Standard reflection plate unit

Abstract

This standard reflection plate unit (1) is provided with: a standard reflection plate (20); a unit main body (10) that holds the standard reflection plate (20); and a transmissive protection member (12) that is provided so as to face the standard reflection plate (20) on one side in the thickness direction of the standard reflection plate (20) in order to protect the standard reflection plate (20), and constitutes a part of the unit main body (10). A first space (41) is formed between the standard reflection plate (20) and the transmissive protection member (12), and a second space (42) is formed between the standard reflection plate (20) and the opposing surface of the unit main body (1) on the other side in the thickness direction of the standard reflection plate (20).

Description

Standard Reflector Unit

[0001] The present invention relates to a standard reflector unit used for calibrating optical characteristic measuring devices and the like.

[0002] When measuring an object (sample) using an optical property measuring device, it is common to calibrate the sample's measurement data to calculate accurate optical property values ​​(see, for example, Patent Document 1). This calibration is performed using a standard reflector provided with reflectance data conforming to international standards. Specifically, the reflectance of the standard reflector is measured using the optical property measuring device used to measure the sample, and this measurement value is used to calibrate the sample's measurement data. Therefore, it is desirable for the standard reflector to be made of a long-term stable material whose reflectance does not fluctuate in response to environmental loads such as temperature, humidity, and ultraviolet rays. A typical example of this is lead-containing optical glass, which has traditionally been used as a standard reflector.

[0003] Japanese Patent Application Laid-Open No. 2002-243550

[0004] However, there is a problem that lead-containing optical glass will be subject to environmental regulations in the future. For this reason, there is a demand for replacement with standard reflectors made of materials that meet the same requirements as conventional ones. For example, in the case of standard reflectors used for white calibration, in order to achieve a stable white color, environmental regulations can be avoided by replacing the material of the standard reflector with barium sulfate, PTFE, etc.

[0005] On the other hand, the drawbacks of replacing these materials include the fact that the surface of the material is easily scratched and stained, making them difficult to remove. Furthermore, resin materials are susceptible to environmental impacts such as temperature, humidity, and ultraviolet rays. Furthermore, they are prone to deformation due to external forces, making it difficult to meet the same requirements as conventional materials in terms of long-term reflectivity stability.

[0006] The object of the present invention is to provide a standard reflector unit in which the reflectance of the standard reflector is stable over the long term, even when a material that is easily affected by environmental loads and external forces is used as the material for the standard reflector.

[0007] The above object is achieved by the following means: (1) A standard reflector unit comprising: a standard reflector; a unit body for holding the standard reflector; and a translucent protective member provided on one side of the standard reflector in the thickness direction opposite the standard reflector and constituting a part of the unit body, wherein a first space is formed between the standard reflector and the translucent protective member, and a second space is formed on the other side of the standard reflector in the thickness direction between the standard reflector and the opposing surface of the unit body. (2) The standard reflector unit according to the preceding paragraph 1, wherein a first spacer is provided between the standard reflector and the translucent protective member, and a second spacer is provided between the standard reflector and the opposing surface of the unit body. (3) The standard reflector unit according to the preceding paragraph 2, wherein the first spacer is made of metal and the second spacer is made of an elastic member. (4) The standard reflector unit according to any one of the preceding paragraphs 1 to 3, wherein the volume of the first space is equal to the volume of the second space. (5) The standard reflector unit according to any one of the preceding paragraphs 1 to 3, wherein the first space and the second space are connected to each other. (6) The standard reflector unit according to any one of the preceding paragraphs 1 to 3, wherein the inside of the unit body is sealed. (7) The standard reflector unit according to any one of the preceding paragraphs 1 to 3, wherein the transparent protective member is made of glass. (8) The standard reflector unit according to any one of the preceding paragraphs 1 to 3, wherein the standard reflector is made of a white material. (9) The standard reflector unit according to the preceding paragraph 8, wherein the standard reflector is made of PTFE. (10) The standard reflector unit according to the preceding paragraph 8, wherein the spectral reflectance of the standard reflector is 80% or more in the visible light range.

[0008] In the standard reflector unit according to the present invention, a first space is formed between the standard reflector and the transmissive protective member on one side of the standard reflector in the thickness direction. Furthermore, a second space is formed between the standard reflector and the opposing surface of the unit body on the other side of the standard reflector in the thickness direction. This prevents deformation of the standard reflector, such as bending or curvature due to changes in environmental temperature, as occurs when a different member is in contact with the standard reflector. Furthermore, because the first space is provided on the transmissive protective member side, the occurrence of interference fringes is suppressed, and the spectral reflectance is stabilized.

