WO2021035432A1

WO2021035432A1 - Gas analyzer

Info

Publication number: WO2021035432A1
Application number: PCT/CN2019/102333
Authority: WO
Inventors: Tong Zhou WANG; Dong Li; Xiao Bo YANG; Chuan Yu Zhang; Yao Lei KANG; Jian Yong ZHANG
Original assignee: Siemens Aktiengesellschaft; Siemens Ltd., China
Priority date: 2019-08-23
Filing date: 2019-08-23
Publication date: 2021-03-04
Also published as: CN113767274A; EP3994447A4; EP3994447A1

Abstract

A gas analyzer includes: a light source (110); an optical splitter (150), dividing light emitted by the light source into measurement light and reference light; a measurement arm (510) and a reference arm (530), wherein gas to be measured is filled in the measurement arm, reference gas is filled in the reference arm, the measurement light propagatively passes through the measurement arm, and the reference light propagatively passes through the reference arm; an optical detector (750), receiving light propagatively passing through the measurement arm and light propagatively passing through the reference arm, and converting the received light into electrical signals; and a coder (300), disposed between the optical splitter and the measurement arm and the reference arm, wherein the coder is configured to code one of the measurement light and the reference light and block the other one of the measurement light and the reference light. Therefore, the structure of the gas analyzer may be simplified.

Description

GAS ANALYZER

BACKGROUND

Technical Field

The present invention relates to a gas analyzer.

Related Art

A gas analyzer, also called a gas analysis instrument, may be configured to analyze gas components. For example, as a gas analyzer, an optical gas analyzer analyzes gas components by using a feature that specific components in gas have different absorption rates on light of specific wavelengths. Specifically, light may firstly illuminate a gas to be analyzed. Then, light transmissively passing through the gas to be analyzed may be received by means of a photoelectric sensor, to obtain the intensity of the light transmissively passing through the gas to be analyzed. Components in the gas to be analyzed absorb light of specific wavelengths and the intensity of light transmissively passing through the gas to be analyzed becomes smaller, and therefore, for example, by comparing the decreased intensity of the light transmissively passing through the gas to be analyzed with an intensity of reference light, the components and contents thereof in the gas to be analyzed may be determined.

SUMMARY

The present invention is to solve the foregoing and/or other technical problems and provides a gas analyzer.

According to an exemplary embodiment, a gas analyzer includes: a light source; an optical splitter, dividing light emitted by the light source into measurement light and reference light; a measurement arm and a reference arm, where gas to be measured is filled in the measurement arm, reference gas is filled in the reference arm, the measurement light propagatively passes through the measurement arm, and the reference light propagatively passes through the reference arm; an optical detector (750) , receiving light propagatively passing through the measurement arm and light propagatively passing through the reference arm, and converting the received light into electrical signals; and a coder (300) , disposed between the optical splitter and the measurement arm and the reference arm, where the coder is configured to code one of the measurement light and the reference light and block the other one of the measurement light and the reference light.

The gas analyzer includes a grating, disposed between the light source and the optical splitter, where the grating is configured to separate the light emitted from the light source into a plurality of beams of light of different wavelengths.

The gas analyzer includes a lens unit, an optical coupler, and a position regulator, where the lens unit is configured to guide the light propagatively passing through the measurement arm and the light propagatively passing through the reference arm to enter the optical coupler, the optical coupler is configured to guide the light guided by the lens unit to illuminate the optical detector, and the position regulator is configured to regulate a position of the optical detector, so that the optical detector is located at a focus of the optical coupler.

The coder includes: coding patterns, configured to allow at least one part of one of the measurement light or the reference light to transmissively pass through the coding patterns and to be propagated to the measurement arm or the reference arm, to code the beam of light; and light shielding patterns, configured to block the other one of the measurement light or the reference light from transmissively passing through the light shielding patterns.

The coding patterns include a plurality of coding patterns different from each other, and the coder is configured to code one of the measurement light or the reference light in preset time by means of one of the plurality of coding patterns different from each other and block the other one of the measurement light and the reference light.

The coding patterns include a plurality of coding patterns different from each other, and the coder is configured to code one of the measurement light or the reference light in a preset time period by means of a plurality coding patterns in the plurality of coding patterns different from each other and block the other one of the measurement light and the reference light.

The coding patterns include coding patterns complying with a Welsh-Hadamard algorithm, and the coder is configured to code one of the measurement light or the reference light by means of the patterns complying with the Welsh-Hadamard algorithm and block the other one of the measurement light and the reference light.

