CN-115727949-B - Integrating sphere

CN115727949BCN 115727949 BCN115727949 BCN 115727949BCN-115727949-B

Abstract

The invention provides an integrating sphere, which can inhibit the fluctuation of the efficiency of the integrating sphere by inhibiting the moisture absorption of the integrating sphere, thereby improving the precision of optical measurement using the integrating sphere. The integrating sphere (10) comprises a hollow member (1), and a diffusing coating film (4) which is provided on the inner surface of the hollow member (1) and which diffuses light from a light source into diffused light by scattering and reflecting the light in the hollow member (1), wherein the diffusing coating film (4) is covered with a hydrophobic coating film (5).

Inventors

NISHIDA KAZUFUMI
HORIKOSHI KUMIKO
YUAN REN

Assignees

横河电机株式会社

Dates

Publication Date: 20260512
Application Date: 20220825
Priority Date: 20210830

Claims (4)

1. An integrating sphere comprising a hollow member, a diffusive coating film provided on an inner surface of the hollow member and causing light from a light source to scatter and reflect inside the hollow member as diffused light, characterized in that, A hydrophobic coating film is coated on the diffusion coating film, The diffusion coating contains barium sulfate powder and polyvinyl alcohol binder, The hydrophobic coating film contains a powder of a hydrophobic resin and a binder of the hydrophobic resin, The powder of the hydrophobic resin is transparent at the wavelength of the light, The binder of the hydrophobic resin is transparent at the wavelength of the light.
2. The integrating sphere of claim 1, wherein said powder of hydrophobic resin has a particle size larger than a wavelength of said light.
3. The integrating sphere according to claim 1 or 2, wherein the binder of the hydrophobic resin has a refractive index different from that of the powder by 0.02 or more.
4. The integrating sphere according to claim 1 or 2, wherein the hydrophobic resin comprises a fluororesin, a silicone resin, polypropylene, polyethylene or polyethylene terephthalate.

Description

Integrating sphere Cross reference to related applications The present application claims priority from japanese patent application No. 2021-140491 filed in japan at 8-30 of 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field The invention relates to an integrating sphere. Background The integrating sphere is an optical member for diffusing and homogenizing light from the light source. For example, patent document 1 discloses a total luminous flux measuring device including an integrating sphere. Here, in measuring the total light amount of the light source having directivity, the measurement value changes according to the measurement direction of the light amount, and therefore, it is necessary to repeatedly measure the light amount in all directions. Even if the light from the light source is a light source having directivity such as an LED (LIGHT EMITTING Diode light-emitting Diode), the light is repeatedly diffused in the integrating sphere. Thus, the brightness in the integrating sphere is uniform. Therefore, the luminance in the integrating sphere is measured only once, and a measurement value proportional to the total amount of light emitted from the light source can be obtained. But the light from the light source is repeatedly scattered and reflected within the integrating sphere to become homogeneous and a portion thereof reaches the detector. Therefore, the measured value is weakened based on the reflectance in the integrating sphere. The ratio of the light that can be used among the light incident on the integrating sphere is called the efficiency of the integrating sphere. When an integrating sphere with unknown efficiency is used, the total luminous flux of the measurement object is measured by measuring a correction light source with a known total luminous flux and measuring the relative light quantity with respect to the correction light source. If the efficiency of the integrating sphere changes during a series of measurements using the integrating sphere, measurement errors occur, and thus it is important to prevent the efficiency of the integrating sphere from varying. Prior art literature Patent document 1 Japanese patent laid-open publication No. Hei 07-146175 The conventional integrating sphere has a problem in that its efficiency varies depending on the dry state of the integrating sphere. Disclosure of Invention The purpose of the present invention is to improve the accuracy of optical measurement using an integrating sphere by suppressing the moisture absorption of the integrating sphere and thereby suppressing the fluctuation of the efficiency of the integrating sphere. An integrating sphere according to some embodiments includes a hollow member, a diffusive coating film provided on an inner surface of the hollow member, and causing light from a light source to scatter and reflect inside the hollow member as diffused light, and in the integrating sphere, a hydrophobic coating film is coated on the diffusive coating film. This suppresses absorption of moisture from the surrounding humidity by the diffusion coating film. As a result, the decrease in reflectance of the diffusion coating film is suppressed, and the fluctuation in efficiency of the integrating sphere due to the ambient humidity is suppressed. In one embodiment, the hydrophobic coating film contains a single hydrophobic resin. This suppresses absorption of moisture from the surrounding humidity by the diffusion coating film. As a result, the decrease in reflectance of the diffusion coating film is suppressed, and the fluctuation in efficiency of the integrating sphere due to the ambient humidity is suppressed. In general, the diffusion coating film is formed by fixing barium sulfate powder with a gap therebetween, and causes light reflection at the interface between the powder and air to cause diffusivity. In the case of applying a hydrophobic coating film composed of only a single hydrophobic resin, the hydrophobic resin penetrates between powders of barium sulfate to reduce the reflectance of the interface with barium sulfate, and therefore the efficiency of the integrating sphere is lowered. The integrating sphere of the present invention has lower efficiency than an integrating sphere without a hydrophobic coating film, but suppresses variation. In one embodiment, the hydrophobic coating film contains a powder of a hydrophobic resin and a binder of the hydrophobic resin. This causes light reflection also at the interface between the powder of the hydrophobic resin and the hydrophobic resin binder, and the hydrophobic coating film has a function of diffusing light, so that the efficiency of the integrating sphere is improved and variation in the efficiency of the integrating sphere is suppressed, as compared with the case where a hydrophobic coating film composed of only a single hydrophobic resin is applied. In one embodiment, the powder of the hydrophobic resin is trans