JP2018036056A - Light power meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain reduction in manufacturing costs and miniaturization of a device, and sufficiently alleviate incident position dependency of measurement object light upon the device.SOLUTION: A light power meter comprises: an aperture 11 that has an incident hole 11a allowing measurement object light L to pass through, and defines an incidence allowable range for the light L; a transmission diffusion plate 21 that is arranged allowing the light L passing through the incident hole 11a to transmit, and diffuses the light L; and a diffusion reflection unit 31 that is formed into a cylinder, has the aperture 11 and the transmission diffusion plate 21 disposed on one end part side, and makes the light L transmitting the transmission diffusion plate 21 diffused/reflected upon an inner face 31a. A part of the light L diffused in the diffusion reflection unit 31 is configured to be received by a photoelectric conversion unit, and the diffusion reflection plate 21 is configured in such a way that a concave part 22 is formed in one face of an aperture 11 side, and a part of the light L to be reflected upon a bottom face 22a of the concave part 22 can be incident upon the transmission diffusion plate 21 from the inner lateral face 22b, and has a thin thickness part 23 provided in an outer edge part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical power meter configured to be able to measure a predetermined optical parameter of a measurement target light based on a signal level of a detection signal output from a photoelectric conversion unit according to the amount of light of the measurement target light. It is about.

  As this type of optical power meter, the following patent document discloses an invention of an optical power measuring device configured to be able to measure the power of light emitted from a light source such as a laser or an LED (optical radiation power).

  In this optical power measuring device, an aperture provided with an incident hole through which measurement target light can pass and a transmission diffusion plate for diffusing the measurement target light that has passed through the incident hole are disposed on one end side of the casing. In addition, a silicon photodiode (hereinafter also referred to as “photoelectric conversion unit”) in which a glass filter is integrally disposed on the light receiving surface is disposed in the casing. In this optical power measuring device, the light to be measured from the light source is diffused by passing through the incident hole of the aperture and entering the transmission diffusion plate, and a part thereof passes through the glass filter and enters the photoelectric conversion unit. It has been adopted. As a result, a detection signal corresponding to the amount of measurement target light incident on the photoelectric conversion unit (the amount of light received by the photoelectric conversion unit) is output from the photoelectric conversion unit, and the power of the measurement target light is determined based on the signal level. Is calculated.

JP 63-127127 A (page 1-4, Fig. 1-4)

  However, the conventional optical power measuring instrument has the following problems to be solved. That is, the conventional optical power measuring instrument employs a configuration in which part of the measurement target light that has passed through the aperture and diffused in the transmission diffusion plate is incident on the photoelectric conversion unit in the housing. In this case, with a conventional optical power measuring instrument, when the light to be measured is light with low diffusivity such as laser light (light non-radially output from the light source), it is measured simply by transmitting through the transmission diffusion plate. The target light cannot be sufficiently diffused, and depending on the incident position of the measurement target light on the aperture (incident hole), it is difficult to suitably receive the incident measurement target light by the photoelectric conversion unit. . For this reason, in the conventional optical power measuring device, the amount of light received by the photoelectric conversion unit varies depending on the position of the light to be measured entering the aperture (incident hole) (hereinafter, the amount of light received by the light incident position of the light to be measured). (It is also called “incident position dependency”).

  Therefore, the applicant improved the above-described optical power measuring device, and provided a diffusive reflecting part that diffusely reflects (diffusely reflects) the measurement target light diffused by transmitting through the transmissive diffusing plate, in parallel with the transmissive diffusing plate. An optical power meter was prototyped. Specifically, as shown in FIG. 6, the optical power meter prototyped by the applicant includes a light receiving sensor 2x having a diffuse reflection part 31x in which a diffuse reflection coating agent is applied to the inner surface 31ax of the cylindrical body. Hereinafter, the components of the optical power meter prototyped by the applicant will be described with “x” appended to the end of the reference numerals.

  In the light receiving sensor 2x, an aperture 11x and a transmission diffusion plate 21x are disposed on one end side (left end side in the figure) of the diffuse reflection part 31x, and the other end side (illustrated on the right side in the figure) of the diffuse reflection part 31x. The photoelectric conversion unit is disposed at a portion where the measurement target light L that has passed through the incident hole 11ax of the aperture 11x and entered the transmission diffusion plate 21x is diffused in the transmission diffusion plate 21x and transmitted and diffused. The measurement target light L diffused on the plate 21x is diffusely reflected on the inner surface 31ax of the diffuse reflection part 31x, and a part thereof enters the photoelectric conversion part. Therefore, in the optical power meter (light receiving sensor 2x) prototyped by the applicant, both the transmissive diffuser 21x and the diffuse reflector 31x are compared with the conventional optical power measuring instrument that diffuses the measurement target light only by the transmissive diffuser. In FIG. 5, the measurement target light L is diffused to reduce the dependency on the incident position.

  On the other hand, this type of measuring device is desired to be sufficiently miniaturized in order to improve its storage and portability. For this reason, it is preferable that the light receiving sensor 2x be sufficiently downsized even in the optical power meter prototyped by the applicant. In this case, when the outer diameter L3bx of the diffuse reflector 31x is reduced in order to reduce the size of the light receiving sensor 2x, the inner diameter L3ax is also reduced. In addition, when the inner diameter L3ax of the diffuse reflection portion 31x is reduced, the applicant assigns the measurement target light L closer to the outer edge portion of the incident hole 11ax than when the measurement target light L is incident on the central portion of the incident hole 11ax. It was found that the incident amount of the measurement target light L to the photoelectric conversion unit tends to be smaller when the light is incident (incident position dependency different from the incident position dependency of the conventional optical power measuring device). .

  Such incident position dependency is presumed to be due to the fact that the distance between the inner surface 31ax of the diffuse reflector 31x and the incident hole 11ax of the aperture 11x is shortened by reducing the inner diameter L3ax. Specifically, when the measurement target light L incident on the outer edge portion of the incident hole 11ax and diffused in the transmission diffusion plate 21x is diffusely reflected on the inner surface 31ax of the diffusion reflection portion 31x, the transmission diffusion plate 21x side It is considered that a part of the measurement target light L reflected toward the light beam is likely to be emitted from the incident hole 11ax to the outside of the light receiving sensor 2x through the transmission diffusion plate 21x. Therefore, it has been confirmed that such an incident position dependency is reduced by sufficiently increasing the inner diameter L3ax of the diffuse reflection portion 31x and sufficiently separating the inner surface 31ax from the incident hole 11ax.

