JP2003315678A - Ring illuminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ring illuminator which has a decreased number of installed light emitting diodes by improving illumination efficiency and is then made small-sized and low-cost. <P>SOLUTION: The ring illuminator is equipped with a plurality of light emitting diodes 20 which are arranged in a ring shape around the optical axis 1A of an optical system 1 and emit light in a nearly concentric shape and in a direction nearly parallel to the optical axis 1A, a lens array 30 having a plurality of condenser lenses 31 arrayed in front of and a specified interval away from the light emitting diodes 20 in the lighting direction so that they correspond to the respective light emitting diodes 31, and an optical element 40 which converges the illumination light in front of the lens array 30 in the lighting direction, thereby the illumination light can be converged within a specified lighting range. The illumination efficiency can, therefore, be improved, so that the number of installed light emitting diodes 20 is decreased to make the illuminator small-sized and low-cost. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring illuminator used in an optical measuring instrument such as an optical microscope or an image measuring instrument, and more particularly to an improvement of a ring illuminator using a light emitting diode (LED) as a light source. .

[0002]

2. Description of the Related Art An optical microscope optically forms an image of a measurement site of an object to be measured by an optical system, and an image for inspecting and measuring the shape and dimensions of the object to be measured from the image. In a processing-type measuring machine such as a measuring microscope, a tool microscope, a projector, a three-dimensional image measuring machine, etc., the illumination of the measured object plays a very important role in obtaining a clear image of the measured object.

On the other hand, as an illumination method in an image processing type measuring instrument or the like, a vertical epi-illumination method is known in which an illumination light is applied to an object to be measured from substantially right above. However, the vertical epi-illumination method is often used when measuring an object to be measured whose shape is relatively simple, and an object having a complicated shape, for example, a stepped object having many edge portions is measured. In the measurement, the shadow of the edge portion may not be clearly detected.

Therefore, as a solution to this, by illuminating the object to be measured with illumination light from a direction inclined at a predetermined angle with respect to the optical axis of the optical system, the shadow of the edge portion can be clearly detected. There is a ring lighting device.

Conventionally, as a light source of a ring illuminator, a fiber light source of a type in which illumination light such as a halogen lamp is guided by a fiber is known. However, halogen lamps and the like have drawbacks such as high power consumption, short service life, and slow response speed when controlling lighting or extinction. Further, in such a ring illuminator, as a method of adjusting the brightness and irradiation angle of the illumination light with which the object to be measured is irradiated, there is a method of grouping fiber light sources and controlling lighting or extinction for each group. At this time, prepare lamps for the number of groups of light sources and control lighting or extinction of lamps for each group, or
A means for controlling lighting or extinguishing of the fiber light sources of each group is used by preparing a shutter device or the like for transmitting or blocking light in the middle or the end of the fiber. However, such a method requires a large number of lamps, and
Since the structure becomes complicated, there is a problem that the lighting device becomes large and the manufacturing cost increases.

On the other hand, in recent years, a light emitting diode (LED) has been
Due to its features such as high-speed response and long life, it is being used as a light source in various fields. Then, a ring lighting device using a light emitting diode has been considered as a light source capable of solving the above-mentioned drawbacks of the halogen lamp or the like and controlling the turning on or off individually.

For example, there is a ring illuminator disclosed in Japanese Patent Laid-Open No. 10-54940. This ring lighting device includes a large number of light emitting diodes as a light source, and these light emitting diodes are concentrically arranged in a plurality of circular rows (five rows in the embodiment of the publication), and each light emitting diode emits light. The orientation is determined so that the direction is toward the object to be measured. As a modification of the light-collecting method, the publication discloses a method in which the light-emitting direction of each light-emitting diode is oriented parallel to the optical axis, a Fresnel lens is arranged in front of the light-emitting direction, and the light is condensed on the DUT. ing. Further, in the ring lighting device of the publication, the plurality of light emitting diodes are
Each circular row and a section (8 sections in the embodiment of the publication) zoned in a fan shape in the circumferential direction are grouped in a matrix, and it is possible to control lighting or extinguishing for each group. Therefore, by using a light emitting diode for the light source, the useful life can be extended and
Since a plurality of light emitting diodes arranged can be controlled to be turned on or off for each group, it is possible to appropriately adjust the light distribution to the object to be measured.

