JPH11174321A - Variable power device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an intermediate variable power mechanism free from the misalignment of optical axis at the time of varying power even when a rotary shaft has mechanical backlash. SOLUTION: A 1st objective lens 1 and a 2nd objective lens 2 are arranged on a main optical axis MA. A middle part between the lenses 1 and 2 forms a so-called infinite optical system. A 1st plane-parallel optical system 5 consisting of a pair of mirrors 5a and 5b is arranged on the lower side of the middle part, and a 2nd plane-parallel optical system 6 consisting of a pair of mirrors 6a and 6b is arranged on the upper side of the middle part. A sub optical axis SA in parallel with the main optical axis MA is formed by the optical system 5, and the optical path of a light beam from an object surface OS passing through the lens 1 is shifted to the sub optical axis SA side. Then, the optical path is restored to the main optical axis MA side from the sub optical axis SA side by the optical system 6. In the case of varying the power, the lenses 1 and 2 are integrally rotated around the main optical axis MA so as to properly change a variable power, optical system arranged on the sub optical axis SA.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming optical system for forming an image of a test object on an object plane on an image plane, and to perform a magnification change at an infinite optical system portion between the object plane and the image plane. It is about.

[0002]

2. Description of the Related Art FIG. 9 is a view showing an observation optical system provided with a conventional zooming device. This observation optical system is for imaging an object on the object plane OS on the image plane PS, and includes a plurality of intermediate variable optical systems 1 in an intermediate portion between the infinite optical systems 11 and 12.
It has a structure in which any one of 5a, 15b and 15c is arranged. These intermediate zoom optical systems 15a, 15b, 15
c can be replaced by the revolver mechanism 14. The revolver mechanism 14 holds the intermediate variable-magnification optical systems 15a, 15b, and 15c at positions around a rotary plate 14b having a central axis 14a at a position distant from the optical axis AX. When rotated, any one of the optical axes of the intermediate zoom optical systems 15a, 15b, and 15c matches the optical axis AX of the observation optical system.

[0003]

However, in the above-described zooming device, the intermediate zooming optical systems 15a, 15b, and 15c are caused by mechanical play of the central axis 14a of the revolver mechanism 14.
When the angle of the light incident on the light source changes, the angle of the emitted light also changes.

[0004] Assuming that the intermediate magnification of the intermediate variable power optical system arranged in the infinite optical system portion is m, the angular change of the outgoing light when the angular change of the incident light due to mechanical play is α is mα.
Therefore, when the incident light is used as a reference, the deflection angle of the output light due to the inclination α of the intermediate variable power optical system is (mα−α). That is, in the conventional magnification changing device, the image forming position is largely changed by the mechanical play of the revolver mechanism 14.
For this reason, when the observation optical system as shown in FIG. 9 is applied to an optical measuring instrument, there is a problem that the imaging position changes every time the magnification is changed, and a measurement error occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnification changing device which prevents a change in an imaging position when a magnification is changed.

[0006]

According to a first aspect of the present invention, there is provided a variable magnification apparatus, comprising: an image forming optical system for forming an object on an object surface onto an image surface; A variable power optical system having a variable power optical system in an infinite optical system portion provided between the variable power optical system and the variable power optical system disposed on the object plane side of the variable power optical system and incident along the main optical axis of the imaging optical system. A first optical element that emits the generated light in the same direction along a sub optical axis separated by a predetermined distance from the main optical axis, and is disposed on the image plane side of the variable power optical system, and And a second optical element for emitting light incident along the main optical axis in the same direction along the main optical axis. Thus, even if the first and second optical elements are slightly inclined with respect to the main optical axis, the sub optical axis is maintained parallel to the main optical axis. That is, since the incident angle of the incident light with respect to the variable power optical system is maintained, the adjustment of the variable power device becomes easy.