  However, if the inner diameter L3ax of the diffuse reflection portion 31x is increased in order to reduce the dependency on the incident position generated in the optical power meter (light receiving sensor 2x) prototyped by the applicant, it is only difficult to reduce the size. In addition, the manufacturing cost of the diffuse reflection part 31x (the material cost of the material for generating the cylinder and the diffuse reflection coating agent) increases, and as a result, the manufacturing cost of the light receiving sensor 2x increases. Therefore, when the inner diameter L3ax of the diffuse reflection portion 31x is increased in order to reduce the incident position dependency as described above, it is not only difficult to reduce the size of the light receiving sensor 2x, but also an optical power meter is manufactured. Costs may rise. For this reason, it is necessary to improve this point.

  The present invention has been made in view of the problems to be improved, and can reduce the manufacturing cost and the size of the apparatus, and can sufficiently reduce the dependency of the incident light on the measuring object on the incident position. The main purpose is to provide a meter.

  In order to achieve the above object, the optical power meter according to claim 1 includes a photoelectric conversion unit that outputs a detection signal corresponding to the amount of light to be measured, and a predetermined optical parameter for the light to be measured. The optical power meter is configured to be capable of measuring based on the signal level of the detection signal, and is provided with an incident hole through which the measurement target light can pass, so that the measurement target light enters the optical power meter. A permissible incident range defining portion that defines a permissible range; a transmission diffusion plate that is arranged adjacent to the permissible incident range defining portion so that the measurement target light that has passed through the incident hole can be transmitted; A diffuse reflection part that is formed in a shape and has the allowable incidence range defining part and the transmission diffusion plate disposed on one end side, and diffusely reflects the measurement target light transmitted through the transmission diffusion plate on the inner surface; A part of the measurement target light diffused in the diffuse reflection part is received by the photoelectric conversion part, and the transmission diffusion plate has a concave part on one side of the incident allowable range defining part side. A portion of the measurement target light that is formed and passes through the incident hole and is reflected at the bottom surface of the recess is configured to be incident on the transmission diffusion plate from the inner surface of the recess, and around the recess. A thin part thinner than the thickness is provided at the outer edge part.

  The optical power meter according to claim 2 further includes a photoelectric conversion unit that outputs a detection signal corresponding to the amount of received light of the measurement target light, and a predetermined optical parameter for the measurement target light is set to the detection signal. An optical power meter configured to be able to measure based on a signal level, and an incident hole through which the measurement target light can pass is provided to define an allowable range of incidence of the measurement target light on the optical power meter An incident allowable range defining portion, a transmission diffusion plate that is arranged adjacent to the incident allowable range defining portion so that the measurement target light that has passed through the incident hole can pass therethrough, and diffuses the measurement target light, and is formed in a cylindrical shape. The incident allowable range defining portion and the transmission diffusion plate are disposed on one end side, and a diffusion reflection portion for diffusing and reflecting the measurement target light transmitted through the transmission diffusion plate on the inner surface thereof. A part of the measurement object light diffused in the reflection part is configured to be received by the photoelectric conversion part, and the transmission diffusion plate has a concave part formed on one surface on the incident allowable range defining part side, and the incident light A part of the measurement target light that passes through the hole and is reflected at the bottom surface of the recess is configured to be incident on the transmission diffusion plate from the inner surface of the recess.

  The optical power meter according to claim 3 is the optical power meter according to claim 1 or 2, wherein the transmission diffusion plate is formed such that an inner diameter of the concave portion is larger than an aperture diameter of the incident hole. ing.

  Furthermore, the optical power meter according to claim 4 is the optical power meter according to any one of claims 1 to 3, further comprising a bottomed cylindrical casing, wherein a bottom plate of the casing functions as the incident allowable range defining portion. The incident hole is formed in the bottom plate, the transmission diffusion plate formed in a disc shape smaller than the inner diameter of the casing, and the cylindrical shape smaller in diameter than the inner diameter of the casing. The diffuse reflection portion is accommodated in the casing and integrated with the casing.

  The optical power meter according to claim 1, wherein the measurement target light that has passed through the incident hole of the allowable incident range defining portion is arranged adjacent to the allowable input range defining portion so as to be transmissive and diffuses the measured target light. A concave portion is formed on one surface of the range defining portion side, and a part of the measurement target light reflected on the bottom surface of the concave portion is configured to be incident on the transmissive diffusion plate from the inner side surface of the concave portion, and the outer edge portion of the transmissive diffusion plate Is provided with a thin portion thinner than the thickness around the recess.

  Therefore, according to the optical power meter of the first aspect, in the same manner as the optical power meter prototyped by the applicant, the measurement object incident from the incident hole by the amount provided with the diffuse reflection part in addition to the transmission diffusion plate. Light can be diffused sufficiently, which not only reduces the dependency of the incident light on the incident position of the light to be measured, but also makes it closer to the outer edge of the incident hole due to the presence of the concave portion provided in the transmission diffusion plate. Even if a part of the measurement target light that has entered the diffuse reflection portion when the measurement target light is incident on is reflected on the inner surface of the diffuse reflection portion and emitted to the outside from the incident hole, the concave portion passes through the incident hole. Since a part of the measurement target light reflected on the bottom surface of the light enters the transmission diffuser plate from the inner side surface of the recess and is diffused, it enters the diffuse reflection part. Enter the converter Results The amount of measured light is increased, it is possible to reduce sufficiently the incident position dependency of the measured light with respect to incident hole. As a result, the diameter of the diffuse reflector can be reduced without degrading the performance of the optical power meter, so that the optical power meter can be sufficiently reduced in size, and the manufacturing cost of the diffuse reflector can be reduced to reduce the light. The manufacturing cost of the power meter can be sufficiently reduced. Unlike designing a transmission diffuser plate that has suitable optical characteristics by changing only the depth and inner diameter of the recess in order to reduce the incidence position dependence, the outer edge is less affected by changes in dimensions. By providing the portion and arbitrarily changing its thickness, the optical characteristics of the transmission diffusion plate can be easily brought close to the ideal state.

