JP7343169B2 - Gas concentration measurement method and gas concentration measurement device for sealed packaging containers - Google Patents

Description

The present invention relates to a gas concentration measuring method for a sealed packaging container that can measure the concentration of a specific gas inside with high precision, and a gas concentration measuring device used in the method.

BACKGROUND ART Conventionally, hermetically sealed packaging containers, such as retort molded containers (for example, retort rice packs) that are gas-substituted and sealed, have been widely used.
In the packaging process for this type of sealed packaging container, after removing oxidizing gases (e.g. oxygen) that may shorten the shelf life or shelf life of the packaged product remaining in the head space, nitrogen, carbon dioxide, etc. Gas replacement packaging is performed in which gas replacement is performed with an inert gas and the packaging is sealed (Patent Document 1). As a result, oxidation-causing gases within the sealed packaging container are removed, and the packaged items, especially foods, can have a long shelf life and shelf life.

In the inspection process after gas replacement packaging, an inspection is performed to see if the concentration of oxidation-causing gas, particularly oxygen, is below a predetermined value.

However, the currently mainstream method for measuring gas concentration is a sampling test in which a syringe needle is inserted into a sealed packaging container arbitrarily selected as a sample, and the composition of a small amount of gas sucked from inside the sealed packaging container is examined. During this sampling inspection, sealed packaging containers with injection marks must be discarded. Furthermore, if the number of samples is increased in order to improve the inspection accuracy, the inspection time becomes longer, and the increased amount of waste results in increased economic and time losses. Furthermore, when the head space without the filled packaged object is narrow, it is extremely difficult to measure the gas concentration.

Patent No. 3742042

Therefore, an object of the present invention is to enable the gas concentration of a sealed packaging container to be able to measure the concentration of a specific gas inside with high precision, without damaging the sealed packaging container, even when the head space where there is no packaged object is narrow. An object of the present invention is to provide a measuring method and a gas concentration measuring device used in the method.

What solves the above problem is a gas concentration measuring method in which the concentration of a specific gas in a sealed packaging container filled with an object to be packaged, gas replaced, and packaged is measured using a gas concentration measuring device, the method comprising: has a main body portion having a space for filling a packaged object therein, and a measuring portion having a communication portion communicating with a head space in the main body portion and a space for laser light transmission, The device includes a laser generator that emits a laser beam of a specific wavelength, a laser receiver that receives the laser beam, and a laser beam that transmits the laser beam of the specific wavelength to the portion to be measured of the sealed packaging container. a laser-type gas concentration meter that measures the gas concentration of a specific gas remaining inside the container; and a reflective surface capable of reflecting the laser beam, the laser beam being emitted from the laser generating section and hitting the measured portion of the sealed packaging container. The gas concentration measuring method is characterized in that the transmitted laser light is reflected by the reflective surface and then made to enter the laser light receiving section (claim 1).

The reflective surface includes a first reflective surface and a second reflective surface that are arranged parallel to each other to face each other with the portion to be measured of the sealed packaging container sandwiched therebetween, and the reflective surface reflects the laser beam to the first reflective surface and the second reflective surface. It is preferable to reflect the light a plurality of times between the light and the surface (Claim 2).

Moreover, what solves the above-mentioned problem is a gas concentration measuring device that measures the concentration of a specific gas in a sealed packaging container filled with an object to be packaged, replaced with gas, and packaged, wherein the sealed packaging container has an internal The gas concentration measuring device has a main body portion having a space for filling a packaged object, and a measuring portion having a communication portion communicating with a head space in the main body portion and a space for transmitting laser light, the gas concentration measuring device comprising: a laser generator that emits a laser beam of a specific wavelength; a laser receiver that receives the laser beam; and a laser beam that transmits the laser beam of a specific wavelength to the portion to be measured of the sealed packaging container and enters the inside of the sealed packaging container. A laser gas concentration meter that measures the gas concentration of a specific gas remaining; and a laser that has a reflective surface capable of reflecting the laser beam, and that is emitted from the laser generating section and transmitted through the measured portion of the sealed packaging container. The gas concentration measuring device is characterized in that the gas concentration measuring device is configured to make light enter the laser light receiving section after being reflected by the reflecting surface.