According to a second aspect of the present invention, the first and second optical elements can be turned synchronously around the main optical axis, and are caused by the turning of the first and second optical elements. A plurality of the variable power optical systems are arranged on a locus of the sub optical axis. Thus, when the first and second optical elements are rotated synchronously to move the sub optical axis to an arbitrary position of the variable power optical system at the time of the variable power, the optical axis of each variable power optical system can be changed. Even if the light is slightly inclined with respect to the optical axis, the angle of incidence and the angle of emergence of light to each variable power optical system can always be made to coincide with each other, so that the fluctuation of the image forming position on the image plane can be prevented.

The zooming device according to claim 3 is characterized in that the first and second optical elements are parallel plane optical systems each having a parallel plane. Thereby, even if the parallel plane optical system is tilted as a whole, the main optical axis and the sub optical axis can be maintained in parallel. The zooming device according to claim 4 is characterized in that the first and second optical elements are each a combination of a pair of corner cubes.
Thereby, even if the pair of corner cubes are integrally inclined, the parallelism between the main optical axis and the sub optical axis can be reliably maintained.

[0009] In a zooming device according to a fifth aspect, the first and second optical elements are each formed by combining a pair of cat's eyes. Thus, even if the pair of cat's eyes are integrally inclined, the parallel between the main optical axis and the sub optical axis can be reliably maintained.

The zooming device according to any one of claims 3 to 5 is particularly easy to adjust as described above. Even if the first and second optical elements are rotated as described in claim 2, there is no influence of the rotational play.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] An optical measuring machine incorporating a variable power device according to a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a view for explaining the overall structure of the optical measuring instrument. The optical measuring device shown in the drawing is an XY stage 2 on which a sample SP is placed and which is electrically moved two-dimensionally in a horizontal plane.
0, a head unit 30 for detecting an enlarged image or a reduced image of the sample SP on the XY stage 20, and an elevating mechanism 40 for elevating the head unit with respect to the XY stage 20. The head unit 30 includes an optical unit 31 for obtaining an image of the sample SP, a CCD camera 32 on which the image obtained by the optical unit 31 is projected, and laser projection and reception for detecting the height of the sample SP. And a height sensor 33 composed of a portion.

The image signal detected by the CCD camera 32 is
The image is taken into the control processing device 80, subjected to a predetermined process, and displayed on the display device 81 as an image of the sample SP. The control processing device 80 controls the operations of the XY stage 20 and the elevating mechanism 40 based on data and the like input from the input device 82. As a result, an enlarged image or the like of an arbitrary area on the sample SP can be obtained, and the coordinates of a point at which such an enlarged image has been obtained can be determined.

FIG. 2 is a diagram illustrating the optical unit 31 of FIG. 1 in more detail. The optical unit 31 includes the sample SP
An imaging optical system 71 for projecting the image on the imaging surface of the CCD camera 32 and an illumination optical system 72 for illuminating the sample SP. The imaging optical system 71 includes the first objective lens 1 on the sample SP side.
, A variable magnification device portion 3 having a movable portion, and a second objective lens 2 on the CCD camera 32 side. The variable magnification unit 3 holds a first and second parallel plane optical systems 5 and 6 and rotates around an optical axis AX (not shown).
And a variable power optical system 7a, 7b, 7c fixed to the main body side of the imaging optical system 71 and not rotating.

FIG. 3 is a diagram showing a detailed structure of the imaging optical system 71 of FIG. The first objective lens 1 and the second objective lens 2 are arranged on a first optical axis coinciding with the optical axis AX shown in FIG. This optical axis is hereinafter referred to as a main optical axis MA for convenience. Note that the illustrated object plane OS corresponds to the surface of the sample SP in FIG. 2, and the illustrated image plane PS corresponds to FIG.
Corresponds to the photoelectric detection surface of the CCD camera 32.

An intermediate portion between the first and second objective lenses 1 and 2 is a parallel optical system, forming a so-called infinite optical system. A first parallel plane optical system 5 including a pair of mirrors 5a and 5b is disposed below the intermediate portion (on the first objective lens 1 side), and above the intermediate portion (on the second objective lens 2 side). Also, a second parallel plane optical system 6 composed of a pair of mirrors 6a and 6b is arranged.