  3. The optical power meter according to claim 2, wherein the light to be measured that has passed through the incident hole of the allowable incident range defining portion is arranged adjacent to the allowable incident range defining portion so as to be transmissive and diffuses the measured light. A concave portion is formed on one surface of the range defining portion side, and a part of the measurement target light reflected on the bottom surface of the concave portion can be incident on the transmission diffusion plate from the inner side surface of the concave portion.

  Therefore, according to the optical power meter according to claim 2, in the same manner as the optical power meter prototyped by the applicant, the measurement object incident from the incident hole by the amount provided with the diffusing reflection part in addition to the transmission diffusion plate Light can be diffused sufficiently, which not only reduces the dependency of the incident light on the incident position of the light to be measured, but also makes it closer to the outer edge of the incident hole due to the presence of the concave portion provided in the transmission diffusion plate. Even if a part of the measurement target light that has entered the diffuse reflection portion when the measurement target light is incident on is reflected on the inner surface of the diffuse reflection portion and emitted to the outside from the incident hole, the concave portion passes through the incident hole. Since a part of the measurement target light reflected on the bottom surface of the light enters the transmission diffuser plate from the inner side surface of the recess and is diffused, it enters the diffuse reflection part. Enter the converter Results The amount of measured light is increased, it is possible to reduce sufficiently the incident position dependency of the measured light with respect to incident hole. As a result, the diameter of the diffuse reflector can be reduced without degrading the performance of the optical power meter, so that the optical power meter can be sufficiently reduced in size, and the manufacturing cost of the diffuse reflector can be reduced to reduce the light. The manufacturing cost of the power meter can be sufficiently reduced.

  According to the optical power meter of the third aspect, since the transmission diffusion plate is formed so that the inner diameter of the recess is larger than the diameter of the incident hole, the measurement target light is made incident near the outer edge of the incident hole. In this case, it is possible to avoid a situation in which the amount of the measurement target light incident on the transmission diffusion plate from the inner surface increases excessively, and to appropriately reduce the dependency of the measurement target light on the incident hole.

  According to the optical power meter of claim 4, the incident hole is formed in the bottom plate so that the bottom plate in the bottomed cylindrical casing functions as the allowable incidence range defining portion, the disc-shaped transmission diffusion plate, and the cylinder The diffuse diffuser is housed in the casing and integrated with the casing, so that the transmission diffuser and diffuse reflector are covered with the casing, and the external force is directly applied to the diffuse diffuser and diffuse reflector. As a result of avoiding the situation in which the optical power is applied, the optical power meter can be suitably prevented from being damaged.

1 is a configuration diagram of an optical power meter 1. FIG. FIG. 4 is a cross-sectional view for explaining the configuration of an aperture 11 (casing 10) and a diffusion optical system 12 in the light receiving sensor 2. FIG. 6 is a cross-sectional view for explaining the reflection of the measurement target light L at the central portion of the recess 22 formed in the transmission diffusion plate 21. FIG. 6 is a cross-sectional view for explaining the reflection of the measurement target light L at the outer edge portion of the recess 22 formed in the transmission diffusion plate 21. It is sectional drawing for demonstrating the structure of the aperture 11 (casing 10) and the diffusion optical system 12A in the light reception sensor 2A. It is sectional drawing for demonstrating the structure of the aperture 11x, the permeation | transmission diffuser plate 21x, and the housing | casing 31x in the light reception sensor 2x made as an experiment by the applicant.

  Hereinafter, embodiments of an optical power meter will be described with reference to the accompanying drawings.

  An optical power meter 1 shown in FIG. 1 is an example of an “optical power meter”, and includes a light receiving sensor 2, a signal processing circuit 3, an operation unit 4, a display unit 5, a processing unit 6, and a storage unit 7, and includes laser light. The amount of radiation of the measurement target light L, the amount of light measurement, and the like (an example of “predefined optical parameters for the measurement target light”) can be measured. As shown in FIG. 2, the light receiving sensor 2 includes a casing 10, a diffusion optical system 12, and a photoelectric conversion unit 13 (see FIG. 1).

  The casing 10 is an example of a “casing” and is formed in a bottomed cylindrical shape. In this case, in the optical power meter 1 (light receiving sensor 2) of this example, the circular incident hole 11a has the bottom plate 10a so that the bottom plate 10a of the casing 10 functions as the aperture 11 which is an example of the “incident allowable range defining portion”. Is formed. In addition, the incident hole 11a has an aperture L1 that is wider than the beam diameter of the measurement target light L, and can sufficiently diffuse the measurement target light L in the diffusion optical system 12, as will be described later. It is defined to a size that restricts the incidence of the measurement target light L from a position outside the range of the incident position of the measurement target light L that allows the light receiving sensor 2 to exhibit suitable optical characteristics.

  The diffusion optical system 12 includes a transmission diffusion plate 21 and a diffusion reflection unit 31. The transmission diffusion plate 21 is an example of a “transmission diffusion plate”, and is formed in a disk shape with a milky white resin material or the like so that the measurement target light L that has passed through the incident hole 11a can be transmitted. By being accommodated in the casing 10 together with the diffuse reflection portion 31, it is disposed adjacent to the aperture 11 (the bottom plate 10 a of the casing 10).

  The transmission diffusion plate 21 is formed to have a smaller diameter than the inner diameter of the casing 10, and a concave portion 22 having a depth D2 is formed on one surface in contact with the aperture 11 (the bottom plate 10a of the casing 10), as shown in FIG. In addition, a part of the measurement target light L that passes through the incident hole 11 a and is reflected on the bottom surface 22 a of the recess 22 enters the transmission diffusion plate 21 from the inner surface 22 b of the recess 22. As shown in FIG. 2, the recess 22 is formed such that its inner diameter L2 is larger than the diameter L1 of the incident hole 11a. Thereby, in the optical power meter 1 (light receiving sensor 2) of this example, the rim portion of the incident hole 11a in the aperture 11 extends over the concave portion 22 of the transmission diffusion plate 21 over the entire circumference. . In the transmissive diffusion plate 21 of the present example, the recess 22 is formed so that the inner diameter L2 is the same from the rim to the bottom surface 22a, whereby the extended surface of the bottom surface 22a and the extended surface of the inner side surface 22b are formed. It is configured to intersect at right angles.

