KR100996881B1 - Integrating sphere - Google Patents

Abstract

The present invention relates to an integrating sphere, and more particularly, to an integrating sphere in which light measurement errors are reduced by diffusing light flowing into the integrating sphere.
The present invention provides an integrating sphere for measuring optical characteristics of a light source, the integrating sphere body having a hollow portion and a light receiving hole connected to the hollow portion; And a diffusion plate provided in the light receiving hole and diffusing the light flowing into the hollow part from the light receiving hole.

Description

Integral sphere {INTEGRATING SPHERE}

The present invention relates to an integrating sphere, and more particularly, to an integrating sphere in which light measurement errors are reduced by diffusing light flowing into the integrating sphere.

An integrating sphere is a spherical device having a hollow portion inside, and is an apparatus that receives light into the hollow portion and measures its characteristics. The inner surface of the integrating sphere is made of or coated with a material that effectively diffuses light. As a result, the light flowing into the hollow portion of the integrating sphere is continuously diffused in the integrating sphere, and thus the intensity and optical characteristics of the incoming light are averaged in the hollow portion.

The main configuration of the integrating sphere is shown in FIG.

A hollow part 2 is formed inside the integrating sphere 1, and a light receiving hole 3 for receiving light emitted from the light source L is provided below the integrating sphere 1. In addition, a measuring hole (4; 5) is provided on the inner surface of the integrating sphere (1), and the light is introduced into the optical characteristic measuring device (6; 7) through the measuring hole (4; 5) to measure the optical characteristics. do. The light source L is seated on the holding member 10.

The kind of the light source L is not particularly limited, and for example, an LED (Light Emitting Diode) may be used. LED is a kind of light emitting device using a semiconductor that converts electricity into light, also called a Luminescent diode.

2A and 2B show the radiation pattern of the LED. These light emission patterns indicate the intensity of light according to the emission angle when the LED is located at the O point. In this case, the light intensity is expressed only dimensionally according to the emission angle, so it is displayed dimensionlessly. In general, various kinds of light emission patterns are displayed depending on the types of LEDs, and the actual light emission patterns are slightly different for each LED chip even though they are the same type. For example, according to the light emission pattern of the LED illustrated in FIG. 2A, it can be seen that the chief ray P having the highest light intensity is formed in the upper vertical direction of the LED, that is, in the 0 degree direction. On the other hand, according to the light emission pattern of the LED illustrated in FIG. 2B, it can be seen that the chief rays P1 and P2 are formed to be spaced apart by a predetermined angle with respect to the upper vertical direction of the LED.

However, when the optical characteristics of the same LED chip, such as the intensity of light, are measured several times by the above-described conventional integrating sphere, there is a variation in the measured value every measurement. This measurement error is called PO deviation. PO deviation varies depending on the type of LED, but it is about 5% and largely reaches 7-8%.

The main cause of such PO deviation is considered to be that a relative position error occurs between the LED, which is the light source L, and the integrating sphere.

For example, even when the light emission pattern of the LED is the same as that shown in FIG. 2A, the case where the support member 10 on which the LEDs L and the LEDs L are seated is in the correct position When the supporting member 10 on which the light source L and the LED L are mounted has a tilt error by a predetermined angle? (See Fig. 3B), the intensity of light entering the integrating sphere in both cases varies depending on the radiation angle They are different. In FIG. 3B, the LED and the support member 10, which are the light source L, are exaggerated to show an inclination angle θ with respect to the vertical line. In addition, even when the support member 10 is in the correct position, a deviation occurs in the shape or mounting angle of the LED, and as a result, an inclination error may occur between the integrating sphere and the LED.

As such, when the LED has an inclination error with respect to the integrating sphere, the positions of the chief rays are different, which causes a difference in the number of times the chief rays are reflected from the inner side until they enter the measuring hole in the integrating sphere. Each reflection causes a certain amount of loss, so the difference in the number of reflections causes a variation in the measured value. As such, since the light emission pattern of the LED is not uniform according to the radiation angle, even if the characteristics of the light are averaged in the integrating sphere, deviations occur in the optical characteristics actually measured. In addition, when the LED has an inclination error with respect to the integrating sphere, more light may be lost without being introduced into the integrating sphere, which may cause a deviation in the measured optical characteristics.

This deviation causes a great difficulty in accurately measuring and classifying the optical characteristics of the LED chip, which in turn increases the defect rate of the product using the LED chip.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an integrating sphere in which the measurement error of light is reduced.