A pair of mirrors 5a, 5b constituting the first parallel plane optical system 5 are arranged at an angle of about 45.degree. With respect to the main optical axis MA, and are separated by a span S1 in the horizontal direction. A pair of mirrors 6 constituting the second parallel plane optical system 6
a and 6b are also arranged at an angle of about 45 ° with respect to the main optical axis MA and separated by a span S2 in the horizontal direction.
In addition, both spans S1 and S2 are substantially equal.
Each of the mirrors 5a, 5b, 6a, 6b is connected to the main optical axis MA.
Are arranged in the same plane. Here, the inclination angles of the pair of mirrors 5a and 5b may be other than 45 °. Note that, unlike the case of the above embodiment, the first and second
When a method of changing the arrangement of the sub optical axis SA by a mechanism in which the parallel plane optical systems 5, 6 rotate in directions opposite to each other with respect to an axis perpendicular to the main optical axis MA is adopted, a pair of mirrors 6a,
It is preferable that the tilt angle of 6b be a negative angle corresponding to the tilt angle of the pair of mirrors 5a and 5b, since the position of the output optical axis with respect to the incident optical axis does not change.

The first parallel plane optical system 5 allows the main optical axis M
A second optical axis parallel to A (this optical axis is
Is formed, and the optical path of the light beam from the object plane OS passing through the first objective lens 1 is shifted from the main optical axis MA to the sub optical axis SA. Further, the optical path is returned from the sub optical axis SA to the main optical axis MA by the second parallel plane optical system 6.

In order for the optical path returning from the sub optical axis SA to the main optical axis MA to exactly coincide with the original main optical axis MA, the span S1 which is the horizontal distance between the pair of mirrors 5a and 5b is required. A span S2 which is a horizontal distance between the pair of mirrors 6a and 6b.
Is ideal, but in this embodiment, since an infinite optical system is assumed, a slight difference in span can be ignored.

The first and second plane-parallel optical systems 5 and 6 are rotatable around the main optical axis MA while maintaining their positional relationship by a rotation mechanism (not shown). That is,
The pair of mirrors 5a and 5b can rotate integrally about the main optical axis MA while keeping the span S1 constant, and the pair of mirrors 6a and 6b are also connected to the pair of mirrors 5a and 5b. Synchronously, it is possible to turn around the main optical axis MA integrally while keeping the span S2 constant. Thereby, the auxiliary optical axis SA is separated from the main optical axis MA by the span S1 = S2.
Can be appropriately rotated and moved.

A circumference (cylindrical orbit) around which the sub optical axis SA rotates.
Above, a plurality of variable power optical systems 7a, 7b, 7c are fixedly arranged. When the first and second parallel plane optical systems 5 and 6 are integrally rotated to make the optical axis of any of the variable magnification optical systems 7a, 7b and 7c coincide with the sub optical axis SA, the image is formed on the image plane PS. The enlargement ratio or reduction ratio of the image to be formed can be changed by three magnification stages.

Incidentally, if the case where nothing is arranged in the intermediate portion is included, the intermediate zoom having the number of zooming stages equal to the number of zooming optical systems arranged on the circumference around which the sub optical axis SA rotates +1 is included. A double mechanism can be realized. In the case of increasing the number of zooming stages, by increasing the spans S1 and S2 to increase the radius of rotation, it is possible to easily arrange a plurality of zooming optical systems.

Hereinafter, the influence of the attitude of the variable power optical systems 7a, 7b, 7c on the sub optical axis SA will be considered. As described above, since the intermediate portion between the first and second objective lenses 1 and 2 is a so-called infinite optical system, the variable magnification optical systems 7a and 7
The three translational components b and 7c (parallel movement in the direction of the main optical axis MA and parallel translation in two orthogonal directions in a plane orthogonal to the main optical axis MA) and one rotation component around the sub optical axis SA are as follows. Image plane P
It does not affect the imaging state on S. The two rotation components in the direction orthogonal to the sub optical axis SA affect the image formation state as a lateral shift of the image on the image plane PS. However, since each of the variable magnification optical systems 7a, 7b, 7c is individually fixedly arranged, the amount of the above two rotation components orthogonal to the sub optical axis SA is always kept constant, and the image on the image plane PS is kept. Is constant and does not fluctuate. As described above, the lateral shift amount is a fixed amount for each magnification corresponding to each of the variable magnification optical systems 7a, 7b, and 7c. It is also possible to make correction.