[0009] Furthermore, since the surface of the standard reflector is protected by a transparent protective member, the transparent protective member prevents the surface of the standard reflector from coming into contact with the fingertips of the measurer or external members, etc. This prevents the standard reflector from being deformed or its surface from being scratched or soiled by external forces acting on it.

[0010] Furthermore, since the first space is formed between the standard reflector and the transmissive protective member, the occurrence of interference fringes can be suppressed.

[0011] As a result, it is possible to provide a standard reflector unit in which the reflectance of the standard reflector is stable over the long term.

[0012] Fig. 1A is a partially cutaway perspective view of a standard reflector unit 1 according to one embodiment of the present invention, Fig. 1B is a plan view of the standard reflector unit 1, and Fig. 1C is a cross-sectional view taken along line IC-IC in Fig. 1B. Fig. 2A is a plan view of a standard reflector unit according to another embodiment of the present invention, and Fig. 2B is a cross-sectional view of the standard reflector unit 1 of Fig. 2A taken along line IIB-IIB in the diameter direction. Fig. 2B is a cross-sectional view of a standard reflector unit 1 according to yet another embodiment of the present invention taken along a line in the diameter direction. Fig. 2C is a cross-sectional view of a standard reflector unit 1 according to yet another embodiment of the present invention taken along a line in the diameter direction.

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] FIG. 1A is a perspective view showing a standard reflector unit 1 according to one embodiment of the present invention, with a portion cut away, FIG. 1B is a plan view of the standard reflector unit 1, and FIG. 1C is a cross-sectional view taken along line IC-IC in FIG. 1B.

[0015] As shown in these figures, the standard reflector unit 1 comprises a lower holder 11 made of, for example, resin and having an open top, and a transparent protective member 12 that closes the upper opening of the lower holder 11, and the unit main body 10 is formed by the lower holder 11 and the transparent protective member 12.

[0016] The lower holder 11 has a circular bottom wall 11a and a short cylindrical peripheral wall 11b integrally formed on the outer periphery thereof. The permeable protective member 12 is a circular plate-like member that is disposed at the upper end of the lower holder 11 and has its peripheral edge integrally joined to the lower holder 11.

[0017] The circular standard reflector 20 is held in the space within the unit body 10 via an annular first spacer 31 arranged on one side (upper side) in the thickness direction of the standard reflector 20 and an annular second spacer 32 arranged on the other side (lower side) in the thickness direction of the standard reflector 20. The outer diameters of the first and second spacers 31, 32 are both set to be approximately the same as or slightly smaller than the inner diameter of the peripheral wall portion 11b of the lower holder 11.

[0018] The lower surface of the lower second spacer 32 is supported by the upper surface of the bottom wall 11a of the lower holder 11, and the peripheral edge of the lower surface of the standard reflector 20 is supported by the upper surface of the second spacer 32. The lower surface of the upper first spacer 31 contacts the peripheral edge of the upper surface of the standard reflector 20, and the upper surface of the first spacer 31 contacts the lower surface of the transmissive protective member 12. Therefore, while being supported by the first and second spacers 31, 32, the standard reflector 20 is arranged parallel to the bottom wall 11a of the lower holder 11 and the standard reflector 20 at a central position in the height direction of the internal space of the unit main body 10. The outer diameter of the standard reflector 20 is set smaller than the inner diameter of the peripheral wall 11b of the lower holder 11, and a gap is generated between the outer peripheral surface of the standard reflector 20 and the inner peripheral surface of the peripheral wall 11b of the lower holder 11.

[0019] Due to the presence of the first spacer 31, a first space 41 having a thickness corresponding to the thickness of the first spacer 31 is formed between the standard reflector 20 and the transmissive protective member 12. On the other hand, due to the presence of the second spacer 32, a second space 42 having a thickness corresponding to the thickness of the second spacer 32 is formed between the standard reflector 20 and the upper surface of the bottom wall portion 11a of the lower holder 11 (corresponding to the opposing surface of the unit body).