The coder includes a circular coding chip, where the coding patterns are located on at least one sector of the circular coding chip.

The circular coding chip is configured to rotate between the optical splitter and the measurement arm and the reference arm, so that the sector where the coding patterns are located is located at a first position between the optical splitter and the measurement arm to code the measurement light or is located at a second position between the optical splitter and the reference arm to code the reference light.

The light shielding patterns are located at a sector of the circular coding chip symmetrical with the sector where the coding patterns are located relative to a circle center of the circular coding chip, so that the sector where the coding patterns are located is located at the first position between the optical splitter and the measurement arm to block the reference light when the measurement light is coded, or the sector where the coding patterns are located is located at the second position between the optical splitter and the measurement arm to block the measurement light when the reference light is coded.

The coder includes a display, where the display is configured to display the coding patterns at the first position between the optical splitter and the measurement arm to code the measurement light, or display the coding patterns at the second position between the optical splitter and the reference arm to code the reference light.

The display is configured to, when the coding patterns are displayed at the first position, display the light shielding patterns at the second position to block the reference light, or when the coding patterns are displayed at the second position, display blocking patterns at the first position to block the measurement light.

The display includes at least one of a liquid crystal display and a digital micro-mirror device.

the gas analyzer includes: a processor, configured to receive the electrical signal from the optical detector, and obtain information related to the gas to be measured according to the received electrical signal.

The coder includes coding patterns, and the coding patterns are configured to allow at least one part of one of the measurement light or the reference light to transmissively pass through the coding patterns and to be propagated to the measurement arm or the reference arm, to code the beam of light, where the processor is configured to be capable of performing decoding processing on a received electrical signal corresponding to coded light by using a time-wavelength mapping algorithm, a Fourier transform algorithm and a Welsh-Hadamard transform algorithm.

According to the exemplary embodiments, the coder including the coding patterns and the light shielding patterns is disposed between a light source unit and a measurement unit; when one of the measurement light and the reference light is coded, the other one of the measurement light and the reference light may be blocked, so that in a same time, only the coded measurement light or only the coded reference light passes through the gas to be measured or the reference gas and reaches the measurement unit. Therefore, the gas analyzer according to the exemplary embodiments may have a simplified structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The following accompanying drawings are designed to schematically describe and explain the present invention, and are not intended to limit the range of the present invention, where:

FIG. 1 is a schematic structural diagram showing a gas analyzer according to an exemplary embodiment;

FIG. 2 is a schematic diagram showing a coder according to an exemplary embodiment; and

FIG. 3 is a schematic diagram showing the rotation of a coder according to an exemplary embodiment.

List of reference numerals:

100 Light source unit; 300 Coder; 500 Measurement unit;

700 Detection unit; 900 Processor

110 Light source; 13 Grating; 150 Optical splitter

510 Measurement arm; 530 Reference arm

710 Lens unit; 530 Optical coupler; 750 Optical detector; 770 Position regulator

DETAILED DESCRIPTION

To make technical features, objectives and effects of the present invention understood more clearly, specific implementations of the present inventions will be described with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram showing a gas analyzer according to an exemplary embodiment. As shown in FIG. 1, the gas analyzer may include a light source unit 100, a coder 300, a measurement unit 500, and a detection unit 700.

The light source unit 100 may include a light source 110 and an optical splitter 150. The light source 110 may emit light (as the solid arrow line shown in Fig. 1) of specific wavelengths, used for performing gas analysis. The light source 110 may be a single light source emitting light of one wavelength, or a composite light source emitting light of a plurality of wavelengths. For example, when the light source 110 is implemented as a compound light source, the light source unit 100 may include a grating 130 disposed between the light source 110 and the optical splitter 150, so that the grating may separate composite light of a plurality of wavelengths emitted from the light source into a plurality of beams of light of different wavelengths. In this way, the separated light of different wavelengths may illuminate different positions of the coder 300 after passing through the optical splitter 150.