[0008]

However, since the light emitting diode itself has a relatively low brightness and its emitted light is emitted with a unique divergence angle, the light emitting diode is irradiated by the time it reaches the object to be measured. It has a drawback that the range is expanded and the illuminance at the position of the object to be measured becomes low.

Therefore, in the illuminating device disclosed in the above-mentioned publication, the light emitting diode is peculiar to either the method of directing the light emitting direction of the light emitting diode to the object to be measured or the method of converging light using the Fresnel lens. It is difficult to obtain a high illuminance because the divergence angle cannot be corrected and the irradiation range of the illumination light is expanded. Therefore, in order to obtain the same level of illuminance as that of a fiber light source type lighting device using a halogen lamp or the like as a light source, a large number of light emitting diodes must be arranged, and the lighting device becomes large and the manufacturing cost increases. There is a problem of doing. Furthermore, when the number of light emitting diodes installed increases, the heat generated from the light emitting diodes affects the measuring device, resulting in a decrease in measurement accuracy and a problem that power consumption increases because power consumption increases.

An object of the present invention is to provide a ring illuminator which can reduce the number of light emitting diodes to be installed by improving the illumination efficiency, and can achieve downsizing and cost reduction.

[0011]

In order to achieve the above object, the ring lighting device of the present invention adopts the following configuration.
The ring illuminator according to claim 1 of the present invention is a ring illuminator arranged in a ring shape around an optical axis of an optical system, wherein the ring illuminator is arranged substantially concentrically with respect to the optical axis. A plurality of light emitting diodes that emit light in one light emitting direction substantially parallel to the light emitting direction, and a plurality of light emitting diodes that are arranged in front of the light emitting direction at a predetermined distance from the light emitting diodes and are arranged corresponding to the respective light emitting diodes. A lens array having a condensing lens, and an optical element arranged in front of the lens array in the light emitting direction and condensing the illumination light passing through the condensing lens at a predetermined position. .

According to the present invention having this structure, the illumination light emitted from the light emitting diode is condensed by the condenser lens of the lens array arranged in front of the light emitting diode, and is placed in a predetermined position by the optical element arranged further in front. Because it is irradiated,
Irradiation light can be concentrated in a predetermined range regardless of the divergence angle specific to the light emitting diode. Therefore, since the lighting efficiency can be improved, the number of light emitting diodes to be installed can be reduced, and the size and cost of the lighting device can be reduced.
Also, by reducing the number of light emitting diodes installed,
The influence of heat generated from the light emitting diode on the measuring device and the like can be reduced, and the power consumption is reduced, so that the power cost can be reduced.

A ring illuminator according to a second aspect is the ring illuminator according to the first aspect, wherein a distance between the light emitting diode and the condenser lens is substantially equal to a focal length of the condenser lens. It is characterized by According to this configuration, the light emitting diode at the focal position of the condenser lens and the irradiation target placed at the focal position of the optical element are optically conjugated, that is, the light is condensed by the optical element. The size of the illumination range is determined by the ratio of the outer diameter of the light emitting diode to the focal length of the condenser lens and the focal length of the optical element. The illumination range can be set according to a certain object to be measured, and since the illumination light does not spread outside the set illumination range, the object to be measured can be efficiently illuminated.

The ring illuminator according to claim 3 is the ring illuminator according to claim 1 or 2, wherein:
The lens array and the optical element are modularized, and are detachably attached to an illumination device main body to which the plurality of light emitting diodes are fixed. According to this configuration, the condenser lens and the optical element having various focal lengths have various focal lengths according to the size and shape of the object to be measured, which is the object to be irradiated, other characteristics, and the type of the objective lens that constitutes the optical system. This modularized lens array and optical element can be easily replaced by selecting from a combination and preparing a modularized one in advance, so that the illumination range and illumination angle during measurement can be adjusted appropriately. It can be set and the measurement can be performed quickly and accurately.