  Further, in this transmission diffusion plate 21, an annular thin portion 23 is provided on the outer edge portion thereof with a thickness T <b> 2 that is thinner than the thickness T <b> 1 around the recess 22 (for example, the same thickness as the depth D <b> 2 of the recess 22). . The optical functions of the concave portion 22 and the thin portion 23 will be described in detail later, but the outer edge thickness T2 can be made thinner than the depth D2 of the concave portion 22 as necessary. It can be made thicker than the depth D2.

  The diffuse reflection unit 31 is an example of a “diffuse reflection unit”, and passes through the incident hole 11a of the aperture 11 and is transmitted through the diffusion optical system 12 (diffused in the diffusion optical system 12). Is configured so that it can be diffusely reflected on the inner surface 31a. The diffuse reflection section 31 is formed in a cylindrical shape having an outer diameter L3b that is the same as the inner diameter of the casing 10, and an inner diameter L3a that is larger than the diameter L1 of the incident hole 11a and the inner diameter L2 of the recess 22. In this case, in the optical power meter 1 (light receiving sensor 2) of this example, the transmission diffuser plate 21 and the diffuse reflector 31 are accommodated in the casing 10 so as to be integrated with the casing 10, thereby the aperture 11. The (bottom plate 10a), the transmissive diffusing plate 21, and the diffusing and reflecting portion 31 are adjacently disposed along the emission direction of the measurement target light L from the light source.

  The photoelectric conversion unit 13 outputs a detection signal corresponding to the amount of received light of the measurement target light L. In this case, in the optical power meter 1 (light receiving sensor 2) of this example, as an example, a part of the measurement target light L diffused in the diffusing optical system 12 (the transmissive diffusing plate 21 and the diffusive reflecting portion 31) can be received. The photoelectric conversion unit 13 is disposed at an end (not shown) of the diffuse reflection unit 31 (the right end in FIG. 2). In the actual optical power meter 1, depending on the application, an optical filter that transmits only the measurement target light L in an arbitrary wavelength range, an optical filter having a different transmittance for each wavelength, and an optical path of the measurement target light L are provided. Various optical components such as a reflective optical system and a refractive optical system to be changed are disposed in front of the photoelectric conversion unit 13. For easy understanding of the optical power meter 1, these are illustrated and described. Omitted.

  The signal processing circuit 3 performs A / D conversion on an I / V conversion unit that performs I / V conversion on a detection signal (current signal) output from the photoelectric conversion unit 13 and an output signal (voltage signal) of the I / V conversion unit. An A / D conversion unit is provided, and a digital signal corresponding to the amount of light of the measurement target light L received by the photoelectric conversion unit 13 is output to the processing unit 6. The operation unit 4 includes various operation switches for setting measurement process conditions and instructing start / stop of the measurement process, and outputs an operation signal corresponding to the switch operation to the processing unit 6. The display unit 5 displays a measurement condition setting screen, a measurement result display screen, and the like (both not shown) according to the control of the processing unit 6.

  The processing unit 6 controls the optical power meter 1 as a whole. Specifically, the processing unit 6 controls the signal processing circuit 3 to start signal processing of the detection signal from the photoelectric conversion unit 13 when instructed to start measurement processing by operating the operation unit 4, A detection signal output from the processing circuit 3 (a digital signal having a value different depending on the amount of light L to be measured by the photoelectric conversion unit 13) is stored in the storage unit 7. Further, the processing unit 6 calculates the radiation amount, the light measurement amount, and the like of the measurement target light L based on the detection signal stored in the storage unit 7. Furthermore, the processing unit 6 generates measurement result data indicating the calculated result, stores the measurement result data in the storage unit 7, and causes the display unit 5 to display the value. The storage unit 7 stores an operation program for the processing unit 6, a detection signal output from the signal processing circuit 3, measurement result data, and the like.

  In manufacturing the optical power meter 1, first, the casing 10 and the diffusing optical system 12 (the transmissive diffusing plate 21 and the diffusing / reflecting portion 31) are respectively manufactured, and the light receiving sensor 2 is assembled. Specifically, as an example, a cylindrical aluminum lump is cut and processed into a bottom cylindrical shape, and an incident hole 11a having a diameter L1 is formed in the center portion of the bottom plate 10a. As a result, the bottom plate 10a functions as the aperture 11 and the casing 10 is completed.

  Further, as an example, the transmission diffusion plate 21 is formed by cutting a disc having the same diameter as the inner diameter of the casing 10 and having a thickness T1 (see FIG. 2). And the outer edge of the other surface is thinned over the entire circumference to form a thin portion 23 having a thickness T2. In addition, about the thin part 23, it can replace with said structure which cuts the surface on the opposite side to the formation surface of the recessed part 22, and can also form it by cutting the outer edge part in the formation surface of the recessed part 22. FIG. Further, the transmission diffusion plate 21 can be manufactured by injection molding using a mold capable of forming the concave portion 22 and the thin portion 23 instead of the above manufacturing method of cutting a disk.

  Furthermore, for the diffuse reflection part 31, as an example, a cylindrical resin sintered body having an outer diameter L3b obtained by sintering PTFE (polytetrafluoroethylene) powder is cut into a cylindrical body having an inner diameter L3a. Process. In this case, since the resin sintered body as described above is very expensive, the manufacturing cost (material cost) of the diffuse reflector 31 can be reduced by setting the outer diameter L3b to the minimum necessary size. .

  Next, the transmissive diffusion plate 21 and the diffuse reflection portion 31 are inserted in this order from the end of the casing 10 opposite to the bottom plate 10a. At this time, as shown in FIG. 2, the transmissive diffusion plate 21 is inserted so that the formation surface of the recess 22 in the transmissive diffusion plate 21 faces the bottom plate 10 a (aperture 11). As a result, the periphery of the recess 22 in the transmission diffusion plate 21 is in contact with the inner surface of the bottom plate 10 a in the casing 10, and one end portion of the diffuse reflection portion 31 is in contact with the thin portion 23 in the transmission diffusion plate 21. In this case, in the optical power meter 1 (light receiving sensor 2) of this example, the outer diameter of the transmissive diffusion plate 21 is larger than the inner diameter of the diffuse reflection portion 31 (as an example, the outer diameter of the transmissive diffusion plate 21). Is formed to have the same diameter as the outer diameter of the diffuse reflection portion 31. Therefore, by inserting the transmissive diffusion plate 21 and the diffuse reflection portion 31 into the casing 10 as described above, the transmissive diffusion plate 21 is sandwiched between the bottom plate 10 a (aperture 11) and the diffuse reflection portion 31 of the casing 10. Thus, these are integrated.