[0020] The first spacer 31 is made of metal, and the second spacer 32 is made of an elastic material such as rubber or resin. The upper spacer 31 is made of metal in order to minimize thickness variations and maintain a constant distance between the standard reflector 20 and the transmissive protective member 12 with high precision. The lower spacer 32 is made of an elastic material in order to absorb dimensional variations in the bottom wall portion 11a of the lower holder 11 with the elastic material. In this embodiment, the thicknesses, widths, etc. of the first spacer 31 and the second spacer 32 are set so that the volumes of the first space 41 and the second space 42 are equal.

[0021] As described above, the first space 41 and the second space 42 are respectively formed by the first spacer 31 and the second spacer 32, so that the first space 41 and the second space 42 can be formed without joining the respective components.

[0022] The standard reflector 20 is used to calibrate an optical property measuring device. For this purpose, the standard reflector 20 is required to have a reflection angle characteristic close to that of a perfect diffuse reflecting surface, and a high stability in its spectral reflectance. However, the reflection characteristics of the standard reflector 20 are limited to the measurement wavelength range of the optical property measuring device, and characteristics outside the measurement wavelength range are not considered.

[0023] When the standard reflector 20 is used for white calibration, for example, materials for the standard reflector 20 that provide a stable white color include barium sulfate, titanium oxide, PTFE (polytetrafluoroethylene), ceramic, and silicone rubber. PTFE is particularly desirable because it has excellent environmental stability and can achieve high reflectance across the entire wavelength range of visible light. The spectral reflectance of the white standard reflector 20 is preferably 80% or higher in the visible light range (400 to 700 nm). The color of the standard reflector 20 is not limited to white; the color of the standard reflector 20 can be selected according to the color to be calibrated.

[0024] The transparent protective member 12 is made of, but not limited to, transparent glass, transparent resin, etc. Glass is particularly desirable because it is inexpensive, readily available, and hard, so it is resistant to scratches even when used repeatedly.

[0025] The transparent protective member 12 is disposed in front of the standard reflector 20 to protect the standard reflector 20. Specifically, if the standard reflector 20 made of a material such as PTFE is used alone as a calibration reflector, there is a problem that the surface is prone to scratches and dirt, which are difficult to remove. Furthermore, if the standard reflector 20 is directly exposed to the atmosphere, it is susceptible to the effects of temperature and humidity. Therefore, covering the front of the standard reflector 20 with the transparent protective member 12 prevents the occurrence of scratches and dirt on the surface. Furthermore, since the transparent protective member 12 is integrally joined to the lower holder 11, the interior of the unit body 10, which is composed of the lower holder 11 and the transparent protective member 12, is sealed. This prevents the standard reflector 20 from being directly exposed to the atmosphere, further reducing the effects of temperature and humidity.

[0026] The transmission characteristics of the transparent protective member 12 are limited to the measurement wavelength range of the optical characteristic measuring device, and it is sufficient that the transmission characteristics are maintained within the measurement wavelength range, and the characteristics outside the measurement wavelength range are not important.

[0027] If the standard reflector 20 and the transmissive protective member 12 are both flat and smooth, placing them one on top of the other will cause interference fringes due to the slight gap between them, resulting in a change in spectral reflectance. On the other hand, if the standard reflector 20 and the transmissive protective member 12 are placed apart, changing the distance between them will change the amount of reflected light, resulting in a change in spectral reflectance. Therefore, the distance between the standard reflector 20 and the transmissive protective member 12 must be kept constant.

[0028] Therefore, in this embodiment, the distance between the standard reflector 20 and the transmissive protective member 12 is maintained constant and stable by interposing the first spacer 31 between them. In particular, as described above, by making the first spacer 31 out of metal, which has little change in thickness, the distance between the standard reflector 20 and the transmissive protective member 12 can be further stabilized.

[0029] By forming the second spacer 32 from an elastic material, as described above, dimensional variations in the bottom wall portion 11a of the lower holder 11 can be absorbed, and the following effect is also achieved. That is, when a relatively soft material such as resin or rubber is used for the standard reflector 20, these materials deform (bend) due to temperature, external force, etc. Therefore, it becomes difficult to maintain a constant distance between the standard reflector 20 and the transmissive protective member 12 over the entire surface of the standard reflector 20. Therefore, in this embodiment, as described above, the second spacer 32 made of an elastic material presses the standard reflector 20 toward the transmissive protective member 12 to float it, so that the distance between the standard reflector 20 and the transmissive protective member 12 does not fluctuate due to impact from a drop, etc.