A ring illuminator according to a fourth aspect is the ring illuminator according to any one of the first to third aspects, wherein the optical element is a Fresnel lens. According to this configuration, by using the Fresnel lens which is a general-purpose optical element, the illuminating device can be manufactured at low cost, and the Fresnel lens is thin and lightweight, so that the illuminating device can be made compact and compact. The weight can be reduced.

A ring illuminator according to a fifth aspect is the ring illuminator according to any one of the first to third aspects, wherein the optical element is a substantially donut-shaped lens having a hole in a central portion. It is characterized by According to this configuration, by using a lens that is a general-purpose optical element, a lighting device can be manufactured at low cost, and if a lens having high transmittance and high accuracy is used, the transmission loss of illumination light is small, and Since the illumination light can be accurately concentrated on the illumination range, the illumination efficiency can be further improved. Also, through the hole provided in the center of the lens, the objective lens as the optical system can penetrate the ring illuminator,
Alternatively, since the reflected light from the measured object as the irradiated object can reach the objective lens without being blocked, the measured object can be reliably measured.

A ring illuminator according to a sixth aspect is the ring illuminator according to any one of the first to third aspects, in which the optical elements are formed in a substantially concentric shape and are arranged in accordance with a radial position. It is characterized in that it is a prism having an incident surface having a predetermined inclination. According to this configuration,
By appropriately setting and processing the angle of the substantially concentric incident surface provided on the prism, the focusing efficiency of the prism can be improved, so that the illumination efficiency can be further improved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a ring illuminating device according to the present invention will be described below in detail with reference to the drawings. In the following description, the same constituents will be given the same reference numeral, and the description thereof will be omitted or simplified. 1 to 3 show a ring lighting device 10 according to a first embodiment of the present invention, and FIGS. 4 and 5 show ring lighting devices 50 and 60 according to the second and third embodiments. Are shown respectively.

[First Embodiment] FIG. 1 is an overall perspective view of a ring lighting device 10, FIG. 2 is a sectional view thereof, and FIG.
[FIG. 3] is a bottom view in which a part thereof is shown in cross section. 1 to 3
In the above, the ring illuminator 10 is used for illuminating an object to be measured 3 (workpiece) on a measuring table 2 of an image measuring device (not shown), and is attached to an objective lens 1 as a magnifying optical system of the measuring device or the like. There is. The image measuring device drives and controls the measuring table 2 in two orthogonal directions in the horizontal plane, that is, in the left and right and front and rear directions in FIG. 2 by a driving device (not shown), and also in the vertical direction, that is, in FIG.
By controlling the drive in the middle and up and down directions, it is possible to adjust the position and the measurement distance suitable for the measured portion of the DUT 3.

The ring illuminating device 10 surrounds the objective lens 1 and is formed inside the case 11 as an illuminating device main body formed in a ring shape around the optical axis 1A of the objective lens 1. A plurality of light emitting diodes 20 and a lens array 30 and a Fresnel lens 40 as an optical element that covers the lower part of the case 11 in FIG. 2 are provided. In addition, the objective lens 1 in FIG.
And the vertical position is determined by separating a predetermined measurement distance. At this time, the Fresnel lens 40 of the ring illumination device 10 attached to the objective lens 1 is separated from the DUT 3 by the distance D2.

The case 11 includes inner and outer side plates 11A and 11B which are cylindrically formed from a metal plate material and the like, and a top plate 11C which is formed into a donut shape along the edges of the side plates 11A and 11B. In combination, they are formed in a ring shape that opens downward in FIG. Inner side plate 11A
Has an inner diameter that allows the objective lens 1 to be inserted with a margin, and the case 11 is provided with a mounting portion (not shown) for mounting the ring illumination device 10 on the objective lens 1 with the objective lens 1 inserted. Has been. As this attachment part, for example, three screws supported so as to be able to move forward and backward toward the objective lens 1 can be applied.

The light emitting diode 20 emits white light, and the emitted illumination light has a divergence angle of a predetermined angle (for example, 2).
A condenser lens is attached to the tip of the emission direction (downward direction in FIG. 2) so that it becomes 0 °, and a predetermined outer diameter (for example,
5 mm) and a wiring 23 connected to a control circuit and a power source (not shown). Such light-emitting diodes 20 are arranged in a triple concentric shape centered on the optical axis 1A on the same plane substantially orthogonal to the optical axis 1A and fixed inside the case 11.

