JP2012047525A - Inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection device which is capable of directly inspecting displacement of a condenser lens in a lens probe and of performing inspection with respect to a lens probe installed under a high-temperature environment.SOLUTION: An inspection device 10 inspects displacement of an optical axis of a condenser lens 22 attached to a holder 21. The inspection device includes: an optical fiber bundle 11 which comprises a plurality of optical fibers 11a and has a front end surface disposed in or in the vicinity of a focus position of the condenser lens 22; and a position detecting element 12 which is disposed on the rear end side of the optical fiber bundle 11.

Description

  The present invention relates to a condensing lens inspection apparatus used for a ferrule probe or the like.

Conventionally, a radiation thermometer (pyrometer, infrared radiation thermometer) that measures the temperature of a measurement object by detecting the wavelength and intensity of light emitted from the measurement object and converting the detected light into an electrical signal by a light receiving element or the like Etc.) are known.
In such a radiation thermometer, a ferrule probe that transmits light emitted from the measurement target to the light receiving element when the temperature of the measurement target is high and the light receiving element or the like cannot be installed in the vicinity of the measurement target is used.

An optical fiber is used for the ferrule probe (for example, see Non-Patent Documents 1 and 2).
In addition, a condensing lens is usually disposed between the measurement target and the optical fiber. The intensity of the light to be detected can be increased by condensing the light from the measurement object by the condensing lens and making it incident on the optical fiber of the ferrule probe. Further, by increasing the light intensity in this way, accurate and stable temperature measurement can be performed.

  By the way, the condensing lens that is arranged in front of the ferrule probe and collects light in this way is attached to the tip of the cylindrical holder, and further fixed to the holder by brazing or the like to be a lens probe. Then, the holder is detachably attached to the tip of the ferrule probe so that the condensing lens and the optical fiber end face of the ferrule probe are aligned. That is, the optical axis alignment and focusing can be performed simply by attaching the holder to the ferrule probe.

  However, in the above-described lens probe, the condensing lens may be attached while being inclined with respect to the holder, and may be fixed in a state of being displaced as it is. Then, of course, when this lens probe is attached to the tip of the ferrule probe and the temperature of the measurement target is measured, accurate measurement cannot be performed.

  Therefore, conventionally, for such a lens probe, a power meter is used as an inspection device, and the positional deviation of the condenser lens is inspected by optical performance evaluation. Specifically, a ferrule probe without a lens probe is used as a reference sample, and the light transmittance (light intensity) of the reference sample is measured with the power meter to obtain a reference value. In addition, the ferrule probe to which the lens probe is attached is used as a test sample, and the light transmittance (light intensity) of the test sample is measured with the power meter to obtain the test value. And the presence or absence of position shift of a condensing lens is evaluated by comparing the obtained inspection value with a reference value.

Noboru Ichinose, Tetsuji Kobayashi, “Sensors and their applications”, Sogo Publishing Co., 1980, P47 Kiyoshi Takahashi, “Introduction to Sensor Technology”, Industrial Research Committee, 1978, P39

  However, in the optical performance evaluation using a conventional power meter as an inspection device, the light transmittance (light intensity) simply decreases when the condensing lens is attached to the holder and is displaced. However, there is a problem that the condensing lens is tilted in which direction, and thus the position where the light incident on the condensing lens is condensed cannot be confirmed.

However, the alignment between the condenser lens and the end face of the optical fiber of the ferrule probe does not require so high accuracy, and even if there is a slight misalignment, for example, the sensitivity of the radiation thermometer, etc. will only decrease. It is. Accordingly, even a lens probe whose positional deviation has been confirmed can be used as it is without being reassembled. However, even in that case, if it is possible to confirm where the light incident on the condenser lens is focused, more accurate measurement is possible by adjusting the sensitivity of the measuring instrument such as a radiation thermometer. Become. Accordingly, there is a need for an inspection apparatus that can directly inspect the positional deviation of the condenser lens.
Also, when you want to inspect an existing lens probe, especially when it is installed in a high temperature environment, it is difficult to directly inspect the misalignment of the condenser lens. There is a need for an inspection apparatus that can also be used.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to directly inspect the positional deviation of the condenser lens in the lens probe and to a lens probe installed in a high temperature environment. An object of the present invention is to provide an inspection apparatus that can perform inspection.