[0030] Furthermore, the air layers in the first space 41 and the second space 42, which sandwich the standard reflector 20 and are necessary for floating the standard reflector 20, expand due to changes in the environmental temperature. If there is a difference in volume between the first space and the second space, a pressure difference will occur in the air layers in both spaces, which may cause deformation (bending) of the standard reflector 20. For this reason, as described above, in this embodiment, the volumes of the first space 41 and the second space 42 are set to be equal, preventing a pressure difference from occurring in the air layers in both spaces.

[0031] 1A to 1C, a first space 41 is formed between the standard reflector 20 and the transmissive protective member 15 on one side in the thickness direction of the standard reflector 20. Furthermore, a second space 42 is formed between the standard reflector 20 and the opposing surface of the unit body 1 on the other side in the thickness direction of the standard reflector 20. This prevents deformation of the standard reflector 20, such as bending or curvature due to changes in environmental temperature, as occurs when a different member is in contact with the standard reflector 20. Furthermore, because the first space is provided on the transmissive protective member 12 side, the occurrence of interference fringes is suppressed and the spectral reflectance is stabilized.

[0032] Furthermore, because the standard reflector 20 is protected by the transparent protective member 12, the surface of the standard reflector 20 is prevented from coming into contact with the fingertips of the measurer or external members by the transparent protective member 12. This prevents the standard reflector from being deformed or its surface from being scratched or soiled due to the application of external force to the standard reflector.

[0033] Furthermore, since the first space 41 is formed between the standard reflector 20 and the transmissive protective member 12, the occurrence of interference fringes can be suppressed.

[0034] As a result, it is possible to provide a standard reflector unit 1 in which the reflectance of the standard reflector 20 is stable over the long term.

[0035] Next, a standard reflector unit 1 according to another embodiment of the present invention will be described with reference to Figures 2A and 2B. Figure 2A is a plan view of the standard reflector unit 1. Figure 2B is a cross-sectional view of the standard reflector unit 1 in Figure 2A taken along line IIB-IIB in the diameter direction.

[0036] In this embodiment, a notch 31a is formed in a portion of the circumference of the first spacer 31 across the entire width. A notch 32a is also formed in a portion of the circumference of the second spacer 32 across the entire width. These two notches 31a, 32a allow the first space 41 and the second space 42 to communicate with each other via a gap between the outer circumferential surface of the standard reflector 20 and the inner circumferential surface of the lower holder 11. In other words, an air flow path is formed connecting the first space 41 and the second space 42. The thickness (volume) of the second space 42 is set to be larger than the thickness (volume) of the first space 41.

[0037] As described above, since the first space 41 and the second space 42 are in communication with each other, even if there is a difference in volume between the first space 41 and the second space 42, the pressure difference between the air layer in the first space 41 and the air layer in the second space 42 is reduced. This makes it possible to prevent deformation of the standard reflector 20 due to the pressure difference. Moreover, since it is not necessary to set the volumes of the first space 41 and the second space 42 to be the same, the degree of freedom in designing the standard reflector unit 1 is increased.

[0038] Next, a standard reflector unit 1 according to still another embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view of the standard reflector unit 1 taken along a line in the diameter direction.

[0039] In this embodiment, instead of the second spacer 32, an annular step 13 is formed integrally with the lower holder 11 along the circular inner circumferential corner of the lower holder 11. This step 13 has an annular horizontal surface 13a and an annular vertical surface 13b, and the lower peripheral edge of the standard reflector 20 abuts and is supported on the annular horizontal surface 13a. The presence of this step 13 separates the standard reflector 20 from the bottom wall 11a of the lower holder 11, and a second space 42 is formed between the bottom wall 11a and the standard reflector 20.

[0040] The configurations of the standard reflector 20, the first spacer 31, and the transparent protective member 12 are the same as those of the standard reflector unit 1 shown in FIGS. 1A to 1C.

[0041] 3, it is also desirable to set the volumes of the first space 41 and the second space 42 to be the same. Alternatively, a notch may be provided in a portion of the circumferential direction of the first spacer 31, and a notch may be formed in the step portion 13 of the lower holder 11, to allow the first space 41 and the second space 42 to communicate with each other.

[0042] In addition, instead of the first spacer 31, a ring-shaped downward convex portion may be formed integrally with the transparent protective member 12 on the peripheral portion of the lower surface of the transparent protective member 12, and the first space 41 may be formed between the transparent protective member 12 and the standard reflector 20 by bringing this convex portion into contact with the standard reflector 20.