A lens array 30 is arranged in front of each light emitting diode 20 in the light emitting direction at a position separated from the light emitting point 21 of the light emitting diode 20 by a predetermined distance D1. The lens array 30 is made of transparent glass, and a plurality of condenser lenses 31 having a focal length F1 are arranged in a substantially concentric circle corresponding to the light emitting diode 20 and are integrally formed.

A Fresnel lens 40 having a focal length F2 is attached to the lower end of the case 11 in FIG. The Fresnel lens 40 is made of a transparent synthetic resin and has a lens array 3
A plurality of concentric circular grooves having the optical axis 1A as the approximate center is formed on the surface facing 0 (the upper surface in FIG. 2). The angle of the incident illumination light is changed to the position of the focal length F2. It has a function of converging illumination light.

Further, the lens array 30 and the Fresnel lens 40 are modularized in advance according to the focal length F1 of the condenser lens 31 and the focal length F2 of the Fresnel lens 40, and a plurality of these modularized combinations are prepared. There is. These modularized lens array 30 and Fresnel lens 40 have three screw holes 12 provided on the side plate 11B outside the case 11, and holes provided on the outer periphery of the Fresnel lens 40 corresponding to their positions. Screwed through.

Next, the ring lighting device 1 according to the present embodiment.
The operation of 0 will be described. The position of the objective lens 1 is adjusted to a measuring distance set according to the size and shape of the DUT 3 and the measuring range. In setting the required illumination range, first, based on the position of the objective lens 1, the distance D2 between the Fresnel lens 40 of the ring illumination device 10 and the DUT 3 is measured.
And the focal length F2 of the Fresnel lens 40 is set to be equal to this distance D2. Next, by setting the focal length F1 of the condenser lens 31 so as to be equal to the distance D1 between the light emitting point 21 of the light emitting diode 20 and the lens array 30, the DUT 3 and the light emitting diode 20 are optically separated. Is conjugated to. Therefore, since the size of the illumination range can be set by the product of the outer diameter of the light emitting unit 22 and the ratio of the focal length F2 and the focal length F1, the appropriate focal lengths F1 and F2 are selected from a plurality of sets prepared in advance. The module of the lens array 30 and the Fresnel lens 40 including is selected. Selected lens array 30 and Fresnel lens 4
By setting the ring illumination device 10 with the module No. 0 attached to the objective lens 1 and performing illumination, the illumination light is condensed within the illumination range set for the DUT 3.

Further, in order to adjust the irradiation angle of the illumination light with which the DUT 3 is irradiated, the focal length F2 according to the irradiation angle is adjusted.
And the lens array 30 having the focal length F1 that matches the required illumination range, and the ring lighting device 10 is attached so that the focal length F2 and the distance D2 are equal. That is, when the irradiation angle of the illumination light is reduced, the long focal length F2
When the Fresnel lens 40 having the focal length F2 is selected to increase the irradiation angle of the illumination light, the Fresnel lens 40 having the short focal length F2 is selected. By attaching a module having a combination of the selected Fresnel lens 40 and the lens array 30 having the focal length F1 of the condenser lens 31 suitable for the set illumination range, the irradiation angle with respect to the required illumination range The illumination light is adjusted.

Therefore, according to this embodiment, the following effects can be obtained. (1) The illumination light emitted from the light emitting diode 20 is condensed by the condensing lens 31 of the lens array 30 arranged in the front in the light emitting direction, and is irradiated to the DUT 3 by the Fresnel lens 40 arranged further in the front. Therefore, regardless of the divergence angle specific to the light emitting diode 20, the illumination light can be improved by concentrating the illumination light in a predetermined range, so that the number of the light emitting diodes 20 to be installed can be reduced and the size of the ring lighting device 10 can be reduced. And cost reduction can be achieved.

