JP2990859B2 - Variable illumination optical system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical system for an optical microscope.

[0002]

2. Description of the Related Art An illumination field of an illumination optical system (a range for illuminating a specimen surface) in an optical microscope changes depending on a magnification of an objective lens. Therefore, in order to illuminate more efficiently, the magnification of the illumination system (the size of the illumination field) depends on the magnification of the objective lens.
Needs to be changed. In a conventional illumination system, a method of preparing several types of condenser lenses having different focal lengths and exchanging them according to the magnification of the objective lens to change the illumination field has been general.

[0003]

In the prior art as described above, it is necessary to prepare a plurality of types of condenser lenses themselves, which increases the number of members of the microscope.
Also, in an optical microscope, it is necessary to satisfy general telecentric illumination conditions.Even if the focal length of the condenser lens changes, the front focal position of the condenser lens is set to the aperture stop of the illumination optical system or a position conjugate with it. Must be placed. For this reason, the arrangement of the other optical members constituting the illumination optical system must be changed in accordance with the replacement of the condenser lens, and there is a problem that the illumination system itself becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and provides a variable-magnification illumination that can easily change magnification without replacing a condenser lens and that maintains telecentric illumination conditions even after magnification change. It is an object to provide an optical system.

[0005]

According to the present invention, there is provided a Galileo variable power optical system which is configured to be insertable into and removable from the optical axis of an illumination optical system. When the focal length of the front group is F1, the focal length of the rear group is F2, and the distance between the principal points from the front group to the rear group is D, F1 + F2 = D. The Galileo variable power optical system is arranged so that, in the mounted state, the aperture stop position of the illumination optical system is sandwiched between the front group and the rear group of the Galileo variable power optical system. A variable magnification illumination optical system is provided.

In a preferred aspect of the present invention, when a distance on the optical axis between the aperture stop position of the illumination optical system and the principal point of the front group of the Galileo variable magnification optical system is d1, d1 = It is desirable that the configuration is such that F1 (F1 + F2) / (F1-F2). In a preferred aspect of the present invention, it is preferable that the front group and the rear group of the Galileo variable power optical system include a convex lens and a concave lens, or a concave lens and a convex lens, respectively. In a preferred aspect of the present invention, it is preferable that the Galileo variable power optical system is arranged from a sample surface in the order of a condenser lens of an illumination optical system and the Galileo variable power optical system.

[0007]

The present invention is configured as described above, and has the following effects. First, in the variable-magnification illumination optical system according to the present invention, the illumination system can be easily magnified by inserting and removing the Galileo variable-magnification optical system without replacing the condenser lens itself. Further, by arranging the relative positional relationship between the Galileo variable power optical system and the aperture stop position of the illumination optical system as described above, the condition of telecentric illumination of the illumination optical system can be maintained. In the present invention, the aperture stop position includes a position of the aperture stop on the optical axis of the illumination optical system and a conjugate position thereof.

Hereinafter, the operation of the present invention will be described in detail by taking a Galileo variable power system as shown in FIG. 1 as an example. In the following description, the sign is defined assuming that the traveling direction of light (the right direction in the figure) is positive. First, in order to maintain the telecentric illumination conditions in the illumination optical system, the condition is that there is no change in the position of the pupil even when the Galileo variable power system is inserted.

A Galileo variable power system as shown in FIG. 1 (shows a state inserted with the aperture stop H of the illumination system interposed).
, The focal length of the front group 1 across the pupil position H is f
_1, similarly when the focal length of the group 2 after sandwiching the pupil f _2, each principal point interval from the front group to the rear group 2 is D, the following condition Galileo variable power system (1) (2) Holds.

F ₁ + f ₂ = D (1) Expression β = f ₁ / f ₂ (2) Expression (β: Magnification of Galileo zoom system)

Next, as a condition that the position of the pupil does not change even after passing through the Galileo variable power system, consider the imaging of the principal ray in FIG. 1, when the distance from the front group 1 to the aperture stop (pupil) H and D _1, which is the object distance to the front group of the main ray. Similarly, the image point distance D ₁ by front unit 1 of the main beam ', the object distance is D ₂ to the group 2 after the principal ray, the image point distances by a group 2 after the main ray D _2' equal to or less than .