The optical splitter 150 may divide light emitted by the light source 110 into measurement light and reference light (as the solid arrow lines shown in Fig. 1) having different directions. Herein, the measurement light and the reference light transmissively passing through the optical splitter 150 may have a same optical intensity. For example, when the light source 110 is configured as a composite light source emitting composite light of a plurality of wavelengths, the optical splitter 150 may respectively divide a plurality of beams of light that pass through the grating 130 and are separated into a plurality of light whose wavelengths are different from each other, into measurement light and reference light having different directions, so that a plurality of beams of light included in the measurement light and a plurality of beams of light included in the reference light may be same with each other and may have a same optical intensity. In other words, in addition to illumination to the measurement arm 510 and the reference arm 530, the measurement light and the reference light may be same with each other. However, the exemplary embodiment is not limited thereto, the measurement light and the reference light may include light of a specific wavelength and a specific intensity respectively, and finally, it is acceptable that an initial wavelength and an initial intensity of the light is considered when gas analysis is carried out according to the intensity of light passing through the measurement arm 510 and the reference arm 530.

The coder 300 may be disposed between the optical splitter 150 and the measurement arm 510 and the reference arm 530. As shown in the following content to be described, the coder 300 may code one of the measurement light and the reference light and blocks the other one of the measurement light and the reference light. In other words, the measurement light may be coded by the coder 300 and then pass through the measurement arm 510 (as the solid arrow line shown in Fig. 1) , and the reference light may be blocked by the coder 300 and does not pass through the reference arm 530; or, the reference light may be coded by the coder 300 and then pass through reference arm 530 ( (as the solid arrow line shown in Fig. 1) ) , and the measurement light may be blocked by the coder 300 and does not pass through the measurement arm 510. Therefore, the gas analyzer 300 may be configured to be a specific structure according to the exemplary embodiment. Detailed descriptions are provided below.

The measurement unit 500 may be disposed on an optical path on which light passing through the coder 300 is projected. The measurement unit 500 may include a measurement arm 510 and a reference arm 530. Gas to be measured may be filled in the measurement arm 510. For example, the measurement arm 510 may include a gas inlet and a gas outlet. The gas to be measured may enter an internal space of the measurement arm 510 from the gas inlet, flows along a direction shown in FIG. 1, and finally flows out of the gas outlet of the measurement arm 510 (as the dotted arrow line shown in Fig. 1) . Therefore, the measurement arm 510 may be made from a transparent material, to allow the measurement light to transmissively passes through the gas to be measured that flows in the internal space of the measurement arm 510, and then to be emitted out to a detection unit 700. In addition, the gas to be measured may be filled in the reference arm 530. For example, the reference arm 530 may include a gas inlet and a gas outlet. Reference gas may enter an internal space of the measurement arm 530 from the gas inlet, flows along a direction shown in FIG. 1, and finally flows out of the gas outlet of the reference arm 530 (as the dotted arrow line shown in Fig. 1) . Therefore, the reference arm 530 may be made from a transparent material, to allow the measurement light to transmissively pass through the gas to be measured that flows in the internal space of the reference arm 530, and then to be emitted out to the detection unit 700.

The detection unit 700 may include a lens unit 710, an optical coupler 730, an optical detector 750, and a position regulator 770. The lens unit 710, the optical coupler 730 and the position regulator 770 may be configured to enable light emitted out of the measurement unit 500 to be propagated to the optical detector 750. For example, the lens unit may guide the light propagatively passing through the measurement arm and the light propagatively passing through the reference arm to enter the optical coupler, and then, the optical coupler may guide the light guided by the lens unit, to illuminate to the optical detector. In addition, the position regulator may regulate a position of the optical detector, so that the optical detector is located at a focus of the optical coupler.

The optical detector 750 may receive the light propagatively passing through the measurement arm 510 and the light propagatively passing through the reference arm 530, and converts the received light into electrical signals. Herein, the electrical signals may be related to the intensity of light received by the optical detector 750 (light intensity) , and the optical detector 750 may be an element, for example, a photoelectric sensor (for example, a CMOS) capable of converting light into an electrical signal.

The gas analyzer according to the exemplary embodiments may further include a processor or processing unit 900. The processor 900 may receive the electrical signal from the optical detector, and may obtain information related to the gas to be measured according to the received electrical signal, so as to complete the gas detection.

Operations corresponding to the coder 300 and the processor 900 according to an exemplary embodiment will be described below in details by referring to FIG. 2 and FIG. 3. FIG. 2 is a schematic diagram showing a coder according to an exemplary embodiment; and FIG. 3 is a schematic diagram showing the rotation of a coder according to an exemplary embodiment.