The gas concentration measuring device includes a first housing that includes the laser generating section and a second housing that includes the laser receiving section, and the reflective surface is connected to the part to be measured of the sealed packaging container. has a first reflective surface and a second reflective surface that are arranged to face each other in parallel with each other in between, the first reflective surface has a first window portion that emits the laser beam, and the first reflective surface or the second reflective surface has a The second reflective surface includes a second window into which the laser beam enters, and the laser beam emitted from the first window is reflected multiple times between the first reflective surface and the second reflective surface. It is preferable that the light is configured such that the light is then incident on the second window portion (claim 4). The first reflective surface and the second reflective surface are provided so that a relative separation distance can be adjusted, and when the first reflective surface and the second reflective surface sandwich the portion to be measured of the sealed packaging container. It is preferable that the first window part and the second window part, and the first reflective surface and the second reflective surface are configured to be in close contact with the part to be measured of the sealed packaging container. Item 5).

According to the gas concentration measuring method according to claim 1, the concentration of a specific gas inside can be measured with high precision without damaging the sealed packaging container, even when the head space where there is no packaged object is narrow. Can be done.
According to the gas concentration measuring method according to the second aspect, the optical path length of the laser beam can be made longer, and the concentration of the specific gas inside the sealed packaging container can be measured with higher precision.
According to the gas concentration measuring device according to claim 3, the concentration of the specific gas inside can be measured with high precision without damaging the sealed packaging container, even when the head space where there is no packaged object is narrow. Can be done.
According to the gas concentration measuring device according to the fourth aspect, the optical path length of the laser beam can be made longer, and the concentration of the specific gas inside the sealed packaging container can be measured with higher precision.
According to the gas concentration measuring device according to the fifth aspect, the effects of the third aspect can be more easily achieved.

FIG. 3 is an explanatory diagram for explaining the operation of an embodiment of a sealed packaging container used in the gas concentration measuring method of the present invention. FIG. 2 is a front view of the sealed packaging container shown in FIG. 1. FIG. FIG. 2 is a right side view of the sealed packaging container shown in FIG. 1. FIG. 2 is a plan view of the sealed packaging container shown in FIG. 1. FIG. FIG. 2 is a front view showing the sealed packaging container shown in FIG. 1 in use. 1 is a plan view of an embodiment of a gas concentration measuring device used in the gas concentration measuring method of the present invention. 7 is a plan view of the gas concentration measuring device shown in FIG. 6. FIG. 8 is a partially enlarged view of the gas concentration measuring device shown in FIG. 7. FIG. 8 is a view taken along the line AA in FIG. 7. FIG. FIG. 7 is a view taken along the line B-B in FIG.

In the present invention, the laser beam emitted from the laser generating part 11 and transmitted through the measurement target part 7 of the sealed packaging container 1 is reflected by the reflective surface 14 and then incident on the laser receiving part 12, thereby damaging the sealed packaging container. The present invention has realized a gas concentration measuring method and a gas concentration measuring device for a sealed packaging container, which can measure the concentration of a specific gas inside with high precision even when the head space without an object to be packaged is narrow.

First, an embodiment of a sealed packaging container used in the gas concentration measuring method of the present invention will be described using an embodiment shown in FIGS. 1 to 5.
The sealed packaging container 1 of this embodiment is a sealed packaging container 1 capable of measuring the concentration of a specific gas inside, and includes a main body 3 having an object filling space 2 inside, and a head inside the main body 3. It has a communicating portion 5 communicating with the space 4 and a measuring portion 7 having a space 6 for transmitting laser light. Each configuration will be described in detail below.

The sealed packaging container 1 of this embodiment is a container for retort cooked rice, and the specific gas inside is oxygen. However, the sealed packaging container of the present invention is not limited to this, and as shown in FIG. The term 4 includes a wide range of sealed packaging containers in which gas concentration cannot be accurately measured due to narrowness, and also includes sealed packaging containers containing specific gases other than oxygen.

