KR101593870B1 - Telecentric optics device - Google Patents

Abstract

The present invention relates to a focal distance-variable telecentric optics device which may vary a focal distance. More specifically, the focal distance-variable telecentric optics device comprises: a body having both open ends; a fixed lens portion installed in the body to be fixated; a movable lens portion installed in the body and movable in a longitudinal direction of the body; and a lens driving portion installed in a portion of the body, moving the movable lens portion. The focal distance-variable telecentric optics device may prevent a quality of a capture image of an object to be inspected from deteriorating by moving the movable lens portion through the lens driving portion when the object to be inspected deviates from depth of field during imaging of the object to be inspected, and may allow all principal rays to be parallel to a central axes of the fixed lens portion and the movable lens portion in an image space or an object space even when a focal distance to the object to be inspected is changed. Accordingly, even when the object to be inspected deviates from depth of field, or a focal distance thereto is changed; all the principal rays may remain parallel to the optical axis in the image space or the object space, and the quality of the capture image of the object to be inspected may be prevented from deteriorating.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a telecentric optical device,

The present invention relates to a telecentric optical device for variable focal lengths which can vary the focus.

First, a telecentric system will be briefly described.

The telecentric system refers to an optical system in which the entrance pupil and the exit pupil are at an infinite distance. This is realized by placing the aperture stop in an image space, a water space focal plane or a position conjugate to it. All main rays travel in parallel to the axis as they are in the water space or above. Therefore, even when there is an error in the setting of the object surface or the selection of the upper surface, there is an advantage that the error of the size of the image taken or measured can be reduced. Therefore, it is used in an optical system such as a profile projector or an object size measuring machine.

Such a telecentric lens has a problem that the image is not clear when the focal length between the object and the lens changes.

In the conventional telecentric lens, the focus area is fixed, and thus the above problem occurs when the distance between the object and the lens is changed.

To solve this problem, a moving means for moving the telecentric lens in its entirety has been developed.

That is, in order to photograph a wide plane object, the telecentric lens is moved while moving in a direction perpendicular to the optical axis. If the thickness of the object changes, the focal distance changes. Therefore, the entire telecentric lens must be moved along the optical axis have.

Accordingly, since the moving means has to move the telecentric lens back and forth, up and down, right and left, there is also a problem that an error occurs due to abrasion and deflection of the moving means.

In addition, because of the nature of the telecentric lens, it is necessary to move it very precisely, and there is also a problem that a high cost is incurred for manufacturing the moving means.

Korean Patent Publication No. 10-2008-0033230 (Apr. 16, 2008)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art described above, and it is an object of the present invention to provide an image pickup apparatus and an image pickup apparatus capable of maintaining a state in which all principal rays are parallel to an optical axis in an upper space or a water space, Which is capable of preventing a decrease in the focal length of the telecentric optical system.

Further, there is provided a telecentric optical device for variable focal length, which can illuminate the object to be inspected clearly by providing illumination parallel to the optical axis, and can focus the entire optical device without moving the optical device on the optical axis when the focal length is changed It has its purpose.

In order to achieve the above object,

A movable lens unit which is installed inside the main body and is movable in the longitudinal direction of the main body, and a movable lens unit which is installed in a part of the main body, And a lens driving unit for moving the lens unit. When the subject is out of the depth of field at the time of photographing the object to be inspected, the moving lens unit is moved through the lens driving unit to prevent the captured image of the object to be inspected from being degraded. The light rays) are kept parallel to the central axis of the fixed lens and the movable lens part in the image space or water space.

In addition, when the lens driving unit rotates, the driving lens unit can move in the longitudinal direction of the main body.

The apparatus may further include a lighting unit installed in a part of the main body and irradiating the inspection object with light.

The imaging apparatus may further include a photographing unit disposed in the vicinity of the moving lens unit and installed in the main body, wherein the photographing unit can obtain photographing image information of the inspection object through the fixed lens unit and the moving lens unit.

In addition,

Wherein when the light is irradiated from the coaxial illumination to the refracting portion, light is made parallel by the refracting portion to the central axis, and the fixed lens portion is transmitted through the refracting portion And can be irradiated onto the inspection object.

Further, the distance between the fixed lens section and the photographing section is constant, and the movable lens section can move between the fixed lens section and the photographing section.

According to the present invention, it is possible to maintain the lateral magnification and the telecentric angle on the object to be inspected when the focal length is changed.

In addition, even if the depth of focus is shifted, the moving lens portion can be moved to adjust the depth of field, thereby improving the high resolution.

In addition, it is possible to minimize longitudinal spherical aberration, astigmatism, surface curvature, and distortion aberration.

In addition, the distance between the object and the photographing unit can be kept constant, and an accurate photographing image can be obtained.

Further, if the thickness of the object is changed, the focus can be achieved without moving the present invention on the optical axis.