In order to achieve the above object, the present invention, the integrating sphere for measuring the optical characteristics of the light source, the integrating sphere body having a hollow portion and the light receiving hole connected to the hollow portion; And a diffusion plate provided in the light receiving hole and diffusing the light flowing into the hollow part from the light receiving hole.

In the present invention, the integrating sphere body may be substantially spherical. In addition, the integrating sphere body may be provided with a measuring hole for connecting the optical characteristic meter.

In addition, the optical characteristic meter may be a photo detector or a spectrometer. In addition, a baffle may be provided on the inner surface of the integrating sphere body to prevent directing light from the light receiving hole directly to the measurement hole.

In the present invention, the diffusion plate may be a light transmissive substrate whose surface is polished by micro sanding. Here, the light transmissive substrate may be a glass or a resin substrate.

In the present invention, the diffusion plate may be formed of a light transmissive substrate and a light diffusion layer formed on the light transmissive substrate. Here, the light transmissive substrate may be a glass substrate, and the light diffusion layer may be a resin layer including organic or inorganic diffusion particles.

The light diffusing layer may be a patterned convex portion or a concave portion. Here, the patterned convex portion may be a plurality of micro-convex lenses of a hemispherical shape, a semi-cylindrical shape, a prismatic pillar, or a pyramid shape. In addition, the patterned concave portion may be a plurality of hemispheres, semi-cylindrical, prismatic, or pyramidal micro-concave lens is arranged.

In addition, the light diffusion layer may be formed in a plurality of layers on the light transmissive substrate.

In the present invention, the diffusion plate may be a light transmissive substrate including organic or inorganic diffusion particles. Here, the light transmissive substrate may be a resin substrate.

In addition, the diffusion plate may be a fly eye lens or a prism sheet.

In addition, the diffusion plate may be one having a constant high transmittance in the wavelength range of 200 nm to 1000 nm. In addition, the diffusion plate is magnesium fluoride (MgF ₂ ), calcium fluoride (CaF ₂ ), fused silica glass, borosilicate crown (BK7) glass, crystal quartz, polymethyl methacrylate (PMMA), It may be made of any one or more materials of sapphire.

Finally, the light source may be an LED chip.

According to the integrating sphere according to the present invention, by diffusing the light flowing into the hollow portion provided inside the integrating sphere, the measurement error of the light can be reduced.

1 is a cross-sectional view schematically showing a conventional integrating sphere.
2A and 2B show light emission patterns of LEDs.
3a and 3b show the change in the light emission pattern according to the mounting position error of the LED.
4 is a cross-sectional view schematically showing an integrating sphere according to the present invention.
5 shows the light intensity profile before and after passing through the diffuser plate.
6 is a cross-sectional view and an enlarged cross-sectional view showing a diffusion plate according to an embodiment of the present invention.
7A to 7F are cross-sectional views and perspective views illustrating a diffusion plate according to another embodiment of the present invention.
8A and 8B are perspective views showing a diffuser plate formed as a fly's eye lens.
9A and 9B are sectional views and a perspective view showing a diffusion plate formed as a prism sheet.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

4 is a cross-sectional view schematically showing an integrating sphere according to the present invention. As shown, the integrating sphere 100 has an integrating sphere body 110 and a diffusion plate 120 coupled to the integrating sphere body 110.

A hollow portion 111 is provided inside the integrating sphere body 110. The hollow part 111 is spherical so that the characteristics of the light introduced into the hollow part 111 may be homogenized by diffuse reflection, and thus, the integrating sphere body 110 is also substantially spherical.

The integrating sphere body 110 may be formed by, for example, coating a diffuse reflection layer having a high reflectance on the inner surface of the metal shell. The diffuse reflection layer may be made of a material including, for example, polytetrafluoroethylene (PTFE). However, the material of the diffuse reflection layer is not limited to PTFE, and may be made of a material including a polymer such as polychlorotrifluoroethylene (PCTFE) or polyvinylidenefluoride (PVDF). As another method, the integrating sphere body 110 may be composed of an inner shell including a diffuse reflection layer and a metallic outer shell coupled to the outer side of the inner shell.

A light receiving hole 112 for introducing light into the hollow part 111 is provided below the integrating sphere main body 110. The light receiving hole 112 may be formed in a circular shape, but the shape thereof is not particularly limited.

The side of the integrating sphere main body 110 is provided with a measuring hole (113; 114) for connecting the optical characteristic measuring device (115; 116). The measuring holes 113 and 114 may be formed in a circular shape, but the shape thereof is not particularly limited. Although two measuring holes 113 and 114 are shown in FIG. 4, one or three or more measuring holes may be provided according to the number of optical characteristic measuring instruments.