Inside the main body 3, there is provided a packing space 2 for filling the packing object (cooked rice in this embodiment).In this embodiment, the main body 3 and the packing space 2 Although it is formed into a substantially rectangular parallelepiped, the shape is not limited to a rectangular parallelepiped, and any shape is included within the scope of the present invention.

The measurement target part 7 has a laser light transmission space 6 therein, is a part for measuring the concentration of a specific gas by transmitting the laser light, and has a communication part communicating with the head space 4 in the main body part 3. It is provided adjacent to the main body part 3 via 5. However, although the part to be measured 7 in this embodiment is provided separately adjacent to the main body part 3, it is not limited to this, and can measure the concentration of a specific gas by transmitting a laser beam. Any form may be used as long as it exists, and for example, a structure in which a space for filling the packaged object and a space for transmitting laser light are partitioned by a partition plate or the like within the main body is also included in the scope of the present invention. It is preferable that the measurement target section 7 has a structure in which only the gas in the head space 4 is transferred via the communication section 5, but moisture and It may be one in which a small amount of the packaged object S is transferred.

The sealed packaging container 1 of this embodiment is integrally molded of a transparent material (for example, polypropylene, etc.) in order to transmit a laser beam to the part to be measured 7 to measure the concentration of a specific gas. However, the sealed packaging container of the present invention is not limited to this, and only the part constituting the part to be measured may be formed of a transparent material, and furthermore, the sealed packaging container of the present invention may be made of a transparent material. The main body portion and/or the measured portion may be formed of a material that can transmit laser light of a specific wavelength. Note that in the present application, the term "transparent material" broadly includes transparent or translucent materials, regardless of whether they are colored or not. In addition, in this application, materials that can transmit laser light of a specific wavelength include materials that can transmit laser light of a specific wavelength, regardless of whether they are transparent or translucent, materials, patterns, characters, figures, etc. added, or colored. broadly encompasses

Further, it is preferable that the laser beam transmission space 6 of the portion to be measured 7 is formed into an elongated shape as in this embodiment. Thereby, the optical path length of the laser beam can be ensured longer, and the measurement accuracy of the specific gas concentration can be improved. In the sealed packaging container 1 of this embodiment, a film F is adhered to the upper surface to maintain the sealed state of the packaged object filling space 2, the communication portion 5, and the laser beam transmission space 6.

Next, a method for measuring gas concentration in a sealed packaging container according to the present invention will be explained using an embodiment shown in FIGS. 6 to 10.
The gas concentration measuring method using the sealed packaging container 1 of this embodiment is to measure the concentration of a specific gas in the sealed packaging container 1 filled with an object to be packaged S, replaced with gas, and packaged using the gas concentration measuring device 10. In the method for measuring gas concentration, a sealed packaging container 1 has a main body 3 having an object filling space 2 therein, a communication part 5 communicating with a head space 4 in the main body 3, and a laser beam transmitting device. The gas concentration measuring device 10 includes a laser generating section 11 that emits a laser beam of a specific wavelength, a laser receiving section 12 that receives the laser beam, and a measuring section 7 that has a space 6 for measuring the specific wavelength. A laser gas concentration meter 13 that transmits laser light to the measurement target part 7 of the sealed packaging container 1 to measure the gas concentration of a specific gas remaining inside the sealed packaging container 1, and a reflective surface 14 that can reflect the laser light. Gas concentration measurement characterized in that a laser beam emitted from a laser generating section 11 and transmitted through a measurement target section 7 of a sealed packaging container 1 is reflected by a reflecting surface 14 and then made incident on a laser receiving section 12. It's a method. Although detailed description will be given below, the sealed packaging container 1 is as described above, and its explanation will be omitted.

The gas concentration measuring method of this embodiment is a method of measuring the gas concentration of a specific gas remaining in the sealed packaging container 1, and is carried out at an inspection site where the sealed packaging container 1 is inspected before shipping. This is done in the inspection process of a rotary type or pillow type packaging machine that has various processes related to this.