Further, by providing illumination parallel to the optical axis, a sufficient amount of light can be ensured, focus acquisition and photographing speed can be improved, and furthermore, the shadow of an object can be minimized, so that a more precise photographing image can be obtained.

1 is a perspective view of a telecentric optical device for variable focal length according to an embodiment of the present invention;
2 and 3 are perspective and side cross-sectional views of a focal length variable telecentric optical device according to an embodiment of the present invention.
Figs. 4 and 5 are front sectional views schematically showing a use state of a telecentric optical device for variable focal length according to an embodiment of the present invention; Fig.
6 is a diagram schematically illustrating the driving state of a lens in a telecentric optical device for variable focal length according to an embodiment of the present invention;
FIGS. 7 to 9 are graphs showing results of using the telecentric optical system for variable focal length according to an embodiment of the present invention. FIG.

The preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings, in which the technical parts already known will be omitted or compressed for the sake of brevity.

1 to 5, a telecentric optical system for variable focal length according to an embodiment of the present invention includes a main body 1, a fixed lens unit 2, a movable lens unit 3, (4). Here, the illumination unit 5 and the photographing unit 6 are further included.

The main body 1 has a basic outer shape and includes a first body 11, a second body 12, a third body 13, a detachable piece 14 and a coupling portion 15.

The first body 11 is a cylindrical body in which the stationary lens unit 2 is housed, and has a substantially cylindrical shape with both ends open. The outer diameter and the inner diameter of the first body 11 are small.

The second body 12 is formed in a cylindrical shape having both ends thereof opened and accommodating the refraction portion 52 therein. The inner diameter of the second body 12 is formed such that the upper and lower portions are large and the diameter of the middle portion is small. The through hole 121 is formed in the second body 12 so as to allow light to flow from the coaxial illumination 51 to be described later and is screwed to the upper end of the first body 11.

The third body 13 is formed in a cylindrical shape in which the moving lens section 3 is accommodated therein and is substantially open at both ends. The outer diameter and the inner diameter of the third body 13 are occupied, and the inner diameter is enlarged toward the upper part. The upper end is formed smaller and smaller again.

The third body 13 is formed with a pair of guide grooves 131 through which the guide screws 41 are fitted on the outer surface of the third body 13 in a substantially slotted manner and is screwed to the upper end of the second body 12. A description thereof will be described later.

The detachable piece 14 has a substantially cylindrical shape and is formed with a stepped outer diameter and an inner diameter. A threaded hole SH is formed around the lower portion to hold a fixing bolt (not shown) Threaded.

That is, after the detachable piece 14 and the third body 13 are screwed into each other, in order to prevent the detachable piece 14 from being disengaged from the third body 13, Tighten and tighten the fixing bolts.

As a result, it is possible to prevent the detachable piece 14 from being released from the third body 13.

The engaging portion 15 is formed in a cylindrical shape having both ends open and has a stepped outer diameter and an inner diameter. A screw hole SH is formed around the engaging portion 15 to hold a fixing bolt (not shown) And the lower end thereof is fitted to the upper end of the detachable piece 14. As shown in Fig.

That is, when the engaging portion 15 and the releasing piece 14 are engaged with each other, the fastening bolt is inserted into the screw hole SH of the engaging portion 15 so that the engaging portion 15 and the releasing piece 14 are fastened together .

Accordingly, the engaging portion 15 and the releasing piece 14 can be easily engaged or separated by loosening or tightening the fixing bolts screwed into the engaging portion 15.

The fixed lens unit 2 is provided inside the first body 11 and includes a first fixed lens 21, a second fixed lens 23 and a third fixed lens 23 having different sizes and shapes, .

The fixed lens section 2 has a first fixed lens 1 having the largest outer diameter disposed on the lower portion of the first body 11, a second fixed lens 2 having a medium-sized outer diameter and a convex lens and a concave lens, A third fixed lens 23 having a small outer diameter and a convex lens and a concave lens superimposed thereon is disposed on the upper portion of the first body 11. The first fixed lens 23 is disposed at the center of the first body 11,

At this time, a substantially cylindrical spacer S is inserted between the first fixed lens 21 and the second fixed lens 23 and between the second fixed lens 23 and the third fixed lens 23, A lens fixing ring LR is fitted to the lower portion of the lens 21 and screwed to the lower portion of the first body 11. Thus, the first fixed lens 21, the second fixed lens 23 and the third fixed lens 23 are arranged at regular intervals by the spacer S, and the first fixed lens 21, the second fixed lens 23, The lens 21, the second fixed lens 23, and the third fixed lens 23 are firmly fixed to the first body 11.

The moving lens section 3 moves upward and downward within the third body 13 and includes a lifting section 31, a seating section 32 and two moving lenses 33.