The inspection apparatus of the present invention is an inspection apparatus that inspects an optical axis shift of a condensing lens attached to a holder,
An optical fiber bundle consisting of a plurality of optical fibers, the tip surface of which is arranged at or near the focal position of the condenser lens;
And a position detecting element disposed on the rear end side of the optical fiber bundle.

  According to this inspection apparatus, the light collected by the condenser lens can be transmitted to the position detection element (PSD) by the optical fiber bundle composed of a plurality of optical fibers. The light incident on each optical fiber is guided to the rear end side of the incident optical fiber as it is without being transmitted to other optical fibers, and is incident on the position detecting element. The light is incident on the position detection element (PSD) as it is without changing the position.

  The position detection element (PSD) is an element that can detect at which position on the light receiving surface the light is received. Therefore, the position of the light received from the optical fiber bundle, that is, the distribution when entering the optical fiber bundle. It receives light in the same distribution state as the state. Therefore, depending on the distribution state of the light detected by the position detection element, whether or not the distribution state of the received light is biased with respect to the preset correct distribution state, and what is the bias when there is a bias. It is possible to detect whether or not it has.

  Even when the condensing lens is installed in a high temperature environment, the optical fiber vandal has high heat resistance. Therefore, the position detection element (PSD) is placed at a position where the influence of the high temperature is small by making it an appropriate length. By doing so, it becomes possible to directly inspect the positional deviation of the condenser lens installed in such a high temperature environment.

In the inspection apparatus, the condensing lens attached to the holder has an incident portion, a cable portion, and a connector portion, and transmits light from the measurement target to the light receiving element by an optical fiber provided therein. It is preferable that the ferrule probe configured as described above is disposed in front of the incident portion and used to collect light on the incident end face of the optical fiber.
In this way, the condenser lens is used by being arranged in front of the entrance part of the ferrule probe. Therefore, even when the condenser lens is mainly installed in a high temperature environment, the condenser lens is used as described above. It is possible to directly inspect the misalignment.

According to the inspection apparatus of the present invention, as described above, it is detected whether or not the distribution state of the light detected by the position detection element is biased, and if there is a bias, what kind of bias is present. Therefore, it is possible to directly inspect the position deviation of the condensing lens in the lens probe, that is, the optical axis deviation, from the detected deviation. In addition, the positional deviation (optical axis deviation) of the condenser lens can be directly inspected even with respect to a lens probe installed in a high temperature environment.
Therefore, based on the obtained positional deviation (optical axis deviation) of the condenser lens, for example, by adjusting the sensitivity on the measurement device side such as a radiation thermometer, more accurate measurement is performed using the condenser lens. be able to.

It is a figure which shows schematic structure of the inspection apparatus which concerns on this invention, Comprising: It is a sectional side view which shows the usage condition of an inspection apparatus. It is a schematic block diagram of a ferrule probe. It is a figure which shows schematic structure of the lens probe which concerns on this invention, Comprising: It is a sectional side view which shows the usage condition of a lens probe. (A) is a side view of an optical fiber vandal, (b) is a figure which shows the end surface of an optical fiber vandal.

  Hereinafter, an inspection apparatus according to the present invention will be described in detail with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

FIG. 1 is a diagram showing a usage pattern of an inspection apparatus according to the present invention. In FIG. 1, reference numeral 10 denotes an inspection apparatus, and 20 denotes a lens probe to be inspected.
First, the lens probe 20 will be described. The lens probe 2 is used by being attached to the distal end side of the ferrule probe 1 shown in FIG. 2, for example.

  The ferrule probe 1 is used in a pyrometer (not shown) which is a kind of radiation thermometer. The pyrometer is a measuring device that measures the wavelength of light emitted from a measurement target (not shown) and measures the temperature of the measurement target. Since the measurement object has a high temperature (e.g., about 750 ° C. to 1000 ° C.) that emits visible light by burning red and white, a light receiving element that converts light into an electrical signal is installed at a position away from the measurement object. There is a need to. Therefore, a ferrule probe 1 that transmits light from the measurement target to the light receiving element is used.