In the gas concentration measuring method of this embodiment, the remaining specific gas is oxygen gas (O ₂ ). In the packaging process of a packaging machine, which is carried out in an atmospheric environment, when an object to be packaged is filled, the inside of the sealed packaging container is also filled with atmospheric air.
Oxidizing gases such as oxygen gas contained in the atmosphere cause oxidation and deterioration of packaged items, especially foods. Therefore, after the packaging process of filling the sealed packaging container with the item to be packaged, the packaging machine evacuates the atmosphere from the sealed packaging container and fills it with an inert gas, such as nitrogen gas (N ₂ ), carbon dioxide gas, etc. A gas replacement (gas purge) step is provided to replace the gas with (CO ₂ ).

Thereafter, the gas concentration measuring method according to this embodiment is a method of measuring the gas concentration of oxygen gas in the sealed packaging container 1 that has been replaced with gas, and inspecting whether the gas concentration is below a reference value. When measuring the gas concentration of oxygen gas, if the gas concentration is below the standard value, gas replacement has been performed normally and the inside of the sealed packaging container 1 is filled with inert gas, so the packaged items can prevent oxidation and extend shelf life and shelf life. On the other hand, if the gas concentration exceeds the standard value, the product is determined to be defective and is discharged, for example, in the packaging process (defective product discharge process) of a packaging machine.

As shown in FIG. 8, the gas concentration measuring device 10 used in the gas concentration measuring method of this embodiment is a laser beam equipped with a laser generating section 11 that emits a laser beam and a laser receiving section 12 that receives the laser beam. It has a type gas concentration meter 13 and a reflective surface 14 that reflects laser light.

The laser gas concentration meter 13 is configured to be able to analyze a specific gas by wavelength tunable semiconductor laser absorption spectroscopy.

Here, Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a technique that uses a predetermined incident light intensity of a laser beam output from a semiconductor laser element and a gas containing a specific gas to be measured. In this method, the transmittance is determined from the transmitted light intensity of the laser light after passing through a sealed cell and absorbed by the specific gas, and the gas concentration is measured from the absorbance of the laser light based on the transmittance. .

It is known that each gas, including a specific gas, has its own absorption wavelength band, and that the absorption wavelength band includes a plurality of absorption lines related to wavelengths that more strongly absorb light. TDLAS modulates and amplifies the wavelength of the output laser light in the near-infrared region so that it matches the specific wavelength of one of the multiple absorption lines of the specific gas to be measured. It is composed of Then, the gas concentration is measured by determining the absorbance of the laser beam based on the absorption spectrum of a specific wavelength that changes before and after passing through the cell. In this example, the gas to be measured is oxygen gas, and the cell that seals the gas to be measured is the sealed packaging container 1.

The laser generating section 11 includes a laser light source and a control section that sets the wavelength of the laser light emitted from the laser light source to a specific wavelength and adjusts the light intensity to a predetermined light intensity.
The laser light source includes a semiconductor laser element made of a wavelength-tunable diode and is configured to be able to output laser light in the near-infrared region. The control unit adjusts the wavelength of the laser light output from the semiconductor laser element to a specific wavelength specific to the specific gas to be measured, and performs control to amplify the laser light so that it is emitted with a predetermined incident light intensity. is formed.

Here, since the specific gas measured by the laser gas concentration meter 13 according to this embodiment is oxygen gas, the absorption wavelength band specific to the oxygen gas is the 760 nm band, and the plurality of absorption wavelength bands included in the absorption wavelength band are 760 nm. A specific wavelength related to one of the absorption lines is selected as the output wavelength of the laser beam.

The laser generator 11 is built into a first housing 15, and the first housing 15 has a laser emission window 16. The laser emission window 16 is fitted with sapphire glass that easily transmits light in the near-infrared region. The laser generating section 11 is formed to emit a laser beam from the first housing 15 through the laser emitting window section 16.