A pair of screw holes 311 are formed around the lower portion of the elevating portion 31 so that the guide screw 41 is fitted in the lower portion of the elevating portion 31, 3 body (13). That is, the screw holes 311 and the guide grooves 131 of the third body 13 are aligned with each other while the elevating part 31 is inserted, and then the guides 33 of the third body 13 And is screwed into the screw hole 311 of the elevating portion 31 through the groove 131. The elevating part 31 is restrained by the guide screw 41 to the third body 13 and the guide screw 41 is guided by the guide groove 131 and the elevating part 31 is moved to the third body 13 Up or down.

The seat portion 32 has a substantially cylindrical shape with both ends open, an inner diameter of which is gradually increased toward the upper portion, a lower portion of the inner diameter is formed in a truncated triangular shape, and an outer diameter of the seat portion 32 is increased. In addition, a pair of adjustment grooves 321 are formed on the upper surface of the seat portion 32, and inserted into the upper portion of the lift portion 31 to be screwed. At this time, a well-known tool is inserted into the adjusting groove 321 to adjust the height of the mounting part 32, and the mounting part 32 is rotated. Accordingly, the height of the seat portion 32 can be adjusted by rotating the seat portion 32 using a known tool, and the seat portion 32 moves together with the lift portion 31. [

The moving lens 33 overlaps the convex lens having the same outer diameter and the concave lens and is fitted to the upper portion of the seating portion 32. [ At this time, the lens fixing ring LR is screwed to the upper part of the mounting part 32 to fix the moving lens 33 to the mounting part 32 while the moving lens 33 is fitted in the mounting part 32. [ Accordingly, the moving lens 33 moves together with the seat portion 32, and the moving lens 33 can adjust the focal length and depth by moving.

The lens driving unit 4 includes a guide screw 41 and an adjusting knob 42 for raising or lowering the elevating unit 31.

A pair of guide screws 41 are provided and the head is inserted into the guide groove 131 and a part of the head is projected to the outside and the screw part is screwed into the screw hole 311 of the elevating part 31. That is, the screw hole 311 is aligned with the guide groove 131 of the third body 13 in the state where the elevation part 31 is inserted, and then the guide groove 41 of the third body 13 131 and screwed into the screw hole 311 of the elevating portion 31. [

The adjustment knob 42 has a cylindrical shape with an approximately open end at both ends and has a threaded portion corresponding to the head of the guide screw 41. The outer surface of the adjustment knob 42 is formed with concavities and convexities 13 and rotates.

Further, the adjustment knob 42 is formed with a threaded hole SH through which a fixing bolt (not shown) is coupled around the inside thereof. The adjusting knob 42 can be fixed to the third body 13 by fastening the fixing bolt coupled to the circumference of the adjusting knob 42 and the moving lens portion 3 can be fixed by fixing the adjusting knob 42. [ Is fixed.

In order to assemble the adjusting knob 42, the adjusting knob 42 is inserted into the third body 13 while the elevating part 31 and the guide screw 41 are engaged with the third body 13, Is inserted into the third body 13 while being rotated.

When the adjustment knob 42 is rotated, the head of the guide screw 41 is fitted into the threaded hole of the adjustment knob 42, and the adjustment knob is mounted on the third body 13 while rising along with the guide screw 41 Loses.

At this time, the ring-shaped restraining ring 43 is screwed to the lower portion of the third body 13 in a state where the adjustment knob 42 is completely fitted around the third body 13.

The adjusting knob 42 is restrained by the restricting ring 43 to the third body 13 and the elevating portion 31 is moved up and down by rotating the adjusting knob 42. [

The illuminating unit 5 includes a coaxial illuminator 51 and a refracting unit 52 for irradiating light to an object to be inspected (not shown) in order to secure a light amount.

The coaxial illumination light 51 is inserted into the through hole 121 of the second body 12 and is screwed into the second body 12 using the well-known illumination. At this time, the coaxial illumination light 51 is arranged at a right angle to the central axis of the second body 12. A description thereof will be described later.

The refracting section 52 refracts light from the coaxial illumination 51 and is provided inside the second body 12 with two prisms or the like. Here, the refracting portion 52 is provided so that the inclined surface of the prism forms an angle of 45 DEG from the bottom surface, and the inclined surfaces of the two prisms face each other.

When the refracting portion 52 is disposed on the second body 12, a ring-shaped prism retaining ring PR is screwed on the upper and lower portions of the second body 12, And is coupled to the second body 12 so as to be in close contact with the upper surface and the lower surface of the first portion 52. Accordingly, the refraction portion 52 is firmly fixed to the second body 12, and the center of the light emitted from the coaxial illumination 51 is adjusted by moving the refraction portion 52 through the prism fixing ring PR . When the coaxial illumination 51 is operated, the light of the coaxial illumination 51 is emitted to the inclined surface of the refraction portion 52, and the light striking the inclined surface is reflected and emitted through the first fixed lens 21.