The ferrule probe 1 has a flexible cable shape, includes an incident portion 2, a cable portion 3, and a connector portion 4, and has an optical fiber 5 for optical transmission (see FIG. 3) inside. It is a thing.
The incident portion 2 is provided at one end of the ferrule probe 1 and is a portion where light emitted from the measurement target is incident. As shown in FIG. 3, the incident end surface 5a of the optical fiber 5 is arranged at the tip. It is a thing.

Further, the lens probe 20 is used by being attached to the incident portion 2 of the ferrule probe 1. As shown in FIGS. 3 and 1, the lens probe 20 is attached to a substantially cylindrical holder 21 and the tip of the holder 21. Condensing lens 22 is included.
The holder 21 is made of a metal such as stainless steel or an alloy, and has a positioning portion 23 for the incident portion 2 of the ferrule probe 1 at the rear end portion and an attachment portion 24 for the condenser lens 22 at the tip end portion. Is.

  The positioning portion 23 has a cylindrical portion 23a formed with a larger diameter than the tip end side of the holder 21, and an annular step portion 23b provided between the tip end side of the holder 21 and the cylindrical portion 23a. Thus, as shown in FIG. 3, the positioning plate 2a provided in the incident portion 2 of the ferrule probe 1 is brought into contact with the step portion 23b. With such a configuration, the ferrule probe 1 condenses light by inserting the distal end side of the incident portion 2 into the cylindrical portion 23a of the positioning portion 23 of the lens probe 20 and bringing the attachment portion 24 into contact with the step portion 23b. Positioning with respect to the lens 22 is possible.

  The mounting portion 24 has a larger inner diameter at the front end portion of the holder 21 than the rear end side of the holder 21, and the mounting portion 24 has a stepped portion 24a formed by changing the inner diameter. The condenser lens 22 is positioned by bringing the rear end into contact therewith.

  The condensing lens 22 is a sapphire convex lens (sapphire lens), and has a substantially cylindrical shape with a front surface serving as a light receiving surface formed in a convex shape. The rear end portion of the condensing lens 22 is a large diameter portion 22a formed to have a larger diameter than the front end side, and the inner diameter of the large diameter portion 22a is substantially equal to the inner diameter of the mounting portion 24 of the holder 21. It is formed in agreement. With such a configuration, the condensing lens 22 is positioned with respect to the holder 21 by fitting the large-diameter portion 22a into the mounting portion 24 and bringing the rear end surface into contact with the stepped portion 24a. Yes.

  In addition, after the condenser lens 22 is positioned with respect to the holder 21 in this manner, the condenser lens 22 is brazed between the distal end side of the large diameter portion 22a and the receiving portion 24, so that the holder 21 is fixed to the holder 21. It is fixed (the description of the brazing material is omitted). Therefore, when the condensing lens 22 is correctly positioned and fixed with respect to the holder 21, the lens probe 20 comprising the condensing lens 22 and the holder 21 is placed on the incident portion 2 of the ferrule probe 1 as shown in FIG. When attached, the focal point of the condenser lens 22 is positioned on the incident end face 5 a of the optical fiber 5.

However, when the condenser lens 22 is positioned with respect to the holder 21, for example, the condenser lens 22 may be inclined and fixed by brazing as shown by a two-dot chain line in FIG.
Therefore, in order to inspect the positional deviation of the condensing lens 22 in the lens probe 20, particularly the optical axis deviation, the inspection apparatus 10 according to the present embodiment includes the optical fiber bundle 11 and the position as shown in FIG. 1. The detection element 12 is provided.

  As shown in FIGS. 4 (a) and 4 (b), the optical fiber bundle 11 has a large number (for example, several tens) of optical fibers 11a having the same diameter and length such that the end surfaces are substantially circular. About hundreds of bundles are formed into a cylindrical shape. The optical fiber 11a is made of, for example, quartz and has heat resistance of about 1000 ° C. However, the material of the optical fiber 11a is not limited to quartz, and may be, for example, a glass fiber formed of glass having high heat resistance.