The inside of the first housing 15 is formed so that it can be evacuated or gas replaced (gas purge) in order to remove a specific gas, oxygen gas in this embodiment. Therefore, the first housing 15 is configured to be able to maintain a vacuum or be filled with an inert gas such as nitrogen gas or carbon dioxide. This can prevent the laser light from being absorbed by the specific gas within the first housing 15 until it is emitted from the laser light source through the laser emission window 16, improving the accuracy of gas concentration measurement. can be done.

The laser light receiving section 12 has a light receiving sensor that receives the laser light that has passed through the portion to be measured 7 of the sealed packaging container 1, and a measuring section that measures the gas concentration based on the light receiving signal from the light receiving sensor.

The light receiving sensor is composed of an element, such as a photodiode, that converts the transmitted light intensity of the laser beam transmitted through the measurement target part 7 of the sealed packaging container 1 into an electrical transmitted light signal. Thereby, the transmitted light intensity of the laser beam transmitted through the portion to be measured 7 of the sealed packaging container 1 can be electrically processed.

The measurement unit calculates the transmittance based on the transmitted light signal related to the transmitted light intensity and the incident light signal related to the incident light intensity of the laser beam output from the laser generator 11, and calculates the transmittance based on the transmittance. The absorbance of the specific gas is determined, and the concentration of the specific gas in the portion to be measured 7 of the sealed packaging container 1 is measured based on the absorbance.

The laser light receiving section 12 is built into the second housing 17. The second housing 17 has a window 18 for receiving laser light. Like the laser emission window 16, the laser reception window 18 is fitted with sapphire glass that easily transmits light in the near-infrared region. Thereby, the laser light receiving section 12 is formed so as to receive the laser light that has passed through the portion to be measured 7 of the sealed packaging container 1 through the laser light receiving window section 18 .

Similarly to the first housing 15, the inside of the second housing 17 is also formed to be able to be evacuated or replaced with gas. Therefore, it is possible to prevent the laser light from being absorbed by the specific gas in the second housing 17 until the light receiving sensor receives the laser light that is incident through the laser light receiving window 18, thereby measuring the gas concentration. accuracy can be improved.

In this manner, the laser gas concentration meter 13 emits a laser beam from the laser generating section 11 through the laser emission window section 16, and transmits the laser beam into the measured section 7 of the sealed packaging container 1 to be measured. The laser light receiving section 12 is configured to receive the laser light that has passed through the measurement target part 7 of the sealed packaging container 1 through the laser light receiving window section 18 .

The gas concentration measuring device 10 having the laser type gas concentration meter 13 allows the laser beam emitted from the laser emission window section 16 to enter the laser reception window section 18 at least once on the reflective surface 14. Preferably, it is configured to be reflected multiple times.

The reflective surface 14 of this embodiment consists of a first reflective surface 14a in which a first window portion 19 is provided at a predetermined position, and a second reflective surface 14b in which a second window portion 20 is provided in a predetermined position. , the first reflective surface 14a and the second reflective surface 14b are provided so as to face each other in parallel. The first reflective surface 14a and the second reflective surface 14b are made of, for example, a mirror surface, a mirror-polished metal, or a mirror-like film attached to a predetermined base material, and are formed to be able to reflect laser light. has been done.

The relative distance between the first reflecting surface 14a and the second reflecting surface 14b can be adjusted (they can be relatively approached or separated) by a reciprocating mechanism (not shown) (a mechanism including a cylinder or a driving device such as a servo motor). In FIG. 8, the portion to be measured 7 of the sealed packaging container 1 can be held between the first reflective surface 14a and the second reflective surface 14b at the upper and lower sides. Therefore, when the portion to be measured 7 of the sealed packaging container 1 is held between the first reflective surface 14a and the second reflective surface 14b from above and below, the first reflective surface is placed on the upper and lower surfaces of the portion to be measured 7 of the sealed packaging container 1, respectively. 14a and the second reflective surface 14b are configured to be brought into close contact with each other.

Furthermore, by determining the positions of the first window part 19 and the second window part 20 with respect to the part to be measured 7 of the sealed packaging container 1, the part to be measured of the sealed packaging container 1 is 7, the first window portion 19 and the second window portion 20 can also be brought into close contact with the portion to be measured 7 of the sealed packaging container 1. As a result, when the laser beam is emitted from the first window section 19, reflected by the second reflective surface 14b and the first reflective surface 14ab, and made to enter the second window section 20, the specific gas contained in the atmosphere The influence of gas can be minimized, and the concentration of a specific gas can be measured with higher accuracy.