The photographing section 6 is coupled to the upper end of the engaging section 15 by converting the photographed image into digital image data by using the known image capturing device.

Thus, the photographed image is received through the fixed lens unit 2 and the movable lens unit 3, and the received image is converted into digital image data and is generated.

Although the lens driving unit 4 described above is described as being operated manually, it may be automatically operated using a known technique. That is, the lens driving unit 4 and the photographing unit 6 are interlocked to automatically operate the lens driving unit 4, thereby automatically adjusting the focus. A well-known technique such as a digital camera or the like is used for the explanation, and a detailed description will be omitted.

In addition, according to the present invention, at least one of the number of lenses, the diameter of the lenses, and the distance of the moving lens unit 3 may vary depending on the working distance and magnification.

Hereinafter, a use state of the telecentric optical device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

The light emitted from the illuminating unit 5 passes through the refracting unit 52 and the stationary lens unit 2 to the inspection object (not shown) by operating the illuminating unit 5 after arranging the present invention at a predetermined distance from the inspection object And is projected.

The light projected onto the inspection object is again transmitted to the photographing section 6 via the fixed lens section 2, the refraction section 52 and the moving lens section 3.

At this time, the photographing unit 6 photographs the object to be inspected and determines whether the object of the object to be inspected is properly focused through the photographing unit 6. [

Here, when the image is blurred due to out of focus, the adjustment knob 42 is rotated to focus.

Even if the next object to be inspected is different in height from the previous object to be inspected, the focus of the object to be inspected can be precisely adjusted by moving the movable lens unit 3 through the adjustment knob 42, thereby obtaining an image with a clear image quality.

In order to support this, the use result value of the telecentric optical device according to the embodiment of the present invention in which the NA (numerical aperture) is 0.045, the magnification is 2.5 times, and the moving distance of the moving lens part 3 is set to 3.4 mm 6 to FIG.

Figs. 7 to 9 show the positions of the moving lens 33 according to the working distance, and Figs. 7 to 9 show the positions of the moving lens 33 and the optical system field, respectively, in which the working distance is 137 mm, 140 mm, It is a field curves graph.

6 to 9, it can be seen that the telecentric angle is within 0.05 deg. Within the error range and the distortion rate is within 0.05% within the working distance of 137 mm to 143 mm.

Therefore, even if the thickness of the object to be inspected is different, it is not necessary to move the entirety of the present invention. Because the moving lens section 3 is moved and taken, Precise shooting is possible within.

In describing the present invention described above, the same reference numerals are used for the same configurations even if the embodiments are different, and the description thereof may be omitted if necessary.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Shall not be construed as being understood. Therefore, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. The present invention is not limited thereto.

One; main body
11; The first body
12; The second body
121; Through-hole
13; Third body
131; Guide groove
14; Detachment piece
15; Engaging portion
2; The fixed-
21; The first fixed lens
22; The second fixed lens
23; The third fixed lens
3; The moving lens section
31; Elevating portion
311; Screw hole
32; Seat portion
321; Adjusting groove
33; Moving lens
4; The lens-
41; Guide Screw
42; Adjustment knob
43; Constraining ring
5; Illumination unit
51; Coaxial lighting
52; Refraction part
6; Shooting section
LR; Lens retaining ring
PR; Prism retaining ring
S; Spacer
SH; Screw hole

Claims (6)

A body having both ends opened;
A fixed lens unit installed inside and fixed to the main body;
A moving lens unit installed inside the main body and movable in the longitudinal direction of the main body;
A lens driving unit installed on a part of the main body and moving the moving lens unit; And
And a lighting unit installed in a part of the main body and irradiating light to the inspection object,
The illumination unit includes:
A refracting portion for refracting light and a coaxial light for irradiating light to the refracting portion,
When the light is irradiated to the refracting portion in the coaxial illumination, light is irradiated to the inspection object by passing through the fixed lens portion and parallel to the center axis of the fixed lens portion by the refracting portion, It is possible to prevent the photographed image of the object to be inspected from being deteriorated by moving the movable lens unit through the lens driving unit and to prevent all the principal rays from being incident on the fixed lens And a focal length variable telecentric optical device for maintaining a state parallel to the central axis of the movable lens section.
The method according to claim 1,
Wherein when the lens driving unit rotates, the moving lens unit moves in the longitudinal direction of the main body.
delete The method according to claim 1,
And a photographing unit disposed in the vicinity of the moving lens unit and installed in the main body,
Wherein the photographing unit acquires image information of the object to be inspected through the fixed lens unit and the movable lens unit.
delete 5. The method of claim 4,
Wherein the distance between the fixed lens section and the photographing section is constant and the movable lens section moves between the fixed lens section and the photographing section.

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