The optical fiber bundle 11 may be, for example, bonded between the optical fibers 11a with an adhesive and fixed in a cylindrical shape as a whole. The outer periphery of the bundle 11 is fixed with an adhesive tape or the like. Furthermore, the whole may be fixed in a columnar shape by being accommodated in a cylindrical holding tube (not shown).
By bundling a large number of optical fibers 11a in this manner, the entire end surface (front end surface and rear end surface) is substantially circular as shown in FIG. 4B. Therefore, the end face of each optical fiber 11 a constitutes a part of the end face of the optical fiber bundle 11.

  Further, in this embodiment, the cylindrical optical fiber bundle 11 has an outer diameter that substantially matches the inner diameter of the holder 21 of the lens probe 20 (the inner diameter between the mounting portion 24 and the positioning portion 23) as shown in FIG. Thus, when the optical fiber bundle 11 is inserted into the holder 21, the central axis of the optical fiber bundle 11 and the central axis of the holder 21 coincide with each other.

  Further, in the present embodiment, an annular positioning portion 13 is provided on the outer peripheral portion of the cylindrical optical fiber bundle 11. The positioning portion 13 is disposed at a position corresponding to the positioning plate 2a of the ferrule probe 1 shown in FIG. That is, the position of the positioning unit 13 is such that the length from the front end surface of the optical fiber bundle 11 to the positioning unit 13 matches the length from the front end surface of the incident unit 2 to the positioning plate 2a in the ferrule probe 1. Determined and arranged.

  Note that the length of the optical fiber bundle 11, that is, the length of the optical fiber 11a is not particularly limited, and is appropriately determined according to the state of the lens probe 20 to be inspected, the length of the holder 21, and the like. . That is, when the lens probe 20 is installed in a high temperature environment, the length of the optical fiber bundle 11 is reduced so that the influence of the high temperature on the position detection element 12 arranged on the rear end side of the optical fiber bundle 11 is reduced. Is formed long enough. When the lens probe 20 is inspected as a product before it is set at the measurement location (before being used), it is simply formed in an appropriate length corresponding to the length of the holder 21.

  The position detection element 12 includes a PSD (Position Sensitive Detector), and has a light receiving surface 12a having a predetermined area uniformly coated with a material that generates a voltage corresponding to the amount of light, and a light spot on the light receiving surface 12a. When hit, a voltage corresponding to the amount of light is generated. Since the potential at the point away from the spot position is lowered by the resistance of the film material, the position of the light spot can be obtained from the ratio of the voltages generated at both ends of the sensor, for example.

With such a configuration, the position detecting element 12 detects the position (incident position) of light incident on the light receiving surface 12a with one detector, and the detected light position is continuously detected as an electrical signal from the electrode 12b. It is designed to output.
Therefore, the position detection element (PSD) 12 has a light receiving surface 12a disposed opposite to a rear end surface of the optical fiber bandal 11, that is, an output surface, and the electrode 12b includes, for example, a PSD signal processing circuit (not shown). Are to be connected.

  The optical fiber bundle 11 and the position detection element 12 may be bonded and fixed by, for example, a transparent adhesive, or may be held in a state in which they are fixed by a cylindrical holding member (not shown). . Further, the light receiving surface 12a of the position detecting element 12 may be aligned with the rear end surface of the optical fiber bundle 11 during use, and in this state, these may be held and fixed using appropriate holding means.

Next, the inspection of the lens probe 20 by the inspection apparatus 10 of this embodiment will be described. Here, the case where the lens probe 20 is inspected before being set at the measurement location (before being used) will be described.
First, as shown in FIG. 1, with respect to the lens probe 20 to be inspected, the distal end side of the optical fiber bandal 11 is inserted into the rear end side of the holder 21, that is, the positioning portion 23 side, and the positioning portion 13 is inserted into the holder 21. Are brought into contact with the stepped portion 23a of the positioning portion 23. Thereby, the front end surface of the optical fiber bandal 11 is disposed at or near the focal position of the condenser lens 22.

