JPH0245737A - Transmissivity measuring instrument - Google Patents

Abstract

PURPOSE:To reduce the size of the instrument by constituting so as to measure the transmissivity of gas at the part sandwiched between a couple of transparent glass plates from the ratio of the quantities of reflected light and transmitted light. CONSTITUTION:When a reflecting mirror 31 is positioned on the optical axis of parallel luminous flux generated by a light emitting element 1, the parallel luminous flux from the element 1 is reflected by the mirror 31, passed through a lens 22 and a 2nd optical fiber, and converted by a photoelectric converting element 72 into an electric signal VR. Then when the mirror 31 is put off the optical axis of the parallel luminous flux from the element 1, the parallel luminous flux from the element 1 is transmitted through transparent glass 51 and 52, passed through a lens 23 and a 1st optical fiber, and converted by a photoelectric converting element 71 into an electric signal VS. Here, the signal VS varies in transmission quantity with the transparency of the gas at the part sandwiched between the glass plates 51 and 52. The transmissivity of the gas is therefore measured from the relative value between the signals VR and VS and the instrument is reduced in size.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an apparatus for measuring permeability in gas.

Conventional technology Inside a tunnel, visibility is poor due to exhaust gas and dust, so the transmittance in the air is measured and if the transmittance falls below a specified value, ventilation is provided by ventilating the tunnel.

As a device for measuring transmittance, for example, a measuring device as shown in FIG. 5 is used. The general structure consists of a light projecting section housed in a sealed case 91, a light receiving section housed in a sealed case 92, and an optical switch 11. The light projecting unit includes a light source 11, a lens 25 that converts the light emission output of the light source 11 into a parallel light beam,
A lens 27 that condenses a part of the parallel light beam and couples it into the first optical fiber, and an optical path blocking plate 81 that blocks the parallel light beam.
, a transparent glass plate 54 , and a dustproof hood 101 .

The optical switch 11 allows the light emitted from the first optical fiber to pass through or is blocked by the shutter 111, and couples the passed light into the second optical fiber again. The light receiving section includes a dustproof hood 102, a transparent glass plate 54, an optical path blocking plate 82, a lens 26 that converges a parallel light beam, a lens 28 that converts the light emitted from the second optical fiber into a parallel light beam, and a convergence member of the lens 26. It consists of a photoelectric conversion element 7 provided at a certain position.

Next, the operation of this measuring device will be described. The light source 11 is made to emit light, the light shielding plates 81 and 82 are moved to the positions indicated by the broken lines to block the light, and at the same time the light switch 1 is turned on.
The shutter 111 of No. 1 is moved to the position indicated by the broken line.

In this state, a part of the light that has been made into a parallel beam by the lens 25 is output to the lens 28 via the lens 27, enters the lens 26, and is guided to the photoelectric conversion element 7. The photoelectric conversion value at this time is taken as the reference value.

Next, the light blocking plates 81 and 82 are moved to the positions indicated by solid lines to allow light to pass therethrough, and at the same time, the shutter 111 of the optical switch 11 is moved to the position indicated by solid lines. In this state, the light that is made into a parallel beam by the lens 25 passes through the transparent glass plate, is output to the outside, propagates through the air, and reaches the light receiving section.

Let the photoelectric conversion value when the air is clear be the first measurement value.

Here, the relative relationship between the reference value and the first measured value is determined, and this is determined as the optimum value of the measurement conditions.

When the air is filled with droplets of exhaust gas or dust particles, the light propagating through the air collides with the particles and is scattered, so the amount of light reaching the light receiving section is attenuated and the photoelectric conversion value becomes small. This is used as the second measurement value to determine the relative relationship with the reference value, and if it falls below the set condition, ventilation is performed.

Problems to be Solved by the Invention In this type of measuring device, the light emitting part and the light receiving part are installed separated by several hundred meters, so it is very difficult to adjust the optical axis of the light emitting part and the light receiving part. Installation locations are limited to straight areas with good visibility.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a measuring device with a compact configuration and an extremely simple optical axis adjustment.

Means for Solving the Problems (First Means) In order to solve the above problems, the present invention provides a means for converting the light emission output into a parallel light beam, and a means for converging the parallel light beam and coupling it to a first optical fiber. means for inserting or removing a reflecting mirror fixed to a movable member on the optical axis of the parallel light flux obliquely to the optical axis; A means for coupling to an optical fiber and a pair of transparent glass plates provided on the optical axis of the parallel light beam are housed in a sealed case, and only the portion sandwiched between the pair of transparent glass plates is exposed. , when the reflecting mirror is located on the optical axis, the reference light quantity is obtained, and when the reflecting mirror is not on the optical axis, the transmitted light quantity in the gas is obtained, and transmitted through two optical fibers,
The transmittance in gas is measured by the ratio between the reference light amount and the transmitted light amount.