Hereinafter, the first and second parallel plane optical systems 5 and 6 will be described.
The influence of the posture on the auxiliary optical axis SA will be considered. Each of the first and second parallel plane optical systems 5 and 6 maintains the parallel between the incident optical axis and the outgoing optical axis even if it is slightly changed in attitude (three translational components and three rotational components). There is a property that.

FIG. 4 is a diagram for explaining the effect of the inclination of the first parallel plane optical system 5. As shown in FIG. FIG. 4A shows a pair of mirrors 5.
FIGS. 4A and 4B show the case where the postures of FIGS.
FIG. 4B shows a case where the pair of mirrors 5a and 5b rotate counterclockwise around an axis perpendicular to a plane including the main optical axis MA and the sub optical axis SA. FIG. Mirror 5a, 5
The case where b rotates clockwise around an axis perpendicular to a plane including the main optical axis MA and the sub optical axis SA is shown.

In the case of FIG. 4A, the first parallel plane optical system 5
Is maintained, the distance between the main optical axis MA and the sub optical axis SA is a predetermined span S1, and the parallel between the main optical axis MA and the sub optical axis SA is also maintained. In the case of FIG.
The parallel plane optical system 5 rotates counterclockwise, and the main optical axis MA
The distance between the sub optical axis SA and the sub optical axis SA is larger than a predetermined span S1, but the parallel between the main optical axis MA and the sub optical axis SA is maintained. In the case of FIG. 4C, the first parallel plane optical system 5 rotates clockwise, and the distance between the main optical axis MA and the sub optical axis SA is smaller than the predetermined span S1. Axis MA
And the sub-optical axis SA are kept parallel.

As is apparent from the above description, even if the rotation mechanism for holding and rotating the first parallel plane optical system 5 has a backlash or the like, the parallel relationship between the main optical axis MA and the sub optical axis SA is out of order. There is no. In the second parallel plane optical system 6, the incident optical axis and the outgoing optical axis are kept parallel in the same manner as described above. Therefore, if the spans S1 and S2 of the first and second parallel plane optical systems 5 and 6 are set to be substantially equal, the parallel relationship between the main optical axis MA and the sub optical axis SA is maintained, and the distance from the sub optical axis SA increases. Main optical axis M
The parallel relationship with the original main optical axis MA is maintained for the optical path returning to A. In this way, in the two parallel plane optical systems 5 and 6 which are movable parts, the influence of the two rotation components in the direction orthogonal to the main optical axis MA or the sub optical axis SA does not occur, and the first and second objectives are not affected. Since the intermediate portion between the lenses 1 and 2 is a so-called infinite optical system, as a result, it is possible to realize an intermediate zoom mechanism without optical axis shift.

[Second Embodiment] Hereinafter, a variable power apparatus according to a second embodiment of the present invention will be described. The zooming device of the second embodiment is obtained by modifying the first and second parallel plane optical systems 5 and 6 constituting the zooming device portion 3 of the first embodiment.

FIG. 5 is a view for explaining the main parts of a variable magnification device according to the second embodiment. The first parallel plane optical system 105 is similar to the one shown in FIG.
Pair of mirrors 10 corresponding to the pair of mirrors 5a, 5b
5a, 105b, and both mirrors 105a, 105b.
A sub-parallel plane optical system composed of a pair of mirrors 105c and 105d is arranged between 5b. Thereby, the main optical axis M
Light incident on the first parallel plane optical system 105 along A can be emitted in the same direction along the sub optical axis SA separated from the main optical axis MA by a predetermined distance. On the other hand, the second parallel plane optical system 106 includes a pair of mirrors 106a and 106b corresponding to the pair of mirrors 6a and 6b in FIG. 3, and further includes a pair of mirrors 106 between the two mirrors 106a and 106b.
A sub-parallel plane optical system composed of c and 106d is arranged. Thereby, the light incident on the second parallel plane optical system 106 along the sub optical axis SA can be returned to the main optical axis MA and emitted in the same direction. At the time of zooming, the zoom optical system arranged on the sub optical axis SA is appropriately replaced, as in the case of the first embodiment.