[0043] Next, a standard reflector unit 1 according to still another embodiment of the present invention will be described with reference to Figures 4A and 4B. Figure 4A is a plan view of the standard reflector unit, and Figure 4B is a cross-sectional view of the standard reflector unit 1 of Figure 4A taken along line IVB-IVB in the diameter direction.

[0044] In this embodiment, the unit body 10 is composed of an upper holder 14 in the shape of a short cylinder with a lid and an open bottom surface, and a bottom plate 15 that is joined to the peripheral edge of the bottom surface of the upper holder 14 and closes the bottom opening of the upper holder 14. The top plate portion of the upper holder 14 is the transmissive protective member 12, and the upper holder 14 is integrally formed from the same material as the transmissive protective member 12. Therefore, in this embodiment as well, the transmissive protective member 12 is provided above the standard reflector 20 so as to face it with the first spacer 31 interposed therebetween.

[0045] The configurations of the standard reflector 20 and the first and second spacers 31 and 32 other than the unit body 10 are the same as those of the embodiment shown in FIGS. 1A to 1C.

[0046] 4, it is also desirable to set the volumes of the first space 41 and the second space 42 to be the same. Also, a notch may be provided in a part of the circumferential direction of the first and second spacers 31, 32 to allow the first space 41 and the second space 42 to communicate with each other.

[0047] The standard reflector unit 1 according to the embodiment of the present invention is used for calibrating an optical characteristic measuring device. The optical characteristic measuring device has a measurement aperture, an illumination unit that illuminates the measurement aperture surface, and a light receiving unit that receives reflected light from the measurement aperture surface.

[0048] When calibrating the optical property measuring device, the standard reflector unit 1 is illuminated by the illumination unit of the optical property measuring device with the measurement aperture surface in contact with the surface of the transparent protective member 12 of the standard reflector unit 1. The illumination light passes through the transparent protective member 12 and is reflected by the standard reflector 20. This reflected light is received by a sensor installed in the light receiving unit of the optical property measuring device, and a measurement value corresponding to the amount of received light is output from the optical property measuring device. A calibration coefficient is calculated from this measurement value and the spectral reflectance of the standard reflector unit 1, completing the calibration.

[0049] This application claims priority from Japanese Patent Application No. 2024-083544, filed on May 22, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0050] The present invention can be used as a standard reflector unit used for calibrating optical property measuring devices and the like.

[0051] REFERENCE SIGNS LIST 1 Standard reflector unit 10 Unit body 11 Lower holder 11a Bottom wall 11b Peripheral wall 12 Transmissive protective member 13 Step 13a Horizontal surface 13b Vertical surface 14 Upper holder 15 Bottom plate 20 Standard reflector 31 First spacer 31a Cutout 32 Second spacer 32a Cutout 41 First space 42 Second space

Claims

1. A standard reflector unit comprising: a standard reflector; a unit body that holds the standard reflector; and a transparent protective member that is arranged opposite the standard reflector on one side of the standard reflector in the thickness direction and that constitutes part of the unit body, wherein a first space is formed between the standard reflector and the transparent protective member, and a second space is formed between the standard reflector and the opposing surface of the unit body on the other side of the standard reflector in the thickness direction.

2. A standard reflector unit as described in claim 1, wherein a first spacer is installed between the standard reflector and the transparent protective member, and a second spacer is installed between the standard reflector and the opposing surface of the unit body.

3. The standard reflector unit according to claim 2, wherein the first spacer is made of metal and the second spacer is made of an elastic material.

4. A standard reflector unit according to any one of claims 1 to 3, wherein the volume of the first space is equal to the volume of the second space.

5. A standard reflector unit according to any one of claims 1 to 3, wherein the first space and the second space are in communication with each other.

6. A standard reflector unit according to any one of claims 1 to 3, wherein the inside of the unit body is sealed.

7. A standard reflector unit according to any one of claims 1 to 3, wherein the transparent protective member is made of glass.

8. A standard reflector unit according to any one of claims 1 to 3, wherein the standard reflector is made of a white material.

9. The standard reflector unit according to claim 8, wherein the standard reflector is made of PTFE.

10. A standard reflector unit according to claim 8, wherein the spectral reflectance of said standard reflector is 80% or more in the visible light range.

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