay lens L _B. The positions of the images S ₁ and S ₂ do not move, and a perfect Keller illumination system is always maintained with respect to the irradiation surface P of the microscope. The effective use area S _A of the light source S also changes according to the size of the illumination area P _A.

Further, since the positions of the light source images S ₁ and S ₂ do not change, the field stop Q ₁ , the aperture stop Q ₂ , and the stop Q ₃ corresponding to the entrance pupil of the condenser lens L _C may always be fixed and movable. The structure can be simplified as compared with the expression type.

FIG. 4 is a schematic diagram showing a case where the irradiation optical system is used in a so-called epi-illumination system. In this figure, the same components as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 4, reference numeral 1 indicates the entire microscope, and reference numeral 2 indicates the entire illumination optical system. This microscope 1 has an objective lens
And L _1, consists imaging lens L ₂ Prefecture, the objective lens L _1, an irradiated plane P of the sample that is the measuring object on the rear focal position as viewed from the light source side is disposed, the imaging lens L ₂ , The image plane P ′ is arranged at the rear focal point when viewed from the sample side.

Then, the light flux emitted from the relay lens L _B is taken into the microscope 1 via the half mirror M arranged between the objective lens L ₁ and the imaging lens L _2, and is irradiated via the objective lens L _1. It is configured to illuminate the plane P.

That is, in this case, the condenser lens L _C of the illumination optical system 2 also serves as the objective lens L ₁ of the microscope 1.

FIGS. 5 to 7 are for explaining the action of the relay lens L _B when the objective lens L ₁ in the illumination optical system 2 is switched from the one for low cultivation rate to the one for high magnification. FIG.

Similar to FIG. 1, FIG. 5 shows a case where the magnification of the microscope 1 is high. That is, when the objective lens L ₁ is switched from the low-magnification one to the high-magnification one, the size of the entrance pupil Q ₃ is the same between the both objective lenses.

Similarly to the above, FIG. 6 shows that, when the objective lens L ₁ is switched from the low-magnification one to the high-magnification _one , the entrance pupil Q ₃ of the objective lens L ₁ also generally becomes small. Area S _A
It is a figure which shows that also becomes small.

FIG. 7 is a diagram showing that, by zooming the relay lens L _B in FIG. 6, the effective use area S _A of the light source S can be increased and the angle of light capture 2θ from the light source S can be reduced. .

This means that assuming that the light distribution intensity of the light source S is not actually uniform, the effective use area S _A is large and the capture angle 2θ is large.
The smaller the value of, the more the amount of light actually increases.

In addition, when the light source S is changed, it means that the illumination system can be configured under optimum conditions such that the size of the light source S matches S _A with the required illumination area P _A of the illuminated surface P. To do.

To actually realize such a relay lens L _B is possible, the following describes an example of such a relay lens L _B.

FIG. 8 is a schematic diagram for explaining the principle of the relay lens L _B used in the present illumination optical system, and a single lens is used here for the sake of simplicity. As shown,
_Set the focal lengths of the first, second and third lenses L _B1 , L _B2 and L _B3 to 1 respectively.
Assuming that an object is placed 50 in front of the first lens L _B1 with 00 and each lens interval being 100, the third lens L
_An image is formed at a position 50 behind _B3 , and the image forming magnification is 1.

Now, when the second lens L _B2 is moved backward (on the direction of the third lens L _B3 ) 10 on the optical axis as shown by the broken line in FIG. 8, the combined rear-side focal position of the first and second lenses is the first lens. 1.1 to the side
Just move. Therefore, in order to maintain a perfect telecentric optical system, it is necessary to move the third lens L _B3 1.1 forward, but the amount of movement is only about 1% compared with the focal length of the third lens L _B3. However, there is no problem even if the third lens L _B3 is fixed and is considered as a telecentric optical system in practice. In this case, if the object positions are the same, the change in image position is +0.22
The value is 6, which is almost the same as the amount of aberration of the lens, and can be ignored, although it depends on the brightness of the lens.

In this case, the combined focal length of the first and second lenses is
It becomes 111.1 and the imaging magnification becomes 0.9.