The optical characteristics that can be measured using the integrating sphere 100 may be, for example, brightness, wavelength, light flux, illuminance, illuminance, spectral distribution, color temperature, and color coordinates. In addition, the optical characteristic analyzer 115 and 116 may be, for example, a photo detector or a spectrometer. A spectrometer is a device for measuring the spectrum of light, and a light receiving element is a device that detects an optical signal and converts it into an electrical signal. Since the configuration of the spectrometer, the light receiving element, and other optical characteristic measuring instruments is well known, detailed description thereof will be omitted.

Baffles 117 and 118 are provided on the inner surface of the integrating sphere main body 110. The baffles 117 and 118 are provided between the light receiving holes 112 and the measuring holes 113 and 114 to prevent the light flowing from the light receiving holes 112 from being directed directly to the measuring holes 113 and 114. When the light flowing from the light receiving hole 112 directly flows into the measuring holes 113 and 114, the function of the integrating sphere 100 to measure the uniformity of optical characteristics is halved, and the measurement deviation is also increased.

The baffles 117 and 118 may be formed in a half moon shape, but the shape is not particularly limited. In addition, the baffles 117 and 118 are preferably made of the same material as the diffuse reflection layer provided on the inner surface of the integrating sphere body 110, and the baffles 117 and 118 and the integrating sphere body 110 are integrally formed. It is possible.

The diffusion plate 120 is provided in the light receiving hole 112. Specifically, the diffusion plate 120 is installed below the light receiving hole 112 to cover the light receiving hole 112 opened to the outside, and is coupled to the integrating sphere body 120 by a separate holder member 140. . The holder member 140 is a member that couples the diffuser plate 120 to the integrating sphere body 120. For example, the holder member 140 forms a screw thread on the inner surface of the holder member 140, and receives a light receiving hole in the integrating sphere body 112. 112) By forming a screw thread in the portion drawn outward, the holder member 140 and the integrating sphere main body 120 can be screwed. As long as it has a function of connecting the diffusion plate 120 to the integrating sphere body 120, there is no particular limitation on the shape or coupling method of the holder member 140. In addition, the diffusion plate 120 and the holder member 140 may be integrated.

The function of the diffusion plate 120 will be described with reference to FIG. 5. 5 shows the light intensity profile before and after passing through the diffuser plate. As shown in FIG. 5, it is assumed that an LED L as a light source is mounted on the support member 10, and the diffusion plate 120 is positioned on the upper side thereof. In addition, it is assumed that the light emission pattern of the LED L is as shown in FIG. 2A. The integrating sphere main body connected to the upper side of the diffusion plate 120 is omitted.

Prior to passing through the diffuser plate 120, the light intensity profile, for example on line A, is shown at G1. The horizontal axis of G1 represents distance, and the vertical axis represents relative magnitude of light intensity. In this case, on the A line, the intensity profile of the light shows a Gaussian distribution. That is, the farther away from the LED (L), the smaller the intensity of the light, which corresponds to the smaller the intensity of the light as the radiation angle in the direction of 90 degrees or -90 degrees in Figure 2a.

After passing through the diffuser plate 120, the light intensity profile, for example on line B, is shown in G2. As in G1, the horizontal axis of G2 represents the distance and the vertical axis represents the relative magnitude of the light intensity. In this case, it can be seen that on the line B, the light intensity has a uniform value in a predetermined region including the center portion. That is, when light passes through the diffuser plate 120, diffusion occurs at each point of the diffuser plate 120, so that each point of the diffuser plate 120 acts as a separate light source, and thus the light intensity of G2. As can be seen from the profile, the difference in light intensity with the angle of radiation cancels out substantially. In other words, after passing through the diffusion plate 120, the light is emitted from a light source having a uniform radiation intensity regardless of the radiation angle.

Accordingly, even when the LED L or the supporting member 10 on which the LED L is mounted has a positional error with respect to the integrating sphere as shown in FIG. 3B, a measurement error does not occur. When the diffusion plate 120 is used, the PO deviation is reduced to about 1%.

On the other hand, the diffusion plate 120 should have a function of transmitting light as well as a function of diffusing light. If the transmittance is low, the actual optical properties may not be measured. Therefore, the diffusion plate 120 should have a light transmittance such that at least an optical signal of more than the background noise of the optical characteristic measuring instrument is transmitted to the optical characteristic measuring instrument. In particular, in the case of LEDs, since the wavelength range of the optical characteristic corresponds to 200 nm to 1000 nm, the transmittance of the diffusion plate 120 preferably has a constant high value in the wavelength range of 200 nm to 1000 nm. To this end, the diffusion plate may be made of magnesium fluoride (MgF ₂ ), calcium fluoride (CaF ₂ ), fused silica glass, borosilicate crown (BK7) glass, crystal quartz, polymethylmethacrylate (PMMA), It is preferable that it consists of sapphire or other material which satisfy | fills the said transmittance | permeability conditions.