  In this state, for example, the inspection light source 7 disposed in front of the condenser lens 22 is turned on. Then, the light irradiated from the light source 7 to the condenser lens 22 is condensed by the condenser lens 22. At this time, if the condensing lens 22 is correctly attached and fixed to the holder 21, the condensing position by the condensing lens 22 is on the central axis of the holder 21 as shown in FIG. On the center axis of the fiber bandal 11. In addition, the condenser lens 22 correctly attached and fixed to the holder 21 as described above is used as a reference, and this is inspected in advance by the inspection apparatus 10, and the inspection result at that time, that is, the light Is stored as a reference distribution.

  As described above, if the condensing position by the condensing lens 22 is on the central axis of the holder 21, the light transmitted through the optical fiber vandal 11 and emitted to the light receiving surface 12 a of the position detection element (PSD) 12 is the optical fiber vandal. 11 has the highest intensity at the center of the light receiving surface 12a corresponding to the central axis of 11, and the intensity decreases toward the periphery. Therefore, if such a light intensity distribution (distribution state) is obtained, it is determined that the condenser lens 22 is correctly attached to the holder 21 and fixed.

Further, for example, when the condenser lens 22 is tilted and fixed as shown by a two-dot chain line in FIG. 1, and its optical axis is deviated, the focal position deviates from the central axis of the holder 21, and the light It will also come off from the center axis of the fiber bandal 11.
When the optical fiber bandal 11 receives light from the condensing lens 22 in such a state where the focal position is off the central axis, each optical fiber 11a is not transmitted to the other optical fiber 11a and is directly moved to the rear end side. Therefore, the received light is made incident on the light receiving surface 12a of the position detecting element (PSD) 12 in a distribution state as received at the tip surface, that is, a distribution state in which the light receiving position is biased.

  The position detection element (PSD) 12 receives light of the same distribution state as the distribution state when entering the optical fiber bundle 11 by the light receiving surface 12a, detects the position (incident position) of the light, and detects the detected light. Are continuously output as electrical signals from the electrode 12b. Therefore, by reading the output by a PSD signal processing circuit or the like connected to the electrode 12b of the position detection element (PSD) 12, the distribution state of the light emitted from the condenser lens 22 and incident on the optical fiber bundle 11 is determined. Can be detected. That is, it is possible to detect whether or not the distribution state of the received light is biased, and what bias is present when there is a bias. In addition, in particular, when there is a bias, it can be detected by comparing with the reference distribution of the reference lens probe described above, for example, to detect what the bias is.

  Therefore, according to the inspection apparatus 10 of the present embodiment, whether or not the distribution state of the light detected by the position detection element (PSD) is biased, and what is the bias when there is a bias. Therefore, the positional deviation of the condenser lens 22 in the lens probe 20, that is, the optical axis deviation can be directly inspected from the detected deviation. Therefore, based on the obtained positional deviation (optical axis deviation) of the condenser lens 22, for example, by adjusting the sensitivity on the measuring instrument side such as a radiation thermometer, the condenser lens 22 of the lens probe 20 is used. More accurate measurement can be performed.

Further, in the above-described embodiment, the lens probe 20 is in a state before being set at a measurement place (before being used). However, for example, even when the lens probe 20 is installed in a high temperature environment, Inspection can be performed using the inspection apparatus of the invention.
That is, when inspecting the positional deviation (optical axis deviation) of the condenser lens 22 of the lens probe 20 installed in such a high temperature environment, the length is particularly long as the optical fiber bandal 11. Therefore, the optical fiber bundle 11 having a sufficiently long length is used so that the influence of high temperature on the position detecting element (PSD) 12 disposed on the rear end side of the optical fiber bandal 11 is reduced.

Except for using such an optical fiber bandal 11, the positional deviation (optical axis deviation) of the condenser lens 22 is inspected in the same manner as in the above embodiment.
Then, since the optical fiber bandal 11 composed of the plurality of optical fibers 11a has high heat resistance, the position detection element (PSD) 12 is arranged at a position where the influence of the high temperature is small by making the length of the optical fiber 11a to an appropriate temperature environment. The positional deviation of the condenser lens 22 in the lens probe 20 installed below can also be directly inspected.