Note that the positions of the first window section 19 and the second window section 20 are such that the first reflective surface 14a and the second reflective surface 14b are positioned so that the laser beam is emitted from the first window section 19 and enters the second window section 20. The distance between the first window section 19 and the second window section 20 and the distance between the first window section 19 and the second window section 20 when the laser beam emitted from the first window section 19 is incident on the second reflective surface 14b are sufficient. Depending on the relationship with the incident angle, the laser beam can be controlled to be reflected a predetermined number of times between the first reflective surface 14a and the second reflective surface 14b and to be incident on the second window portion 20.

When the laser beam is emitted from the first window part 19 and is made to enter the second reflective surface 20, the incident angle of the laser beam can be arbitrarily set between 5 degrees and 85 degrees, and the angle of incidence of the laser beam can be arbitrarily set between 5 degrees and 85 degrees. When the incident angle is 5 degrees or less, the optical path length can be easily calculated based on the distance between the first window section 19 and the second reflecting surface 14b. The difference in optical path length is not large compared to the case of . On the other hand, when the incident angle is 85 degrees or more, a larger proportion of the transmitted laser light is scattered than absorbed by the specific gas, which may lead to errors in gas concentration measurement.

Further, the number of times of reflection between the first reflective surface 14a and the second reflective surface 14b is preferably about 2 to 4 times. If the laser beam is reflected five times or more, the optical path length can be increased, but the attenuation rate of the laser beam increases, so a highly sensitive light-receiving sensor must be provided in the laser light-receiving section 12. Therefore, there is a possibility that the cost will increase.

Next, specific operations of the gas concentration measuring method and gas concentration measuring device of the present invention will be explained using an example shown in the drawings.

In the gas concentration measuring method and gas concentration measuring device 10 of the present invention, as shown in FIG. 6 or 7, the sealed packaging containers 1 placed on the belt Y of the conveyor W are sequentially and intermittently conveyed. The sealed packaging container 1 is placed on the belt Y so that the longitudinal direction of the portion 7 to be measured of the sealed packaging container 1 is transported in the transport direction (arrow H direction) in FIG.

Then, when the part to be measured 7 of the sealed packaging container 1 reaches between the first reflective surface 14a and the second reflective surface 14b of the gas concentration measuring device 10 near the location where the gas concentration measuring device 10 is installed, as shown in FIG. As shown in FIG. 2, the first reflective surface 14a and the second reflective surface 14b of the gas concentration measuring device 10 sandwich the measured portion 7 from above and below.

After the part to be measured 7 of the sealed packaging container 1 is sandwiched between the first reflecting surface 14a and the second reflecting surface 14b, the laser emitting window 16 and the first window 19 of the first reflecting surface 14a are removed from the laser generating section 11. A laser beam is emitted from above to the portion to be measured 7 of the sealed packaging container 1 through the laser beam. The laser beam is first reflected by the second reflective surface 14b, then reflected by the first reflective surface 14a, then the second reflective surface 14b, and then reflected by the second window 19 of the first reflective surface 14a and the second housing 17. The laser beam is received by the laser light receiving section 12 through the laser light receiving window section 18 .

The light-receiving sensor of the laser light-receiving section 12 converts the laser light that has passed through the measurement target section 7 of the sealed packaging container 1 into an electronic transmitted light signal, and the transmitted light signal is output to the measurement section. The measuring section acquires the transmitted light signal and an incident light signal obtained by electronically converting the laser light emitted by the laser generating section 11, compares the transmitted light signal and the incident light signal, and compares the transmitted light signal with the incident light signal to determine whether the laser light is in a sealed packaging container. The transmittance T for the part to be measured 7 of No. 1 is measured. Then, based on the transmittance T, the absorbance of the absorption spectrum of the specific wavelength of the laser beam absorbed by the specific gas in the measurement target part 7 of the sealed packaging container 1 is calculated, and based on the absorbance, the sealed packaging container 1 The gas concentration of the specific gas in the measured part 7 is measured.