  Subsequently, as an example, the photoelectric conversion unit 13 is attached to the end of the casing 10 opposite to the bottom plate 10a. Thereby, the light receiving sensor 2 is completed. Thereafter, the manufactured light receiving sensor 2 is assembled to a main body (not shown) together with the signal processing circuit 3, the operation unit 4, the display unit 5, the processing unit 6, the storage unit 7, and the like. Instead of the manufacturing method in which the photoelectric conversion unit 13 is attached in advance to the other end portion of the casing 10, the photoelectric conversion unit 13 is attached in advance to the site where the light receiving sensor 2 is disposed in the main body, and the photoelectric conversion unit 13 is installed. A method of attaching the casing 10 and the diffusing optical system 12 to the main body so that the measurement target light L is incident on the conversion unit 13 can also be adopted. Thus, the optical power meter 1 is completed.

  When using this optical power meter 1 to measure the radiation amount, light measurement amount, etc. (hereinafter also referred to as “measurement amount”) of the measurement target light L, the light receiving sensor 2 is irradiated from the incident hole 11 a of the aperture 11. The measurement target light L is incident. At this time, the measurement target light L that has passed through the incident hole 11a is diffused when being transmitted through the transmission diffusion plate 21, and diffused and reflected by the inner surface 31a of the diffusive reflecting portion 31, so that it has passed through the incident hole 11a. Part of the measurement target light L is reliably incident on the photoelectric conversion unit 13. As a result, a detection signal having a signal level corresponding to the amount of the measurement target light L incident on the photoelectric conversion unit 13 (the amount of light received by the photoelectric conversion unit 13) is output from the photoelectric conversion unit 13.

  Further, the signal processing circuit 3 performs signal processing on the detection signal output from the photoelectric conversion unit 13, and the processing unit 6 stores the data of the detection signal after processing in the storage unit 7, and the value (signal level of the detection signal). ) To calculate the amount to be measured. Thereby, the calculated (measured) measured amount is displayed on the display unit 5 and the measurement process is completed.

  In this case, as shown in FIG. 3, when the measurement target light L is incident on the central portion of the incident hole 11a in the above measurement process, the light passes through the incident hole 11a and enters the recess 22 as indicated by an arrow A1. The measurement target light L that has entered partly reflects off the bottom surface 22a as shown by arrows A2a, A2b, etc. and is emitted from the incident hole 11a to the outside of the light receiving sensor 2, but enters the recess 22 Most of the light L enters the transmissive diffusion plate 21 from the bottom surface 22 a of the recess 22 and is diffused in the transmissive diffusion plate 21, and enters the diffusing reflection portion 31 from the surface opposite to the aperture 11 in the transmissive diffusion plate 21. Emitted.

  Further, the measurement target light L (measurement target light L diffused when transmitted through the transmission diffusion plate 21) emitted into the diffuse reflection section 31 is diffusely reflected on the inner surface 31a. Thereby, in this optical power meter 1 (light receiving sensor 2), the dependency on the incident position of the measurement target light L in the central portion of the incident hole 11a and in the vicinity thereof is sufficiently reduced, and the measurement target light that has passed through the incident hole 11a. A certain amount of measurement target light L out of L can be incident on the photoelectric conversion unit 13 (not shown).

  On the other hand, as shown in FIG. 4, when the measurement target light L is incident near the outer edge of the incident hole 11a, the measurement target light that has passed through the incident hole 11a and entered the recess 22 as indicated by an arrow B1. Most of L enters the transmission diffusion plate 21 from the bottom surface 22a of the recess 22 and is diffused in the transmission diffusion plate 21 in the same manner as when the measurement target light L is incident on the central portion of the incident hole 11a. The light is emitted from the surface of the transmissive diffusion plate 21 opposite to the aperture 11 into the diffuse reflector 31.

  However, a part of the measurement target light L that has entered the recess 22 as indicated by the arrow B1 is reflected at the bottom surface 22a as indicated by the arrows B2a, B2b, etc., and is reflected as indicated by the arrow B2a among them. Although the measurement target light L is emitted from the incident hole 11a to the outside of the light receiving sensor 2, the measurement target light L reflected as indicated by the arrow B2b or the like enters the transmission diffusion plate 21 from the inner side surface 22b of the recess 22. The light is incident and diffused in the transmissive diffusion plate 21, and is emitted into the diffuse reflection portion 31 from the surface opposite to the aperture 11 in the transmissive diffusion plate 21 together with the measurement target light L incident from the bottom surface 22 a of the recess 22.

  For this reason, when the measurement target light L is incident near the outer edge of the incident hole 11a, the measurement target light L reflected on the bottom surface 22a is reflected as when the measurement target light L is incident on the central part of the incident hole 11a. Compared to a state in which all of the light is not incident on the light receiving sensor 2, the aperture 11 in the transmissive diffusion plate 21 is equivalent to the measurement target light L incident on the transmissive diffusion plate 21 from the inner side surface 22b after being reflected on the bottom surface 22a. The amount of light emitted from the opposite surface to the diffuse reflector 31 increases.

  In this case, in the optical power meter 1 (light receiving sensor 2) of the present example, the inner diameter L3a of the diffuse reflector 31 is sufficiently reduced for the purpose of reducing the size and reducing the material cost. Therefore, if the reflection and incidence of the measurement target light L as described above in the concave portion 22 of the transmission diffusion plate 21 is not taken into consideration, the conventional optical power prototyped by the applicant is also produced in this optical power meter 1 (light receiving sensor 2). Similar to the meter (light receiving sensor 2x), when the measurement target light L is incident near the outer edge portion of the incident hole 11a due to the short distance between the inner surface 31a of the diffuse reflection part 31 and the incident hole 11a. Incident position dependency that the amount of the measurement target light L incident on the photoelectric conversion unit 13 is reduced occurs.