(Second Means) In order to solve the above-mentioned problems, the present invention provides a means for converting the light emission output into a parallel light beam, a means for converging the parallel light beam and coupling it to a first optical fiber, and a means for converting the light emission output into a parallel light beam. A branching filter inserted and fixed on the axis, a means for inserting or removing a reflecting mirror fixed to a movable member on the optical axis of the parallel light beam obliquely to the optical axis, and a pair of lenses that collect the reflected light from the branching filter. A means for guiding the parallel light beam to a reflecting mirror using a second optical fiber, and a pair of transparent glass plates provided on the optical axis of the parallel light beam are housed in a sealed case, and only the portion sandwiched between the pair of transparent glass plates is housed. When the reflecting mirror is located on the optical axis, the reference light amount is obtained, and when the reflecting mirror is not on the optical axis, the transmitted light amount in the gas is obtained and transmitted through one optical fiber, and the reference light amount is obtained. The transmittance in gas is measured by the ratio of the amount of light to the amount of transmitted light.

(Third Means) In order to solve the above-mentioned problems, the present invention provides a means for converting the light emission output into a parallel light beam, a means for converging the parallel light beam and coupling it to an optical fiber, and a means for converting the light emission output into a parallel light beam, and a means for converging the parallel light beam and coupling it to an optical fiber. A branching filter inserted and fixed, a means for inserting or removing a first reflection mirror fixed to a movable member on the optical axis of the parallel light beam obliquely to the optical axis, and a means for inserting or removing the first reflection mirror fixed to a movable member on the optical axis of the parallel light beam, and a third reflecting mirror to guide the parallel beam to the first reflecting mirror (the means and a pair of transparent glass plates provided on the optical axis of the parallel light beam are housed in a sealed case, and the pair of transparent glass plates When the first reflecting mirror is located on the optical axis, the reference light amount is obtained, and when the first reflecting mirror is not on the optical axis, the amount of light transmitted through the gas is obtained. It is transmitted through a single optical fiber, and the transmittance in the gas is measured by the ratio of the reference amount of light to the amount of transmitted light.

(Fourth Means) In order to solve the above problems, the present invention provides a plurality of slits on the circumference of a rotating body, and an optical member having a transparent glass plate fixed inside the slits. It is arranged in place of the pair of transparent glass plates of the second and third means, and is configured to change the position of the slit.

Effect: According to the above configuration, an apparatus with high measurement accuracy can be realized by the micro-optical configuration.

Example Embodiments of the present invention will be described with reference to the drawings.

(Example 1) FIG. 1 is a block diagram showing the optical configuration of a transmittance measuring device that is a first example of the present invention.

1 is a light emitting element; 21, 22, and 23 are, for example, focusing rod lenses; 31 is a reflecting mirror fixed to a movable member; 51
and 52 are transparent glass plates, 9 is a sealed case, and 71 and 72 are charging conversion elements.

When the reflection mirror 31 is moved to the broken line part, the parallel light beam is reflected and guided to the lens 22, focused by the lens 22, transmitted by the second optical fiber, and converted into an electric signal VR by the photoelectric conversion element 72. Next, when the reflecting mirror 31 is moved to the solid line part, the parallel light beam passes through the transparent glass plates 51 and 52 and is guided to the lens 23, where it is converged and the first
The signal is transmitted through an optical fiber and converted into an electrical signal Vs by a photoelectric conversion element 71. The amount of transmitted light of the electric signal Vs changes depending on the transparency of the gas in the portion sandwiched between the transparent glass plates 51 and 52. Therefore, the transmittance in the gas can be measured based on the relative values of the electrical signal VR and the electrical signal Vs.

(Embodiment 2) FIG. 2 is a block diagram showing the optical configuration of a transmittance measuring device according to a second embodiment of the present invention. 1 is a light emitting element, 21
22, 23, and 24 are, for example, focusing rod lenses, 4 is a branching filter, 32 is a reflecting mirror fixed to a movable member, 51 and 52 are transparent glass plates, 9 is a sealed case, and 7 is a photoelectric conversion element.

When the reflection mirror 32 is moved to the broken line part, the reflected light from the branching filter 4 is guided to the lens 22, reflected by the reflection mirror 32 via the lens 22, the second optical fiber, and the lens 24, and guided to the lens 23, where it is focused. The signal is transmitted through the first optical fiber, and converted into an electrical signal by the photoelectric conversion element 7 to obtain VR. Next, when the reflecting mirror 32 is moved to the solid line part, the transmitted light of the branching filter passes through the transparent glass plates 51 and 52, is guided to the lens 23, is focused by the lens 23, is transmitted by the first optical fiber, and is photoelectrically transmitted. The conversion element 7 converts it into an electrical signal to obtain Vs. Electric signal Vs is transmitted through transparent glass plate 51
The amount of transmitted light changes depending on the transparency of the gas in the portion sandwiched between Therefore, the transmittance in the gas can be measured based on the relative values of the electrical signal VR and the electrical signal Vs.