  Accordingly, the lens probe 20 installed in a high temperature environment is adjusted by adjusting the sensitivity on the measurement device side such as a radiation thermometer based on the obtained positional deviation (optical axis deviation) of the condenser lens 22. Even if the condenser lens 22 is used, more accurate measurement can be performed.

  The preferred embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiments, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention. It is.

  For example, in the above embodiment, the optical fiber bandal 11 is configured by bundling several tens to several hundreds of optical fibers 11a. However, the present invention is not limited to this, and a plurality of, for example, four or more. An optical fiber bandal may be configured by bundling these optical fibers. However, since the number of the optical fibers 11a determines the resolution of the inspection apparatus of the present invention, the number of the optical fibers 11a is required when it is desired to obtain the positional deviation (optical axis deviation) of the condenser lens with higher accuracy. If high accuracy is not required so much, the number may be about 4 to several tens.

  Further, in the above embodiment, the central axis of the optical fiber bundle 11 can be obtained by making the outer diameter of the optical fiber bundle 11 substantially coincide with the inner diameter of the holder 21 of the lens probe 20 and inserting the optical fiber bundle 11 into the holder 21. However, depending on the number of optical fibers 11a constituting the optical fiber bundle 11, the outer diameter thereof may be significantly different from the inner diameter of the holder 21 of the lens probe 20. .

  In that case, for example, the outer diameter of the positioning portion 13 shown in FIG. 1 is preferably substantially matched with the inner diameter of the cylindrical portion 23 a in the positioning portion 23 of the holder 23. By doing so, even when the outer diameter of the optical fiber bundle 11 is significantly different from the inner diameter of the holder 21 of the lens probe 20, the optical fiber bundle 11 is inserted by inserting the optical fiber bundle 11 into the holder 21. Can be made to coincide with the central axis of the holder 21.

  Further, when the outer diameter of the optical fiber bundle 11 substantially matches the inner diameter of the holder 21 of the lens probe 20, the position of the focus of the condenser lens 22 is detected without providing the positioning portion 13 in the optical fiber bundle 11. By detecting with the element 12, the position of the front end surface of the optical fiber bundle 11 with respect to the condenser lens 22 may be determined. That is, when the tip end side of the optical fiber bundle 11 is inserted into the holder 21, light from the condenser lens 22 is received by the position detection element 12 in that state. Then, while moving the position of the front end surface of the optical fiber bundle 11 back and forth, the intensity of light detected by the position detection element 12 is examined, and the position where the focal point of the condenser lens 22 becomes the front end surface of the optical fiber bundle 11 is determined. Find and align there.

  When the front end surface of the optical fiber bundle 11 is adjusted to the focal position of the condenser lens 22 in this way, the positional deviation (optical axis deviation) of the condenser lens 22 is inspected as described above. In this way, it is possible to perform a displacement inspection of the condenser lens 22 with higher sensitivity.

DESCRIPTION OF SYMBOLS 1 ... Ferrule probe, 2 ... Incident part, 5 ... Optical fiber, 5a ... Fiber end surface, 10 ... Inspection apparatus, 11 ... Optical fiber bandal, 12 ... Position detection element, 12a ... Light-receiving surface, 20 ... Lens probe, 21 ... Holder , 22 ... Condensing lens

Claims (2)

An inspection device for inspecting an optical axis shift of a condenser lens attached to a holder,
An optical fiber bundle consisting of a plurality of optical fibers, the tip surface of which is arranged at or near the focal position of the condenser lens;
A position detecting element disposed on a rear end side of the optical fiber bundle. The condensing lens attached to the holder has an incident portion, a cable portion, and a connector portion, and is configured to transmit light from a measurement target to a light receiving element by an optical fiber provided inside. The inspection apparatus according to claim 1, wherein the inspection apparatus is disposed in front of the incident portion of the probe and used to collect light on an incident end face of the optical fiber.

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