  However, in the optical power meter 1 (light receiving sensor 2) of the present example, as described above, when the measurement target light L is incident near the outer edge of the incident hole 11a, the bottom surface 22a of the concave portion 22 in the transmission diffusion plate 21. Part of the measurement target light L reflected in the step enters the transmission diffuser plate 21 from the inner side surface 22b, and the measurement target light enters the diffuse reflection part 31 from the transmission diffuser plate 21 by this measurement target light L. The light quantity of L increases. For this reason, even if a part of the measurement target light L diffusely reflected on the inner surface 31a of the diffuse reflector 31 is transmitted through the transmission diffusion plate 21 and emitted from the incident hole 11a to the outside of the light receiving sensor 2, the incident hole 11a. It is possible to allow the measurement target light L to be incident on the photoelectric conversion unit 13 with a sufficient amount equivalent to that when the measurement target light L is incident on the center of the photoelectric conversion unit 13. Thereby, in the optical power meter 1 (light receiving sensor 2) of this example, the dependency on the incident position of the measurement target light L with respect to the incident hole 11a is sufficiently reduced.

  In this case, when the measurement target light L is incident near the outer edge of the incident hole 11a, the amount of the measurement target light L that is reflected from the bottom surface 22a of the recess 22 and enters the transmission diffusion plate 21 from the inner side surface 22b is: It changes in accordance with the height of the inner side surface 22b, that is, the depth D2 of the recess 22. Specifically, when the depth D2 of the recess 22 is deep (when the inner side surface 22b is high), the measurement target light L reflected on the bottom surface 22a easily enters the transmission diffusion plate 21 from the inner side surface 22b. Therefore, the amount of incident light from the inner side surface 22b in the measurement target light L reflected on the bottom surface 22a increases. Further, when the depth D2 of the concave portion 22 is shallow (when the inner side surface 22b is low), the measurement target light L reflected on the bottom surface 22a is difficult to enter the transmission diffusion plate 21 from the inner side surface 22b. The amount of incident light from the inner side surface 22b in the measurement target light L reflected at 22a decreases.

  In addition, when the measurement target light L is incident near the outer edge of the incident hole 11a, the amount of the measurement target light L that is reflected from the bottom surface 22a of the recess 22 and enters the transmission diffusion plate 21 from the inner side surface 22b is as described above. In addition to the height of the inner side surface 22b, the distance between the incident position of the measurement target light L on the bottom surface 22a and the inner side surface 22b, that is, the difference between the diameter L1 of the incident hole 11a and the inner diameter L2 of the concave portion 22 It changes according to the size.

  Specifically, when the difference between the inner diameter L2 of the concave portion 22 and the diameter L1 of the incident hole 11a is small, the distance between the incident position of the measurement target light L on the bottom surface 22a and the inner side surface 22b is shortened. Since the measurement target light L reflected at 22a easily enters the transmission diffuser 21 from the inner side surface 22b, the amount of incident light from the inner side surface 22b in the measurement target light L reflected at the bottom surface 22a increases. Further, when the difference between the inner diameter L2 of the concave portion 22 and the aperture L1 of the incident hole 11a is large, the distance between the incident position of the measurement target light L on the bottom surface 22a and the inner side surface 22b is increased, so that the reflection at the bottom surface 22a. Since the measurement target light L is less likely to enter the transmission diffusion plate 21 from the inner side surface 22b, the amount of incidence from the inner side surface 22b in the measurement target light L reflected on the bottom surface 22a is reduced.

  As described above, the depth D2 and the inner diameter L2 of the concave portion 22 formed in the transmission diffusion plate 21 are set in the transmission diffusion plate 21 from the inner side surface 22b when the measurement target light L is incident near the outer edge portion of the incident hole 11a. It can be understood that it greatly affects the amount of incident measurement target light L. For this reason, at the time of designing the optical power meter 1 (light receiving sensor 2), the values of the depth D2 and the inner diameter L2 of the recess 22 are optimized so as to sufficiently reduce the incident position dependency of the measurement target light L with respect to the incident hole 11a. It is necessary to make it.

  However, with respect to the depth D2 and the inner diameter L2 of the concave portion 22, even if the dimensions are slightly changed, the incident amount of the measurement target light L from the inner side surface 22b greatly changes. Further, the depth D2 and the inner diameter L2 of the recess 22 greatly affect not only the incident amount of the measurement target light L from the inner side surface 22b but also the diffusibility of the measurement target light L in the transmission diffusion plate 21. For this reason, it is difficult to define the dimensions in consideration of only the incident amount from the inner side surface 22b.

  Therefore, in the optical power meter 1 (light receiving sensor 2) of the present example, at the design stage, as an example, first, measurement from the inner side surface 22b when the measurement target light L is incident near the outer edge of the incident hole 11a. The condition is that the incident amount of the target light L does not become less than the ideal incident amount (the incident amount at which the dependency of the measurement target light L on the incident hole 11a is substantially “0”). As described above, the depth D2 and the inner diameter L2 of the recess 22 are defined in consideration of the inherent optical characteristics (transmission diffusibility) required for the transmission diffusion plate 21. Next, by defining the depth D2 and the inner diameter L2 as described above, the incident amount of the measurement target light L from the inner side surface 22b when the measurement target light L is incident near the outer edge of the incident hole 11a is ideal. When the incident amount is different from the typical incident amount, the thickness T2 of the thin portion 23 formed on the outer edge portion of the transmission diffusion plate 21 is optimized in consideration of the difference from the ideal incident amount.

  In this case, by reducing the thickness of any part of the transmissive diffusion plate 21, the diffusibility of the measurement target light L in the thinned part changes from the non-thinned state. By appropriately changing whether the thickness is reduced, the incident amount of the measurement target light L from the inner side surface 22b when the measurement target light L is incident near the outer edge portion of the incident hole 11a may be set to an ideal state. it can.

  Further, the diffusion due to the thinning is closer to the outer edge part (the part far from the incident hole 11a) in the transmissive diffusion plate 21 than the central part (the part near the incident hole 11a) in the transmissive diffusion plate 21. It has been confirmed that the effect on sex is reduced. That is, the thickness T2 of the thin portion 23 has less influence on the incident position dependency than the depth D2 and the inner diameter L2 of the concave portion 22, and the outer edge portion that is sufficiently separated from the incident hole 11a is the thin portion 23. Thus, the influence on the original optical specification required for the transmission diffusion plate 21 is sufficiently reduced. For this reason, it is possible to change the dimension of the thickness T2 more easily than the depth D2 and the inner diameter L2. As a result, only the depth D2 and the inner diameter L2 of the recess 22 are changed to reduce the incident position dependency without disturbing the optical function (diffusion of the measurement target light L) required for the transmission diffusion plate 21. Thus, it is possible to easily design the transmissive diffusion plate 21 having a desired optical function and capable of sufficiently reducing the incident position dependency.