In this embodiment, the reflective surface 14 is configured to consist of two surfaces, the first reflective surface 14a and the second reflective surface 14b, but the configuration is not limited to this. For example, for one reflective surface, The optical path length can also be increased by reflecting the laser light.

1 Sealed packaging container 2 Packaging space 3 Main body section 4 Head space 5 Communication section 6 Laser light transmission space 7 Measurement section 10 Gas concentration measuring device 11 Laser generating section 12 Laser receiving section 13 Laser type gas concentration meter 14 Reflection Surface 14a First reflective surface 14b Second reflective surface 15 First housing 16 Laser emission window 17 Second housing 18 Laser reception window 19 First window 20 Second window,
F Film w Conveyor Y Belt S Item to be packaged

Claims (5)

A gas concentration measuring method in which the concentration of a specific gas in a sealed packaging container filled with an object to be packaged, gas replaced, and packaged is measured using a gas concentration measuring device, the method comprising:
The sealed packaging container has a main body portion having a space for filling a packaged object therein, and a measuring portion having a communication portion communicating with a head space in the main body portion and a space for transmitting laser light,
The gas concentration measuring device includes a laser generator that emits a laser beam of a specific wavelength, a laser receiver that receives the laser beam, and a laser beam that transmits the laser beam of the specific wavelength to the portion to be measured of the sealed packaging container. A laser gas concentration meter that measures the gas concentration of a specific gas remaining inside the sealed packaging container, and a reflective surface that can reflect the laser beam,
A method for measuring a gas concentration, characterized in that a laser beam emitted from the laser generating section and transmitted through the measuring section of the sealed packaging container is reflected by the reflecting surface and then made incident on the laser receiving section. The reflective surface includes a first reflective surface and a second reflective surface that are arranged parallel to each other to face each other with the portion to be measured of the sealed packaging container sandwiched therebetween, and the reflective surface reflects the laser beam to the first reflective surface and the second reflective surface. 2. The gas concentration measuring method according to claim 1, wherein the gas concentration is reflected multiple times between the gas and the surface. A gas concentration measuring device that measures the concentration of a specific gas in a sealed packaging container filled with a packaged object, replaced with gas, and packaged,
The sealed packaging container has a main body portion having a space for filling a packaged object therein, and a measuring portion having a communication portion communicating with a head space in the main body portion and a space for transmitting laser light,
The gas concentration measuring device includes a laser generator that emits a laser beam of a specific wavelength, a laser receiver that receives the laser beam, and a laser beam that transmits the laser beam of the specific wavelength to the portion to be measured of the sealed packaging container. A laser gas concentration meter that measures the gas concentration of a specific gas remaining inside the sealed packaging container, and a reflective surface that can reflect the laser beam,
A gas characterized in that the laser beam is emitted from the laser generating section and passes through the measured portion of the sealed packaging container, and is configured so that the laser beam is reflected by the reflecting surface and then made to enter the laser receiving section. Concentration measuring device. The gas concentration measuring device includes a first housing containing the laser generating section and a second housing containing the laser receiving section,
The reflective surface has a first reflective surface and a second reflective surface that are arranged to face each other in parallel with the measured portion of the sealed packaging container in between,
The first reflective surface includes a first window portion through which the laser beam is emitted, and the first reflective surface or the second reflective surface includes a second window portion through which the laser beam enters,
Claim: The laser beam emitted from the first window is configured to be reflected multiple times between the first reflective surface and the second reflective surface and then enter the second window. 3. The gas concentration measuring device according to 3. The first reflective surface and the second reflective surface are provided so that a relative separation distance can be adjusted, and when the first reflective surface and the second reflective surface sandwich the portion to be measured of the sealed packaging container. 5. The first window portion, the second window portion, the first reflective surface, and the second reflective surface are configured to be in close contact with the portion to be measured of the sealed packaging container. gas concentration measuring device.

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