(Embodiment 3) FIG. 3 is a block diagram showing the optical configuration of a transmittance measuring device according to a third embodiment of the present invention.

1 is a light emitting element, 21 and 23 are focusing rod lenses, 4 is a branching filter, 32 is a reflection mirror fixed to a movable member, 33 and 34 are reflection mirrors, 51 and 52 are transparent glass plates, 9 is a sealed case, 7 is a photoelectric conversion element.

When the reflection mirror 32 is moved to the broken line part, the light reflected by the branching filter 4 is reflected by the reflection mirrors 33 and 34 and the reflection mirror 32, guided to the lens 23, focused, transmitted through an optical fiber, and converted into electricity by the photoelectric conversion element 7. It is converted into a signal to obtain VR. Next, when the reflection mirror 32 is moved to the solid line part, the transmitted light of the branching filter passes through the transparent glass plates 51 and 52, is guided to the lens 23, is focused by the lens 23, is transmitted by the optical fiber, and is transmitted to the photoelectric conversion element. 7, it is converted into an electrical signal to obtain Vs. The amount of transmitted light of the electric signal Vs changes depending on the transparency of the gas in the portion sandwiched between the transparent glass plates 51 and 52. Therefore, the transmittance in the gas can be measured based on the relative values of the electric signal vR and the electric signal Vs.

(Embodiment 4) Figure 4 shows the first to third embodiments of the present invention, in which when the transparent glass block plate is exposed, fine particles such as exhaust gas and dust particles adhere to the surface and the transparency deteriorates. This is a rotating glass block body that replaces the transparent glass block plates 51 and 52 to prevent measurement errors from occurring. 62 is a slit, 53 is a transparent glass plate, and 61 is a rotating shaft.

This is to maintain the transparency of the transparent glass plate by periodically moving the slit section through rotational control.

Effects of the Invention According to the present invention, a transmittance measuring device in which optical axis adjustment is extremely simple can be realized, and the device can be downsized.

[Brief explanation of the drawing]

1, 2, and 3 are block diagrams showing the configuration of a transmittance measuring device according to an embodiment of the present invention, and FIG. 4 is a rotating glass block body used in the transmitting part of the transmittance measuring device of the present invention. FIG. 5 is a block diagram showing the structure of a conventional example. 1... Light emitting element, 11... Light source, 21-28...
Lenses, 31-34...Reflection mirror 4...Branch filter 5...Transparent glass plate, 6...Rotating glass block body, 61...Slit, 7, 71, and 72...
・Photoelectric conversion elements, 81 and 82... Optical path blocking plates, 9 and 9
1 and 92... sealed case, 10... dustproof hood, 1
1...Light switch. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (5)

[Claims] (1) A light emitting element, a first lens that converts the light emitting output of the light emitting element into a parallel light beam, and a first lens located on the optical axis of the first lens to focus the parallel light beam and couple it into a first optical fiber. a second lens located at the output end of the first lens and changing the optical path by being inserted diagonally with respect to the optical axis; a third lens that focuses and couples into the second optical fiber; a pair of transparent glass plates disposed on the optical axis between the reflective mirror and the second lens;
It is composed of a photoelectric conversion element that converts the emitted light of the optical fiber into an electrical signal, and the ratio of the amount of reflected light to the amount of transmitted light is 1.
A transmittance measuring device characterized by measuring transmittance in gas at a portion sandwiched between a pair of transparent glass plates. (2) a light emitting element, a first lens that converts the light emitting output of the light emitting element into a parallel light beam, and a first lens located on the optical axis of the first lens that focuses the parallel light beam and couples it into a first optical fiber; a branching filter positioned at the output end of the first lens and inserted and fixed obliquely to the optical axis; and a branching filter that focuses reflected light from the branching filter and couples it into a second optical fiber. a third lens that converts the output light of the second optical fiber into a parallel beam; and a fourth lens that is arranged at the input end of the second lens and inserted obliquely to the optical axis. A reflective mirror that blocks the output light of the first lens and guides the output light of the fourth lens to the second lens, and a photoelectric conversion element that converts the output light of the first optical fiber into an electrical signal. A transmittance measuring device characterized in that the transmittance of a gas in a portion sandwiched between a pair of transparent glass plates is measured based on the ratio of the amount of branched light and the amount of transmitted light. (3) Instead of the third and fourth lenses and the second optical fiber, a pair of reflecting mirrors is used to guide the reflected light from the branching filter to the reflecting mirror. Transmittance measuring device according to item 2. (4) The transmittance measuring device according to claim 1, 2, or 3, characterized in that it is configured so that only the portion sandwiched between a pair of transparent glass plates is exposed. (5) Instead of a pair of transparent glass plates, a pair of optical members each having a plurality of slits provided on the circumference of the rotating body and a transparent glass plate attached inside the plurality of slits is arranged; 4. The transmittance measuring device according to claim 1, 2 or 3, wherein the optical member is configured to be rotated by remote control to maintain the clarity of the transparent glass plate.