[Third Embodiment] Hereinafter, a magnification changing apparatus according to a third embodiment of the present invention will be described. The zooming device of the third embodiment is obtained by further modifying the first and second parallel plane optical systems 105 and 106 of the second embodiment.

FIG. 6 is a view for explaining the main parts of a variable magnification device according to the third embodiment. The first parallel plane optical system 205 includes a pair of mirrors 205 between a pair of mirrors 105a and 105b.
A sub-parallel plane optical system composed of c and 205d is arranged. The two mirrors 205c and 205d are arranged by changing the inclination and the interval of the pair of mirrors 105c and 105d shown in FIG. 5, and have a function of parallelly moving the incident light and emitting it. On the other hand, the second parallel plane optical system 206 also includes a pair of mirrors 20 between the pair of mirrors 106a and 106b.
A parallel plane optical system composed of 6c and 206d is arranged. Both mirrors 206c and 206d are also arranged by changing the inclination and the interval of the pair of mirrors 106c and 106d shown in FIG. 5, and have the function of translating the incident light to emit it.

With the above optical arrangement, even if the first and second parallel plane optical systems 205 and 206 are integrally inclined, the light incident along the main optical axis MA is parallelized by a predetermined distance from the main optical axis MA. Can be emitted along the sub optical axis SA which is separated from the main optical axis MA, and the light traveling along the sub optical axis SA can be returned to the main optical axis MA again and emitted.

[Fourth Embodiment] Hereinafter, a magnification changing apparatus according to a fourth embodiment of the present invention will be described. The zooming device of the fourth embodiment is obtained by modifying the first and second parallel plane optical systems 105 and 106 of the second embodiment.

FIG. 7 is a view for explaining the main parts of a variable power device according to a fourth embodiment. The first parallel plane optical system 305 includes a pair of opposed corner cubes 305a and 305b. The light that has entered the first parallel plane optical system 305 along the main optical axis MA exits in the same direction along the sub optical axis SA that is separated from the main optical axis MA by a predetermined distance. The second parallel plane optical system 306 also includes a pair of opposing corner cubes 306a, 3
06b. Light incident on the second parallel plane optical system 306 along the sub optical axis SA returns to the main optical axis MA and exits in the same direction.

With the above optical arrangement, even if the first and second plane-parallel optical systems 305 and 306 are integrally tilted, the light incident along the main optical axis MA is emitted along the sub-optical axis SA. The light traveling along the sub optical axis SA can be returned to the main optical axis MA again and emitted.

[Fifth Embodiment] Hereinafter, a variable power apparatus according to a fifth embodiment of the present invention will be described. The zooming device of the fifth embodiment is obtained by modifying the first and second parallel plane optical systems 305 and 306 of the fourth embodiment.

FIG. 8 is a view for explaining the main parts of a variable-magnification apparatus according to the fourth embodiment. The first parallel plane optical system 405 includes a pair of opposed cat's eyes 405a and 405b.
The second parallel plane optical system 406 also includes a pair of opposed cat's eyes 406a and 406b. As is well known, each of the cat's eyes 405a, 405b, 406a, and 406b has a structure in which a lens and a reflecting mirror are combined to generate outgoing light parallel to incident light. Main optical axis M
Light incident on the first parallel plane optical system 405 along A exits in the same direction along the sub optical axis SA. Light incident on the second parallel plane optical system 406 along the sub optical axis SA is returned to the main optical axis MA and exits in the same direction.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment. For example, a rhombic prism (parallelogram prism) can be used instead of the parallel plane mirrors constituting the first and second parallel plane optical systems 5 and 6 shown in FIG.

Further, the intermediate portion between the first and second objective lenses 1 and 2 does not need to be an infinite optical system in a strict sense. As in the case of (1), the fluctuation of the imaging position can be reduced.