Here, from the lens formulas in the front group 1 and the rear group 2, the following equation (3) is established.

[0013]

(Equation 1)

Further, from D ₂ = D ₁ ′ −D, the following (4)
The formula holds.

[0015]

(Equation 2)

In order that the position of the pupil does not change, the object point of the principal ray incident on the Galileo variable power system must coincide with the image point after passing through the Galileo variable power. It is necessary to satisfy the following equation (5). D ₁ = D + D ₂ ′ (5)

From the above equations (1) to (5), the conditions for the pupil position of the illumination optical system not to change even when the Galileo variable power system is inserted will be analyzed. First, the expressions (3) and (4) are summarized as follows.

[0018]

(Equation 3)

[0019]

(Equation 4)

The following is a modification of the equation (1). f ₂ = D−f ₁ Expression (1a) From these, when Expressions (1a) and (3a) are substituted into Expression (4a) and rearranged, the following Expression (6) is obtained.

[0021]

(Equation 5)

Further, by transforming equation (5), D ₂ ′ = D ₁ −D (5a), and substituting equation (5a) into equation (6), the following equation (7) is obtained. .

[0023]

(Equation 6)

Here, by transforming equation (1), the following equation (1b) is obtained.
It becomes an expression. f ₁ −D = −f ₂ Equation (1b) When the equation (1b) is substituted into the equation (7), the equation (7a) is obtained.

[0025]

(Equation 7)

By transforming equation (2), the following equation (2a) is obtained.

[0027]

(Equation 8)

For this reason, when substituting equation (2a) into equation (7a),
Equation (7b) is obtained.

[0029]

(Equation 9)

From the equation (7b), the following equation (8) holds.

[0031]

(Equation 10)

Therefore, this equation (8) is a condition for keeping the pupil position unchanged even after passing through the Galileo variable power system. Here, in the Galileo variable power system, since the magnification β <0, β−1 <0
And the right side in the above equation (8) has the following relationship.

[0033]

[Equation 11]

Since | β | <| β−1 |, the following relationship is established.

[0035]

(Equation 12)

Therefore, from the above equation (8), the following equation (9) is established at an arbitrary magnification β of the Galileo variable power system.

[0037]

(Equation 13)

It can be seen from the equation (9) that 0 <D ₁ , D ₁ <D (10)

Therefore, when a Galileo variable power system having an arbitrary magnification is used from the condition of the above equation (10), the condition of the arrangement that the pupil of the illumination optical system does not change is that D ₁ is positive and D
Smaller it, that is, the position of the D ₁ must-have between f ₁ and f _2. Therefore, in order that the position of the pupil of the illumination optical system does not change even if the Galileo variable power system is inserted, it is necessary to arrange the Galileo variable power system with the aperture stop (pupil) interposed therebetween.

Here, from the above equation (8), when the conditions such as the front group, the rear group, and the interval of the Galileo variable power system are defined, the following equation (11) is a condition.

D ₁ = D · f ₁ / (f ₁ −f ₂ ) or = f ₁ (f ₁ + f ₂ ) / (f ₁ −f ₂ )
Equation (11)

Therefore, in the present invention, since the Galileo variable power system is inserted and removed so as to satisfy the above conditions, the illumination field can be easily adjusted without changing the condenser lens of the illumination optical system and maintaining the conditions of the telecentric illumination. An illumination system capable of zooming is realized.

[0043]

Embodiments of the present invention will be described below with reference to the drawings. 2, 3 and 4 show a part of an illumination optical system of an optical microscope according to one embodiment of the present invention.

In FIG. 2, the illumination optical system that illuminates the sample surface 40 performs illumination that satisfies the telecentric condition via the condenser lens 35. That is, the aperture stop 21 of the illumination optical system is formed at the front focal position of the condenser lens 35. In this state, the illuminated field 25 is only a limited portion as shown in the figure, and when observing at a high magnification with a microscope, illumination is performed with the Galileo variable power system removed.