As shown in FIG. 2, the coder 300 may include

coding patterns

1A, 2A, 3A, and 4A and

light shielding patterns

1B, 2B, 3B, and 4B. The

coding patterns

1A, 2A, 3A, and 4A may be patterns allowing at least one part of one of the measurement light or the reference light to transmissively pass through and to be propagated to the measurement arm 510 or the reference arm 530. "Allow at least one part of light to transmissively pass through" herein refers to "coding" the beam of light. In other words, in addition to the light transmissive part allowing light to transmissively pass through, the

coding patterns

1A, 2A, 3A, and 4A may further include a light shielding part blocking the light from transmissively passing through. For example, as shown in FIG. 2, the coding patterns 1A may merely include a light transmissive part, and does not block the light at all. The

coding patterns

2A, 3A, and 4A may include a light shielding part, and may further include a light transmissive part. In another aspect, the

light shielding patterns

1B, 2B, 3B, and 4B may be patterns merely including the light shielding part blocking the light from transmissively passing through. Therefore, light cannot transmissively pass through the

light shielding patterns

1B, 2B, 3B, and 4B. In other words, the

light shielding patterns

1B, 2B, 3B, and 4B may be same with each other.

Herein, the coder 300 may allow the coding patterns to code one of the measurement light or the reference light, and meanwhile, allows the light shielding patterns to block the other one of the measurement light and the reference light. In this way, in the same time, only one of the coded measurement light or the coded reference light may transmissively pass through the gas to be measured or the reference gas and is incident to the optical detector 750. In this way, the processor 900 may determine a signal from the optical detector 750 corresponds to which one in the measurement light and the reference light according to a current state of the coder 300 (that is, which one in the measurement light and the reference light is being coded and which one in the measurement light and the reference light is being blocked by the coder 300) .

As shown in FIG. 2, in an exemplary embodiment, the coder 300 may include or is implemented as a circular coding chip. The

coding patterns

1A, 2A, 3A, and 4A are located on at least one sector of the circular coding chip. The circular coding chip may rotate between the optical splitter and the measurement arm and the reference arm. In this way, a sector where the coding patterns are located may be located at a position (afirst position) between the optical splitter and the measurement arm to code the measurement light, or located at a position (asecond position) between the optical splitter and the reference arm to code the reference light.

In addition, the

light shielding patterns

1B, 2B, 3B, and 4B may be located at a sector of the circular coding chip symmetrical with the sector where the

coding patterns

1A, 2A, 3A, and 4A are located relative to a circle center of the circular coding chip. For example, the coding patterns 1A may be symmetrical with the light shielding patterns 3B, the coding patterns 2A may be symmetrical with the light shielding patterns 4B, the coding patterns 3A may be symmetrical with the light shielding patterns 1B, and the coding patterns 4A may be symmetrical with the light shielding patterns 2B. The circular coding chip rotates between the optical splitter and the measurement arm and the reference arm, so that the sector where the coding patterns are located is located at a first position between the optical splitter and the measurement arm to block the reference light when the measurement light is coded, or is located at a second position between the optical splitter and the reference arm to block the measurement light when the reference light is coded.

As shown in FIG. 3, the circular coding chip may rotate, so that when time t=0 (that is, an initial time point) , the circular coding chip may code the reference light by means of the coding patterns 4A, and at the same time, may block the measurement light by means of the light shielding patterns 2B; when time t=1, the circular coding chip may code the measurement light by means of the coding patterns 2A, and at the same time, may block the reference light by means of the light shielding patterns 4B; when time t=2, the circular coding chip may code the reference light by means of the coding patterns 3A, and at the same time, may block the measurement light by means of the light shielding patterns 1B; when time t=3, the circular coding chip may code the measurement light by means of the coding patterns 1A, and at the same time, may block the reference light by means of the light shielding patterns 3B; when time t=4, the circular coding chip may code the measurement light by means of the coding patterns 4A, and at the same time, may block the reference light by means of the light shielding patterns 2B; when time t=5, the circular coding chip may code the reference light by means of the coding patterns 2A, and at the same time, may block the measurement light by means of the light shielding patterns 4B; when time t=6, the circular coding chip may code the measurement light by means of the coding patterns 3A, and at the same time, may block the reference light by means of the light shielding patterns 1B; and when time t=7, the circular coding chip may code the reference light by means of the coding patterns 1A, and at the same time, may block the measurement light by means of the light shielding patterns 3B.

In an exemplary embodiment, the circular coding chip shown in FIG. 3 may have a diameter of approximately 5cm to approximately 6cm. The circular coding chip may rotate, so that the circular coding chip may code the measurement light or the reference light for 5 to 6 times in per second. In the exemplary embodiment, the measurement light or the reference light may have a wavelength of 480nm.