Unlike the above embodiment, FIG.
The first and second parallel plane optical systems 5 and 6
Are rotated in directions opposite to each other with respect to an appropriate horizontal axis orthogonal to the main optical axis MA by the main optical axis MA of the sub optical axis SA.
And the variable power optical system can be arranged at any position on the locus of the sub optical axis SA. in this case,
The inclination angle of the pair of mirrors 6a and 6b is
A negative angle corresponding to the inclination angles a and 5b is preferable because the position of the output optical axis with respect to the incident optical axis does not change.

[0041]

As is apparent from the above description, according to the zooming device of the first aspect, even if the first and second optical elements are slightly inclined with respect to the main optical axis, the sub optical axis is maintained at the main optical axis. Maintained parallel to the optical axis. Thus, even if the first and second optical elements are slightly inclined with respect to the main optical axis, the sub optical axis is maintained parallel to the main optical axis. That is, since the incident angle of the incident light with respect to the variable power optical system is maintained, the adjustment of the variable power device becomes easy.

According to the zooming device of the second aspect, at the time of zooming, the first and second optical elements are turned synchronously to move the sub optical axis to an arbitrary position of the zooming optical system. Thus, even if the optical axis of each variable power optical system is slightly inclined with respect to the sub optical axis, the angle of incidence and the output angle of light to each variable power optical system can always be made to coincide with each other. Variations in the image position can be prevented.

According to the third, fourth and fifth aspect of the present invention, even if the parallel plane optical system, the pair of corner cubes, and the pair of cat's eyes are tilted as a whole, the main optical axis and the auxiliary Parallelism with the optical axis can be reliably maintained.

The zooming devices of claims 3 to 5 are particularly easy to adjust as described above, and are not affected by the rotation play even if the first and second optical elements are rotated as in claim 2.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the overall structure of an optical measuring instrument incorporating a variable power device according to a first embodiment.

FIG. 2 is a diagram illustrating an optical unit of the optical measuring device of FIG.

FIG. 3 is a diagram illustrating a variable magnification device incorporated in the optical unit of FIG. 2;

FIG. 4 is a diagram illustrating the operation of a parallel plane optical system.

FIG. 5 is a diagram illustrating the structure of a variable power device according to a second embodiment.

FIG. 6 is a diagram illustrating the structure of a variable power device according to a third embodiment.

FIG. 7 is a diagram illustrating the structure of a variable power device according to a fourth embodiment.

FIG. 8 is a diagram illustrating the structure of a variable power device according to a fifth embodiment.

FIG. 9 is a diagram illustrating a conventional variable power device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st objective lens 2 2nd objective lens 3 Magnification device part 5, 6 1st and 2nd parallel plane optical system 5a, 5b, 6a, 6b Mirror 7a, 7b, 7c Magnification optical system 31 Optical unit 32 CCD camera 71 Imaging optical system 72 Illumination optical system MA Main optical axis SA Secondary optical axis

Claims (5)

[Claims] 1. An image forming optical system for forming an image of an object on an object surface on an image surface, wherein the variable magnification optical system is provided at an infinite optical system portion provided between the object surface and the image surface. At the same time, the light incident along the main optical axis of the imaging optical system is arranged along the sub optical axis separated from the main optical axis by a predetermined distance while being disposed on the object plane side of the variable power optical system. A first optical element that emits light in a direction, and a second optical element that is arranged on the image plane side of the variable power optical system and emits light incident along the sub optical axis in the same direction along the main optical axis. A variable power device comprising: an optical element. 2. The optical system according to claim 1, wherein the first and second optical elements are rotatable in synchronization about the main optical axis, and a plurality of optical elements are provided on a trajectory of the sub optical axis generated by the rotation of the first and second optical elements. The variable power apparatus according to claim 1, wherein the variable power optical system is arranged. 3. The variable power apparatus according to claim 1, wherein the first and second optical elements are parallel plane optical systems each having a parallel plane. 4. The variable power apparatus according to claim 1, wherein the first and second optical elements are each a combination of a pair of corner cubes. 5. The variable power apparatus according to claim 1, wherein the first and second optical elements are each a combination of a pair of cat's eyes.