(2) Since the number of the light emitting diodes 20 installed is smaller than that in the conventional technique, the heat generated from the light emitting diodes 20 can reduce the influence on the image measuring device and the like, and the power consumption is low and the power cost is reduced. it can.

(3) Since the size of the illumination range can be set by the product of the outer diameter of the light emitting portion 22 and the ratio of the focal length F2 and the focal length F1, the condenser lens 31 and the Fresnel lens 40 are appropriately selected. By doing so, the illumination range corresponding to the DUT 3 can be obtained, and the illumination light does not spread outside the set illumination range, so that the DUT 3 can be efficiently illuminated.

(4) The lens array 30 and the Fresnel lens 40 are modularized and a plurality of sets are prepared. The lens array 30 and the Fresnel lens 40 can be detachably attached to the case 11 by screwing. Focal length F
By selecting the set of the lens array 30 including 1 and F2 and the Fresnel lens 40, the illumination range can be appropriately set, and the measurement can be performed quickly and accurately.

(5) Modular lens array 3
0 and the appropriate focal length F from the set of Fresnel lens 40
By selecting the combination including 1 and F2, the illumination angle can be appropriately set according to the DUT 3, so that in the case of the DUT 3 having a three-dimensional shape, the edge can be clearly projected. Therefore, the measurement accuracy can be improved.

(6) By using the general-purpose Fresnel lens 40 as the optical element for converging the illumination light on the DUT 3, the illuminating device can be manufactured at low cost, and the Fresnel lens 40 has a large thickness. Since the ring lighting device 10 is thin and light, the size and weight of the ring lighting device 10 can be reduced.

[Second Embodiment] Next, a second embodiment of the present invention will be described. FIG. 4 shows a cross-sectional view of the ring lighting device 50 according to the second embodiment. The ring illuminating device 50 is different from the above-described first embodiment only in that a lens 51 as an optical element is used instead of the Fresnel lens 40, and other configurations are the same as those in the first embodiment. It is the same. The lens 51 attached to the lower end of the case 11 in FIG. 4 is made of transparent glass, and the hole 52 is provided substantially at the center of the lens with the optical axis 1A as the center and the thickness becoming thinner toward the outer periphery. It is processed into a substantially donut shape. Further, the lens 51 passes through the condensing lenses 31 arranged substantially concentrically, refracts the illumination light incident from the position corresponding to each condensing lens 31, and condenses the illumination light at the position of the focal length F3. Have a function to do. In FIG. 4, the ring illumination device 50 is attached to the objective lens 1 so that the lens 51 and the DUT 3 are separated by the distance D3.

The lens array 30 and the lens 51 have a focal length F1 of the condenser lens 31 and a focal length F of the lens 51.
3 is modularized in advance, and a plurality of modularized combinations are prepared. These modularized lens array 30 and lens 51 are
It is detachably attached to the case 11. Further, the focal length F3 of the lens 51 is made equal to the distance D3 between the DUT 3 and the lens 51, and the focal length F1 of the condenser lens 31 is set.
By setting each of the focal lengths F1 and F3 so as to be equal to the distance D1 between the light emitting point 21 and the lens array 30, and modularizing the same, as in the case of the first embodiment described above.
The illumination range and illumination angle suitable for the DUT 3 can be adjusted.

Therefore, according to this embodiment, the following effect can be obtained in addition to the effect of (2) described above. (7) The illumination light emitted from the light emitting diode 20 is condensed by the condensing lens 31 of the lens array 30 arranged in the front of the light emitting direction, and irradiated to the DUT 3 by the lens 51 arranged further in the front. Therefore, regardless of the divergence angle specific to the light emitting diode 20, the illumination light can be improved by concentrating the illumination light in a predetermined range, so that the number of the light emitting diodes 20 installed can be reduced and the ring lighting device 5 can be provided.
0 size reduction and cost reduction can be achieved.

(8) Since the size of the illumination range can be set by the product of the outer diameter of the light emitting portion 22 and the ratio of the focal length F3 and the focal length F1, the condenser lens 31 and the lens 51.
By appropriately selecting, the illumination range according to the DUT 3 can be obtained, and the illumination light does not spread outside the set illumination range, so that the DUT 3 can be illuminated efficiently.