The configuration of the diffusion plate 120 will be described with reference to FIGS. 6 to 9B. FIG. 6 is a cross-sectional view and an enlarged cross-sectional view showing a diffuser plate according to an embodiment of the present invention, FIGS. 7a to 7f are a cross-sectional view and a perspective view showing a diffuser plate according to another embodiment of the present invention, 9A and 9B are sectional views and a perspective view showing a diffusion plate formed as a prism sheet.

As shown in FIG. 6, the diffusion plate 120 may be formed of a light transmissive substrate whose surface is polished by micro sanding. The light transmissive substrate may be a glass or resin substrate. Numerous protrusions 121 are formed on the surface of the diffusion plate 120 polished by micro sanding. Since the protrusion 121 serves as a lens, the light passing through the diffusion plate 120 is diffused and uniformized.

As another example, the diffusion plate 120 may be formed of a light transmissive substrate 122 and a light diffusion layer 123 formed on the light transmissive substrate 122, as shown in FIG. 7A. The light transmissive substrate 122 may be, for example, a glass substrate, and the light diffusion layer 123 may be a resin layer such as acrylic. The light diffusion layer 123 may include a plurality of diffusion particles 124 serving as a lens (see FIG. 7B). Light passing through these diffusion particles 124 is diffused and uniformized. The diffusion particles 124 may be formed of an organic or inorganic material, and have a refractive index different from that of the resin layer forming the light diffusion layer 123 in order to have a light diffusion function. The diffusion particles 124 may be made of a material such as urethane resin, acrylic resin, epoxy resin, olefin resin, polyester resin, alumina, glass, silica, or a mixture thereof. The material of the diffusion particles 124 and the refractive index difference between the diffusion particles 124 and the resin layer and the volume ratio of the diffusion particles 124 to the resin layer can be selected in consideration of the diffusion performance and the transmittance of the diffusion plate 120 .

In the above-described embodiment, the light diffusion layer 123 is formed on the light transmissive substrate 122 in consideration of the mechanical strength of the diffusion plate 120 (see FIG. 7B). It is also possible to have a single layer structure, that is, a light transmissive substrate containing organic or inorganic diffusion particles. In this case, the light transmissive substrate may be a resin substrate.

As another embodiment, the light diffusing layer 123 may include a convex portion or a concave portion on its surface, as shown in FIGS. 7C and 7D. The material of the light diffusion layer 123 is not particularly different from the above-described embodiment, and may be formed of, for example, a glass or resin layer.

The convex portion may be a hemispherical micro convex lens 125 as shown in FIG. 7C. However, the shape of the micro convex lens 125 is not limited to the hemispherical shape, and as long as it is a structure capable of diffusing light such as a semi-cylindrical shape, a prismatic shape, and a pyramid shape, the shape is not particularly limited.

Meanwhile, the concave portion may be a hemispherical micro concave lens 126 as shown in FIG. 7D. However, as in the case of the micro convex lens 125, the shape of the micro concave lens 126 is not limited to the hemispherical shape, but as long as it is a structure capable of diffusing light such as a semi-cylindrical shape, a prismatic shape, and a pyramid shape, There is no special limitation.

The convex portion and the concave portion described above may be arranged on the light transmissive substrate 122 in a predetermined pattern. In addition, in the above embodiment, only a plurality of convex portions are formed on the light transmissive substrate 122, or only a plurality of concave portions are formed on the light transmissive substrate 122, but one light transmissive substrate 122 is formed. The convex part and the concave part may be arranged sequentially or randomly). As long as the light passing through the diffusion plate 120 is diffused and uniformized in this manner, the shape and arrangement of the convex portion and the concave portion are not particularly limited.

As another embodiment, as shown in FIGS. 7E and 7F, it is also possible to form a light diffusion layer in multiple layers on a light transmissive substrate. For example, as illustrated in FIG. 7E, the first light diffusing layer 127 and the second light diffusing layer 128 may be sequentially formed above the light transmissive substrate 122. The first light diffusing layer 127 and the second light diffusing layer 128 are semi-cylindrical microlenses that extend in cross directions, and in this case, the first light diffusing layer 127 and the second light diffusing layer 128 have a refractive index. It should be made of different materials.