In another exemplary embodiment, the coder 300 may include or is implemented as a display. The display may be disposed between the optical splitter and the measurement unit 500, and may display the coding patterns at the first position between the optical splitter and the measurement arm to code the measurement light, or may display the coding patterns at the second position between the optical splitter and the reference arm to code the reference light. Like the foregoing descriptions in the exemplary embodiment in which the coder 300 is implemented as a circular coding chip, the coder 300 implemented as a display may display the light shielding patterns at the second position when the coding patterns are displayed at the first position, so as to block the reference light, or displays blocking patterns at the first position when the coding patterns are displayed at the second position, so as to block the measurement light. Therefore, the display may include a liquid crystal display (LCD) , a digital micro-mirror device (DMD) , and other a plurality of types of display devices. In an example, the coder 300 may include two displays disposed at the first position and the second position respectively.

The

coding patterns

1A, 2A, 3A, and 4A may be different from each other, that is, the positions of the light transmissive part and/or the light shielding part in the

coding patterns

1A, 2A, 3A, and 4A may be different. Therefore, the coder 300 may code one of the measurement light or the reference light in preset time by means of one of the coding patterns different from each other and blocks the other one of the measurement light and the reference light, that is, time division multiplex coding. In other words, the coder 300 may perform coding by using coding patterns whose light transmissive parts have different positions in different time, so that the processor 900 connected to the optical detector 750 may perform decoding by using a time-wavelength mapping algorithm, that is, light intensities in different time points may be recorded to correspond to a wavelength of light received by the optical detector 750 at the time point. Therefore, on the basis that different materials have different light absorption rates for light of different wavelengths; the gas to be measured is analyzed by comparing the light intensity of the measurement light with the light intensity of the reference light coded by the same coding patterns.

In another exemplary embodiment, the coder 300 may code one of the measurement light or the reference light in a preset time period by means of a plurality of coding patterns in the plurality of coding patterns different from each other and blocks the other one of the measurement light and the reference light by means of blocking patterns, that is, frequency division multiplex coding. When the coder 300 is implemented as the circular coding chip shown in FIG. 2, the preset time period may be a time spent after the circular coding chip rotates by one turn. In this way, in each rotation period of the circular coding chip, the measurement light or the reference light is coded by means of different coding patterns, that is, a part of light in the measurement light or the reference light in different positions is allowed to transmissively pass through the coding patterns in each coding, so that the quantities of times of a part of light in the measurement light or the reference light in different positions in each rotation period are different. Therefore, the processor 900 may perform decoding by using a Fourier transform algorithm, that is, components of different frequencies of signals that are received by the optical detector 750 and that correspond to wavelengths of light experiencing to frequency division multiplex coding are recorded as light intensities of corresponding wavelengths, so as to analyze the gas to be measured.

In still another exemplary embodiment, the coding patterns of the coder 300 may be patterns complying with the Welsh-Hadamard algorithm, that is, including patterns for arranging the light transmissive part and the light shielding part according to the Welsh-Hadamard algorithm. The coding patterns 1A, 2A, 3A, and 4A shown in FIG. 2 may be patterns complying with the Welsh-Hadamard algorithm. The coding patterns 1A, 2A, 3A, and 4A may correspond to the following expression:

In other words, the coding patterns of the coder 300 may be generated according to a Hadamard matrix of a specific order (for example, same as a wavelength resolution) , so that the measurement light or the reference light may be coded. In this way, the processor 900 performs decoding according to the Welsh-Hadamard transform algorithm, that is, signals intensities corresponding to different orthogonal bases among signals that are received by the optical detector 750 and that correspond to light coded according to the Welsh-Hadamard transform algorithm, so as to analyze the gas to be measured.

Although descriptions are made in the above with reference to the coder 300 capable of being implemented as the rotatable circular coding chip, the exemplary embodiment is not limited thereto. When the coder 300 is implemented as an LCD, a DMD and other display apparatuses, coding patterns coded according to time division multiplex coding, frequency division multiplex coding and/or the Welsh-Hadamard algorithm may be displayed at one of the first position and the second position between the optical splitter and the measurement unit, and the light shielding patterns are displayed at the other position, to code the measurement light or the reference light.