  On the other hand, in this type of measuring device, an impact or vibration may be applied to the measuring device during carrying or use. In this case, the diffuse reflection part 31 made of a resin sintered body has a slightly lower physical strength than a cylindrical body injection-molded with a general resin material. Therefore, when the vibration or impact as described above is directly applied to the diffuse reflector 31, the diffuse reflector 31 may be deformed or damaged. However, in the optical power meter 1 (light receiving sensor 2) of this example, the diffuse reflection part 31 is housed in the casing 10 and integrated with the casing 10 together with the transmissive diffusion plate 21, so Thus, a situation in which an impact or vibration is directly applied is preferably avoided.

  As described above, in the optical power meter 1, the measurement target light L that has passed through the incident hole 11 a of the aperture 11 is arranged adjacent to the aperture 11 so as to be transmissive, and diffuses the measurement target light L to the aperture 11 side. The concave portion 22 is formed on one surface, and a part of the measurement target light L reflected from the bottom surface 22a of the concave portion 22 is configured to be incident on the transmissive diffusion plate 21 from the inner side surface 22b of the concave portion 22, and the transmissive diffusion plate A thin portion 23 having a thickness T2 thinner than a thickness T1 around the recess 22 is provided on the outer edge portion 21.

  Therefore, according to this optical power meter 1, in the same manner as the optical power meter prototyped by the applicant, the measurement object incident from the incident hole 11 a by the amount provided with the diffusing reflection portion 31 in addition to the transmission diffusion plate 21. The light L can be sufficiently diffused, whereby not only the incident position dependency of the measurement target light L on the incident hole 11a can be reduced, but also the incident due to the presence of the recess 22 provided in the transmission diffusion plate 21. When the measurement target light L is incident near the outer edge of the hole 11a, a part of the measurement target light L that has entered the diffuse reflection part 31 is reflected by the inner surface 31a of the diffuse reflection part 31 to the outside from the incident hole 11a. Even if the light is emitted, a part of the measurement target light L that has passed through the incident hole 11a and reflected on the bottom surface 22a of the concave portion 22 enters the transmission diffusion plate 21 from the inner side surface 22b of the concave portion 22 and spreads. After that, the amount of the measurement target light L that finally enters the photoelectric conversion unit 13 is increased by the amount of the measurement target light L, so that the measurement target light with respect to the incident hole 11a is increased. The dependence of L on the incident position can be sufficiently reduced. Thereby, since the diameter of the diffuse reflection part 31 can be reduced without reducing the performance of the optical power meter 1, the optical power meter 1 can be sufficiently reduced in size, and the manufacturing cost of the diffuse reflection part 31 can be reduced. The manufacturing cost of the optical power meter 1 can be sufficiently reduced. In addition, in order to reduce the dependency on the incident position, unlike the case where the transmission diffuser plate 21 having suitable optical characteristics is designed by changing only the depth D2 and the inner diameter L2 of the recess 22, there is an influence due to a change in dimensions. By providing the thin portion 23 on the small outer edge portion and arbitrarily changing the thickness T2, the optical characteristics of the transmission diffusion plate 21 can be easily brought close to the ideal state.

  Further, according to the optical power meter 1, the transmission diffuser plate 21 is formed so that the inner diameter L2 of the recess 22 is larger than the diameter L1 of the incident hole 11a, so that the measurement is closer to the outer edge of the incident hole 11a. Avoiding an excessive increase in the amount of measurement target light L that enters the transmission diffuser 21 from the inner side surface 22b when the target light L is incident, and dependency of the measurement target light L on the incident hole 11a. Can be suitably reduced.

  Further, according to the optical power meter 1, the bottom plate 10a in the bottomed cylindrical casing 10 “is formed with the incident hole 11a in the bottom plate 10a so as to function as an incident allowable range defining portion (aperture 11), The transmissive diffuser plate 21 and the cylindrical diffuse reflector 31 are accommodated in the casing 10 and integrated with the casing 10, so that the transmissive diffuser plate 21 and the diffuse reflector 31 are covered with the casing 10. As a result of avoiding a situation in which an external force is directly applied to the transmissive diffusion plate 21 and the diffusive reflecting portion 31, damage to the optical power meter 1 can be preferably avoided.

  The configuration of the “optical power meter” is not limited to the configuration of the optical power meter 1 described above. For example, the configuration of the light receiving sensor 2 including the diffusing optical system 12 having the transmissive diffusion plate 21 provided with the thin portion 23 at the outer edge portion has been described as an example. However, the depth D2 and the inner diameter L2 of the concave portion 22 are optimized. If the incident position dependency is sufficiently reduced by the above, a diffusing optical system 12A having a transmissive diffusion plate 21A having no “thin portion” at the outer edge portion is provided as in the light receiving sensor 2A shown in FIG. It can also be prepared.

  In the light receiving sensor 2A (diffusion optical system 12A), components having the same functions as those of the light receiving sensor 2 (diffusion optical system 12) described above are denoted by the same reference numerals and redundant description is omitted. To do. In addition, regarding the function of the recess 22 when the measurement target light L is incident near the outer edge of the incident hole 11a in this light reception sensor 2A (such as the incidence of the measurement target light L from the inner side surface 22b), the light reception sensor 2 ( Since it is the same as the above-mentioned explanation regarding the diffusing optical system 12), the overlapping explanation is omitted.

  As described above, in the optical power meter 1 configured to include the light receiving sensor 2A, the measurement target light L that has passed through the incident hole 11a of the aperture 11 is disposed adjacent to the aperture 11 so as to be transmissive and diffuses the measurement target light L. A concave portion 22 is formed on one surface of the transmissive diffusion plate 21 on the aperture 11 side, and a part of the measurement target light L reflected on the bottom surface 22a of the concave portion 22 can enter the transmissive diffusion plate 21 from the inner side surface 22b of the concave portion 22. It is configured.