Alternatively, a third light diffusing layer 129 may be formed on the light-transmitting substrate 122 and a fourth light-diffusing layer 130 may be formed on the light-transmitting substrate 122, as shown in FIG. 7F Do. The third light diffusing layer 129 and the fourth light diffusing layer 130 are semi-cylindrical micro lenses whose extension directions cross each other. In this case, unlike the embodiment illustrated in FIG. The four light diffusing layers 130 may be formed of the same material.

8A and 8B show fly eye lenses 131 and 132. It is also possible to use the fly eye lenses 131 and 132 as diffusion plates. 9A and 9B, a prism sheet 133 is shown, and it is also possible to use such a prism sheet as a diffusion plate. These fly-eye lenses and prism sheets have the same function as those of the diffuser plate 120 shown in FIGS. 7A to 7F in that a structure serving as a lens is formed on a surface thereof.

As mentioned above, although the Example of this invention was described, it is clear that a change of a structure, addition, and substitution by an equivalent can be carried out within the range included in the technical idea of this invention.

By adopting the above configuration, the present invention provides an integrating sphere in which the optical measurement error is reduced.

Claims (19)

delete delete delete delete delete delete delete delete In the integrating sphere for measuring the optical characteristics of the light source,
An integrating sphere body having a hollow portion and a light receiving hole connected to the hollow portion; And
A diffusion plate provided in the light receiving hole and diffusing the light flowing into the hollow part from the light receiving hole to uniform the light intensity;
The diffusion plate is made of a light transmissive substrate and a light diffusion layer formed on the light transmissive substrate,
The light transmitting substrate is a glass substrate, and the light diffusion layer is an integrating sphere, characterized in that the resin layer containing organic or inorganic diffusion particles. In the integrating sphere for measuring the optical characteristics of the light source,
An integrating sphere body having a hollow portion and a light receiving hole connected to the hollow portion; And
A diffusion plate provided in the light receiving hole and diffusing the light flowing into the hollow part from the light receiving hole to uniform the light intensity;
The diffusion plate is made of a light transmissive substrate and a light diffusion layer formed on the light transmissive substrate,
And the light diffusing layer is a patterned convex portion or a concave portion. The integrating sphere according to claim 10, wherein the patterned convex portion is arranged with a plurality of hemispheres, semi-cylinders, prisms, or pyramidal micro-convex lenses. The integrating sphere according to claim 10, wherein the patterned concave portion is arranged with a plurality of micro concave lenses having a hemisphere, a semi-cylindrical shape, a prisms, or a pyramid shape. In the integrating sphere for measuring the optical characteristics of the light source,
An integrating sphere body having a hollow portion and a light receiving hole connected to the hollow portion; And
A diffusion plate provided in the light receiving hole and diffusing the light flowing into the hollow part from the light receiving hole to uniform the light intensity;
The diffusion plate is made of a light transmissive substrate and a light diffusion layer formed on the light transmissive substrate,
An integrating sphere, wherein the light diffusing layer is formed on a plurality of layers on the light transmissive substrate. In the integrating sphere for measuring the optical characteristics of the light source,
An integrating sphere body having a hollow portion and a light receiving hole connected to the hollow portion; And
A diffusion plate provided in the light receiving hole and diffusing the light flowing into the hollow part from the light receiving hole to uniform the light intensity;
The diffusion plate is a light-transmissive substrate comprising a diffusion particle made of a material containing at least one of urethane resin, acrylic resin, epoxy resin, olefin resin, polyester resin, alumina, glass, silica. Integrating sphere. 15. The integrating sphere of claim 14, wherein the light transmissive substrate is a resin substrate. In the integrating sphere for measuring the optical characteristics of the light source,
An integrating sphere body having a hollow portion and a light receiving hole connected to the hollow portion; And
A diffusion plate provided in the light receiving hole and diffusing the light flowing into the hollow part from the light receiving hole to uniform the light intensity;
The diffusion plate is a fly eye lens (fly eye lens) or a prism sheet (prism sheet) characterized in that the integrating sphere. delete In the integrating sphere for measuring the optical characteristics of the light source,
An integrating sphere body having a hollow portion and a light receiving hole connected to the hollow portion; And
A diffusion plate provided in the light receiving hole and diffusing the light flowing into the hollow part from the light receiving hole to uniform the light intensity;
The diffusion plate is magnesium fluoride (MgF ₂ ), calcium fluoride (CaF ₂ ), synthetic quartz glass (fused silica) glass, borosilicate crown (BK7) glass, crystal quartz, polymethyl methacrylate (PMMA), sapphire Integrating sphere, characterized in that made of any one or more materials. delete

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