(9) Lens array 30 and lens 51
Are modularized and a plurality of sets are prepared, and can be detachably attached to the case 11 by screwing. Therefore, appropriate focal lengths F1 and F3 can be set according to a required illumination range.
By selecting the set of the lens array 30 and the lens 51 including the, the illumination range can be appropriately set, and the measurement can be performed quickly and accurately.

(10) Modular lens array 3
0 and lens 51 are set to appropriate focal lengths F1, F3
Since the illumination angle can be appropriately set according to the object to be measured 3 by selecting a combination including, the measurement accuracy can be improved by making the edges of the object 3 having a three-dimensional shape clearly stand out. Can be improved.

(11) Lens 51 which is a general-purpose optical element
The ring illuminator 50 can be manufactured at low cost by using, and if the lens 51 having high transmittance and high accuracy is used, the transmission loss of the illumination light is small and the illumination light is accurately concentrated in the illumination range. Therefore, it is possible to further improve the illumination efficiency.

(12) Hole 52 provided at the center of lens 51
Through, the objective lens 1 can penetrate the ring illumination device 50 or the reflected light from the DUT 3 can reach the objective lens 1 without being blocked, so that the DUT 3 can be reliably measured. .

[Third Embodiment] Next, a third embodiment of the present invention will be described. FIG. 5 shows a cross-sectional view of the ring lighting device 60 according to the third embodiment. The ring illuminator 60 is different from the first embodiment described above only in the portion using a prism 61 having a polygonal cross section as an optical element instead of the Fresnel lens 40.
Other configurations are similar to those of the first embodiment. Figure 5
The prism 61 attached to the lower end of the middle case 11
Is made of transparent glass and is processed into a polygonal cross-section provided with an entrance surface 62 having a triple concentric inclination with respect to the optical axis 1A. Each incident surface 62 is set so that the angle with the optical axis 1A becomes smaller as the distance from the optical axis 1A increases, and has a function of refracting the incident illumination light and condensing the illumination light at the position of the focal length F4. ing. In FIG. 5, the ring illumination device 60 is attached to the objective lens 1 so that the prism 61 and the DUT 3 are separated by a distance D4.

The lens array 30 and the prism 61 are
A plurality of modularized combinations are prepared in advance according to the focal length F1 of the condenser lens 31 and the focal length F4 of the prism 61. These modularized lens array 30 and prism 6
1 is detachably attached to the case 11. Further, the focal length F4 of the prism 61 is made equal to the distance D4 between the DUT 3 and the prism 61, and the focal length F1 of the condenser lens 31 is made equal to the distance D1 between the light emitting point 21 and the lens array 30. By setting each of the focal lengths F1 and F4 to and modularizing, the illumination range and the illumination angle suitable for the DUT 3 can be adjusted as in the case of the first embodiment described above.

Therefore, according to this embodiment, the following effect can be obtained in addition to the effect of (2) described above. (13) The illumination light emitted from the light emitting diode 20 is condensed by the condenser lens 31 of the lens array 30 arranged in the front in the light emitting direction, and is irradiated to the DUT 3 by the prism 61 arranged further in the front. Therefore, regardless of the divergence angle specific to the light emitting diode 20, the illumination light can be improved by concentrating the illumination light in a predetermined range, so that the number of the light emitting diodes 20 installed can be reduced and the ring lighting device 60 can be miniaturized. And cost reduction can be achieved.

(14) Since the size of the illumination range can be set by the product of the outer diameter of the light emitting section 22 and the ratio of the focal length F4 and the focal length F1, the condensing lens 31 and the prism 6 can be set.
By appropriately selecting 1, the illumination range corresponding to the DUT 3 can be obtained, and the illumination light does not spread outside the set illumination range, so that the DUT 3 can be illuminated efficiently.

(15) Lens array 30 and prism 6
1 is modularized and a plurality of sets are prepared, and can be detachably attached to the case 11 by screwing. Therefore, appropriate focal lengths F1 and F can be set according to a required illumination range.
By selecting the set of the lens array 30 and the prism 61 each including No. 4, the illumination range can be appropriately set, and the measurement can be performed quickly and accurately.