Next, FIG. 3 shows a state in which the Galileo variable power system 30 is inserted on the optical axis of the illumination optical system. Here, the Galileo variable power system 30 includes a front convex lens 31 and a rear concave lens 32.
The aperture stop 21 is inserted between them. Assuming that the focal lengths of the front convex lens 31 and the rear concave lens 32 are f ₃₁ and f ₃₂ , respectively, the distance d ′ between the principal point position of the front convex lens 31 and the aperture stop 21 is given by the following equation (11). We are satisfied with expression.

D ′ = f ₃₁ (f ₃₁ + f ₃₂ ) / (f ₃₁ −f ₃₂ )

Accordingly, as described above in the section of the operation, even if the Galileo zooming system 30 is inserted, the pupil does not change.
Illumination that satisfies telecentric conditions is performed. In this case, the Galileo variable power system 30 controls the Teruo 27
However, even when the numerical aperture of the illumination light is reduced and a wide field of view is observed in low-magnification observation with a microscope, illumination that satisfies the telecentric condition is performed over the entire field of view. .

Further, as shown in FIG.
3 is composed of a front concave lens and a rear convex lens, and the Galileo variable power system 30 of FIG. 3 is inserted as an inverted configuration, so that the illumination field is narrower than that of FIG. Magnifying telecentric lighting conditions can be obtained. In this case as well, it goes without saying that the same relational expression as expression (11) holds.

[0049]

As described above, according to the present invention, since the pupil does not change even when the Galileo variable power system is inserted, it is easy to maintain the telecentric condition simply by inserting and removing the Galileo variable power system. Only Teruno can be zoomed.

Since these can be constructed only by configuring the Galileo variable power system so that it can be inserted into and removed from a predetermined position of the illumination optical system, there is an advantage that the fabrication is easy and the cost is low. More preferably, the condenser lens of the illumination optical system and the Galileo variable power optical system are arranged in this order from the sample surface. The zooming can be easily performed by inserting and removing the zoom lens on the side.

Further, since it is not necessary to prepare a plurality of condenser lenses and to maintain the telecentric condition at the time of conversion as in the conventional case, it is not necessary to change the arrangement of other optical members of the illumination optical system. It can be done easily.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an operation of the present invention.

FIG. 2 is a diagram illustrating a part of an illumination optical system of a microscope according to an embodiment of the present invention, and is an optical path diagram illustrating a telecentric illumination system without a Galileo variable power system.

FIG. 3 is a diagram illustrating a part of an illumination optical system of a microscope according to an embodiment of the present invention, and is an optical path diagram illustrating a telecentric illumination system in which a Galileo variable power system is inserted.

FIG. 4 is a diagram illustrating a part of an illumination optical system of a microscope according to an embodiment of the present invention, and is an optical path diagram illustrating a telecentric illumination system in which a Galileo variable power system is inverted and inserted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... front group of a Galileo variable power system, 2 ... rear group of a Galileo variable power system, H, 21 ... aperture stop, 25, 27 ... Teruno 30 ... Galileo variable power system, 31 ... Galileo variable power front convex lens 32 … Galileo zoom lens rear concave lens 35… Condenser lens 40… Sample surface

Claims (4)

(57) [Claims] 1. A zoom lens system comprising: a Galileo variable power optical system configured to be insertable into and removable from an optical axis of an illumination optical system, wherein the Galileo variable power optical system includes a front group and a rear group; The focal length is F1, the focal length of the rear group is F2,
When the distance between the principal points from the front group to the rear group is D, F1 + F2 = D, and the Galileo variable power optical system is such that the aperture stop position of the illumination optical system is A variable-magnification illumination optical system, which is arranged so as to be sandwiched between the front group and the rear group of the Galileo variable-magnification optical system. 2. When the distance on the optical axis between the aperture stop position of the illumination optical system and the principal point of the front group of the Galileo variable power optical system is d1, d1 = F1 (F1 + F2) / (F1) -F2), wherein:
The variable magnification illumination optical system according to 1. 3. The Galileo variable power optical system according to claim 1, wherein the front group and the rear group of the variable power optical system each include a convex lens and a concave lens, or a concave lens and a convex lens, respectively. Variable illumination optical system. 4. The Galileo variable power optical system according to claim 1, wherein a condenser lens of an illumination optical system and the Galileo variable power optical system are arranged in this order from a sample surface. A variable power illumination optical system according to claim 1.