  Therefore, according to this optical power meter 1, in the same manner as the optical power meter prototyped by the applicant, the measurement object incident from the incident hole 11a by the amount provided with the diffusing reflection portion 31 in addition to the transmission diffusion plate 21A. The light L can be sufficiently diffused, whereby not only the incidence position dependency of the measurement target light L with respect to the incident hole 11a can be reduced, but also the incidence due to the presence of the recess 22 provided in the transmission diffusion plate 21A. When the measurement target light L is incident near the outer edge of the hole 11a, a part of the measurement target light L that has entered the diffuse reflection part 31 is reflected by the inner surface 31a of the diffuse reflection part 31 to the outside from the incident hole 11a. Even if it is emitted, a part of the measurement target light L that has passed through the incident hole 11a and reflected on the bottom surface 22a of the recess 22 enters the transmission diffusion plate 21A from the inner surface 22b of the recess 22. After being diffused in this manner, the light enters the diffuse reflection part 31. As a result, the amount of the measurement target light L finally incident on the photoelectric conversion unit 13 is increased by the amount of the measurement target light L. The dependency on the incident position of the target light L can be sufficiently reduced. Thereby, since the diameter of the diffuse reflection part 31 can be reduced without reducing the performance of the optical power meter 1, the optical power meter 1 can be sufficiently reduced in size, and the manufacturing cost of the diffuse reflection part 31 can be reduced. The manufacturing cost of the optical power meter 1 can be sufficiently reduced.

  In addition, the configuration of the light receiving sensors 2 and 2A including the diffusing optical systems 12 and 12A having the cylindrical diffuse reflection portion 31 obtained by cutting the resin sintered body has been described as an example. Then, like the diffuse reflection part 31x in the light receiving sensor 2x of the optical power meter prototyped by the applicant, a white diffuse reflection coating agent such as a barium sulfide powder-containing paint is applied to the inner surface of the cylindrical body (cylindrical body). A "diffuse reflection part" can also be configured (not shown). When such a configuration is adopted, the “incident allowable range defining portion (aperture)” may be configured by forming an “incident hole” in the central portion of the plate (not shown).

  Further, the configuration including the transmission diffusion plates 21 and 21A in which the inner diameter L2 of the concave portion 22 is larger than the diameter L1 of the incident hole 11a has been described as an example, but the inner diameter of the “concave portion” and the “incident hole” The diameter (inner diameter) may be the same. Further, the transmission diffusion plate 21 having the recess 22 formed so that the extending surface of the bottom surface 22a and the extending surface of the inner side surface 22b intersect at right angles has been described as an example. The “concave portion” can be formed so that the extended surface of the “inner side surface” intersects at an arbitrary angle other than a right angle. Specifically, a "concave part" is formed so that the inner diameter on the bottom surface side is larger than the inner diameter on the mouth edge side, or the inner diameter on the bottom surface side is smaller than the inner diameter on the mouth edge side. A “concave portion” can be formed so that

DESCRIPTION OF SYMBOLS 1 Optical power meter 2, 2A Light reception sensor 10 Casing 10a Bottom plate 11 Aperture 11a Incident hole 12, 12A Diffusion optical system 13 Photoelectric conversion part 21, 21A Transmission diffusion plate 22 Recessed part 22a Bottom face 22b Inner side surface 23 Thin part 31 Diffuse reflection part 31a Inner surface D2 Depth L Light to be measured L1 Diameter L2, L3a Inner diameter L3b Outer diameter T1, T2 Thickness

Claims (4)

A light that includes a photoelectric conversion unit that outputs a detection signal corresponding to the amount of light to be measured, and is configured to measure a predetermined optical parameter for the measurement target light based on the signal level of the detection signal A power meter,
An incident hole capable of passing the measurement target light is provided, and an allowable incidence range defining part for defining an allowable incidence range of the measurement target light to the optical power meter; and the measurement target light passing through the incident hole A transmission diffusing plate that is arranged adjacent to the allowable incidence range defining portion so as to be transmissive and diffuses the light to be measured, and is formed in a cylindrical shape, and the allowable incidence range defining portion and the transmissive diffusion plate are disposed on one end side. And a diffuse reflection unit that diffusely reflects the measurement target light transmitted through the transmission diffusion plate on the inner surface, and a part of the measurement target light diffused in the diffuse reflection unit is received by the photoelectric conversion unit Configured to be
The transmission diffuser plate has a concave portion formed on one surface on the incident allowable range defining portion side, passes through the incident hole, and reflects a part of the measurement target light reflected from the bottom surface of the concave portion from the inner side surface of the concave portion. An optical power meter configured so as to be incident on the transmission diffusion plate, and having a thin portion thinner than a thickness around the concave portion at an outer edge portion. A light that includes a photoelectric conversion unit that outputs a detection signal corresponding to the amount of light to be measured, and is configured to measure a predetermined optical parameter for the measurement target light based on the signal level of the detection signal A power meter,
An incident hole capable of passing the measurement target light is provided, and an allowable incidence range defining part for defining an allowable incidence range of the measurement target light to the optical power meter; and the measurement target light passing through the incident hole A transmission diffusing plate that is arranged adjacent to the allowable incidence range defining portion so as to be transmissive and diffuses the light to be measured, and is formed in a cylindrical shape, and the allowable incidence range defining portion and the transmissive diffusion plate are disposed on one end side. And a diffuse reflection unit that diffusely reflects the measurement target light transmitted through the transmission diffusion plate on the inner surface, and a part of the measurement target light diffused in the diffuse reflection unit is received by the photoelectric conversion unit Configured to be
The transmission diffuser plate has a concave portion formed on one surface on the incident allowable range defining portion side, passes through the incident hole, and reflects a part of the measurement target light reflected from the bottom surface of the concave portion from the inner side surface of the concave portion. An optical power meter configured to be incident on the transmission diffusion plate.   The optical power meter according to claim 1 or 2, wherein the transmission diffusion plate is formed such that an inner diameter of the concave portion is larger than a diameter of the incident hole.   A bottomed cylindrical casing is provided, and the incident hole is formed in the bottom plate so that the bottom plate in the casing functions as the incident allowable range defining portion, and is formed in a disk shape having a smaller diameter than the inner diameter of the casing. The transmissive diffuser plate and the diffuse reflection part formed in a cylindrical shape smaller in diameter than the inner diameter of the casing are accommodated in the casing and integrated with the casing. The optical power meter described in 1.

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