(16) Modular lens array 3
0 and the pair of prisms 61, the appropriate focal lengths F1, F
By selecting a combination including 4, the illumination angle can be appropriately set according to the DUT 3, so that in the case of a DUT 3 having a three-dimensional shape, etc. The accuracy can be improved.

(17) By appropriately setting and processing the angle of the substantially concentric circular incident surface 62 provided on the prism 61, the light collection efficiency of the prism 61 can be improved and the illumination efficiency of the ring lighting device 60 can be improved. It is possible to improve.

The present invention is not limited to the above-described embodiments, but includes modifications and improvements as long as the object of the present invention can be achieved. For example,
In each of the above-described embodiments, the ring illumination device used in the image measuring device has been described, but it may be used in a measuring microscope, a tool microscope, a projector, a three-dimensional image measuring device, or the like.
Further, in each of the above-described embodiments, the ring illuminator is attached to the objective lens 1, but the present invention is not limited to this, and may be attached to the main body of the measuring device or the measuring stand, or separately from these measuring devices or the like. A member for supporting the ring lighting device may be provided and attached to this member. Further, the mounting method is not limited to the method using three screws supported so as to be able to move forward and backward toward the objective lens 1, but can be applied as long as it is a method capable of appropriately setting the distance between the ring illuminator and the object to be measured, Further, it may be provided with a means for moving along the optical axis of the optical system.

In each of the above-described embodiments, the light emitting diodes 20 are arranged in a triple concentric shape, but the arrangement is not limited to this, and a single circular arrangement or a double, quadruple or more overlapping shape is provided. The arrangement may be substantially concentric, or may be radial or grid. Further, in each of the above-described embodiments, the lens array 30, the lens 51, and the prism 61.
Is made of transparent glass, but is not limited to this and may be made of synthetic resin. Although the Fresnel lens 40 is made of transparent synthetic resin, it is not limited to this and may be made of glass.

[0051]

As described above, according to the ring illuminator of the present invention, it is possible to reduce the number of light emitting diodes to be installed by improving the illumination efficiency, and to reduce the size and cost. Can be expected.

[Brief description of drawings]

FIG. 1 is a perspective view showing a ring lighting device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the ring lighting device according to the embodiment.

FIG. 3 is a bottom view of the ring lighting device according to the embodiment.

FIG. 4 is a sectional view of a ring lighting device according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a ring lighting device according to a third embodiment of the present invention.

[Explanation of symbols]

1 Objective lens (optical system) 1A optical axis 11 Case (lighting device body) 20 light emitting diode 30 lens array 31 Condensing lens 40 Fresnel lens (optical element) 51 lens (optical element) 52 holes 61 Prism (optical element) 62 plane of incidence

Claims (6)

[Claims] 1. A ring illuminator arranged in a ring shape around an optical axis of an optical system, wherein the ring illuminator is arranged substantially concentrically with respect to the optical axis and emits light in one direction substantially parallel to the optical axis. A plurality of light emitting diodes that emit light as a light source, and a lens array that has a plurality of condenser lenses that are arranged in front of the light emitting direction at a predetermined distance from the light emitting diodes and that are arranged corresponding to the respective light emitting diodes. A ring illuminator, comprising: an optical element that is disposed in front of the lens array in the light emitting direction and that condenses the illumination light that has passed through the condenser lens at a predetermined position. 2. The ring lighting device according to claim 1, wherein a distance between the light emitting diode and the condenser lens is substantially equal to a focal length of the condenser lens. apparatus. 3. The ring lighting device according to claim 1, wherein the lens array and the optical element are modularized and can be detachably attached to a lighting device main body to which the plurality of light emitting diodes are fixed. A ring illuminator characterized by being attached. 4. The ring illuminator according to claim 1, wherein the optical element is a Fresnel lens. 5. The ring illuminator according to claim 1, wherein the optical element is a substantially donut-shaped lens having a hole in a central portion thereof. 6. The ring illuminating device according to claim 1, wherein the optical element includes an incident surface formed in a substantially concentric shape and having a predetermined inclination according to a radial position. A ring illuminator, which is a prism.