On the contrary, if the second lens L _B2 is moved 10 points forward (in the direction of the first lens L _B1 ) on the optical axis from the position shown by the solid line in FIG.
And the combined focal length of the second lens is 90.909, the multiplication factor is 1.1, and the movement of the second lens L _B2 10 before and after, 1.
22 magnification changes are possible. In the above description of the principle, the first, second, and third lenses are single lenses in order to simplify the illustration and description, but in reality, each of the first group lens and the second group is composed of a plurality of lenses. The lens is configured as a third lens group. For example, if the first lens group (each principal point: H ₁₁ , H ₁₂ ) and the third lens group (each principal point: H ₃₁ , H ₃₂ ) each have spherical aberration, the rays incident parallel to the optical axis Does not pass through the focal position, so that as shown in FIG. 9, the position where the spherical aberration amount ΔS (ΔS ₁ , ΔS ₂ ) is added to the focal position is made to coincide with the principal points H ₂₁ and H ₂₂ of the second lens group. There is a need. The value of the spherical aberration amount ΔS may be positive or negative depending on the configuration of the first and third lens groups.

That is, the relay lens L _B is configured as follows. It is composed of three lens groups having a positive focal length, and the rear focus position of the first lens unit L _{B1 and} the front focus position of the third lens unit L _B3 viewed from the object side are arranged so as to substantially match each other. Group lens L
The second group lens L _{B2 is provided} with an optical axis Z in the vicinity of the focal point of _B1 and L _B2.
It is arranged so that it can move along.

When the second lens group is moved, the combined focal position of the first lens group and the second lens group changes. Therefore, in order to maintain the characteristics of the telecentric optical system, the third lens group should be moved in accordance with the amount of change. It is necessary to make the front focus position coincide with the combined focus position of the first lens group and the second lens group. However, by appropriately selecting the focal lengths of the lenses of the third lens group, when the movement of the second lens group is small, the amount of variation in the combined focal position of the first lens group and the second lens group should be kept extremely small. Therefore, even if the third lens group is fixed, the telecentric optical system can be almost held.

Further, in order to change the multiplication factor greatly, it is necessary to increase the movement amount of the second lens group. In this case, the first
Since the variation of the combined focal point position of the group and the second group lens also becomes large, the third group lens is moved according to the variation amount, and the front side focal position thereof is set to the combined focal point position of the first group lens and the second group lens. Must match. With such a configuration, the telecentric imaging optical system is held, so that the imaging magnification that has been greatly changed does not change while being maintained even if the object distance is changed.

<< Effects of the Invention >> As is clear from the above description, the illumination optical system according to the present invention has the following effects.

I. Since the relay lens is configured to be able to perform zooming by zooming while maintaining the telecentric optical system on the entrance side and the exit side, the positions of the light source images formed in front of and behind the relay lens remain fixed. Good.

As a result, when changing the magnification of the microscope, it is possible to always maintain a perfect Keller illumination system that is telecentric with respect to the illuminated surface.

B. Further, since the position of the light source image does not move, when the aperture stop or the like is arranged there, the position may be always fixed, and the structure can be simplified and the cost can be reduced as compared with the movable type.

C. Further, in the case where the size of the entrance pupil of the objective lens changes depending on the magnifying power as in the epi-illumination system, by zooming the relay lens, the acceptance angle of the light flux emitted from the light source can be made smaller. Since the effective use area of can be set large, the amount of light substantially increases accordingly.

[Brief description of drawings]

1 to 3 relate to an illumination optical system according to the present invention.
FIG. 4 is a schematic diagram of an illumination optical system corresponding to the case where the magnification of the microscope is high, FIG. 2 is a case where the magnification is intermediate, and FIG. 3 is a diagram of the illumination optical system corresponding to the case where the magnification is low. Schematic diagrams showing the case of using the epi-illumination method, FIGS. 5 to 7
FIG. 8 is a schematic diagram for explaining the action of a relay lens in each of the above-mentioned epi-illumination optical systems, and FIG. 8 is a schematic diagram for explaining the principle of the relay lens of the present illumination optical system.
FIG. 8 is a principle diagram showing a case where spherical aberration is taken into consideration in FIG. 8, and FIGS. 10 to 12 are schematic diagrams corresponding to FIGS. 1 to 3 related to a conventional illumination optical system. S: Light source, L _A: collector lens, L _B: relay lens, L _C: condenser lens, L ₁
… Objective lens, P… Irradiated surface, P _A … Illuminated area of illuminated surface.

Claims (1)

[Claims] 1. A plurality of lenses forming a relay lens by arranging a collector lens, a relay lens, and a condenser lens in order from the light source side to form a telecentric Keller illumination system with respect to an irradiation surface of a microscope. In the illumination optical system of the microscope, which is configured to change the illumination area of the illuminated surface according to the magnification of the microscope, the collector lens is composed of a telecentric optical system on the output side and the relay is Illumination optical system for a microscope, characterized in that the lens is composed of an optical system that is telecentric on the incident side and the outgoing side and is capable of zooming.