It should be understood that, although the specification is described based on embodiments, it does not indicate that each embodiment merely includes one independent technical solution, and the narration manner is merely for an explicitness purpose. Persons skilled in the art should take the specification as a whole, and the technical solutions in the embodiments may be properly combined to form other implementations capable of being understood by the technical persons in the art.

The foregoing descriptions are merely specific schematic implementations of the present invention, and are not intended to limit the range of the present invention. Any equivalent changes, modifications and combinations made by any technical persons in the art without departing from ideas and principles of the present invention should fall within the protection scope of the present invention.

Claims

A gas analyzer, comprising:

a light source (110) ;

an optical splitter (150) , dividing light emitted by the light source into measurement light and reference light;

a measurement arm (510) and a reference arm (530) , wherein gas to be measured is filled in the measurement arm, reference gas is filled in the reference arm, the measurement light propagatively passes through the measurement arm, and the reference light propagatively passes through the reference arm;

an optical detector (750) , receiving light propagatively passing through the measurement arm and light propagatively passing through the reference arm, and converting the received light into electrical signals; and

a coder (300) , disposed between the optical splitter and the measurement arm and the reference arm, wherein the coder is configured to code one of the measurement light and the reference light and block the other one of the measurement light and the reference light.
The gas analyzer according to claim 1, comprising:

a grating (130) , disposed between the light source and the optical splitter, wherein the grating (130) is configured to separate the light emitted from the light source into a plurality of beams of light of different wavelengths.
The gas analyzer according to claim 1, comprising a lens unit (710) , an optical coupler (730) , and a position regulator (770) , wherein

the lens unit is configured to guide the light propagatively passing through the measurement arm and the light propagatively passing through the reference arm, to enter the optical coupler,

the optical coupler is configured to guide the light guided by the lens unit, to illuminate the optical detector; and

the position regulator is configured to regulate a position of the optical detector, so that the optical detector is located at a focus of the optical coupler.
The gas analyzer according to claim 1, wherein the coder comprises:

coding patterns, configured to allow at least one part of one of the measurement light or the reference light to transmissively pass through the coding patterns and to be propagated to the measurement arm or the reference arm, to code the beam of light; and

light shielding patterns, configured to block the other one of the measurement light or the reference light from transmissively passing through the light shielding patterns.
The gas analyzer according to claim 4, wherein the coding patterns comprise a plurality of coding patterns different from each other, and the coder is configured to code one of the measurement light or the reference light in preset time by means of one of the plurality of coding patterns different from each other and block the other one of the measurement light and the reference light.
The gas analyzer according to claim 4, wherein the coding patterns comprise a plurality of coding patterns different from each other, and the coder is configured to code one of the measurement light or the reference light in a preset time period by means of a plurality coding patterns in the plurality of coding patterns different from each other and block the other one of the measurement light and the reference light.
The gas analyzer according to claim 4, wherein the coding patterns comprise coding patterns complying with a Welsh-Hadamard algorithm, and the coder is configured to code one of the measurement light or the reference light by means of the coding patterns complying with the Welsh-Hadamard algorithm and block the other one of the measurement light and the reference light.
The gas analyzer according to claim 4, wherein the coder comprises a circular coding chip, and the coding patterns are located on at least one sector of the circular coding chip.
The gas analyzer according to claim 8, wherein the circular coding chip is configured to rotate between the optical splitter and the measurement arm and the reference arm, so that the sector where the coding patterns are located is located at a first position between the optical splitter and the measurement arm to code the measurement light or is located at a second position between the optical splitter and the reference arm to code the reference light.
The gas analyzer according to claim 9, wherein the light shielding patterns are located at a sector of the circular coding chip symmetrical with the sector where the coding patterns are located relative to a circle center of the circular coding chip, so that the sector where the coding patterns are located is located at the first position between the optical splitter and the measurement arm to block the reference light when the measurement light is coded, or the sector where the coding patterns are located is located at the second position between the optical splitter and the measurement arm to block the measurement light when the reference light is coded.
The gas analyzer according to claim 4, wherein the coder comprises a display, wherein the display is configured to display the coding patterns at the first position between the optical splitter and the measurement arm, to code the measurement light, or display the coding patterns at the second position between the optical splitter and the reference arm to code the reference light.
The gas analyzer according to claim 11, wherein the display is configured to, when the coding patterns are displayed at the first position, display the light shielding patterns at the second position to block the reference light, or when the coding patterns are displayed at the second position, display blocking patterns at the first position to block the measurement light.
The gas analyzer according to claim 11, wherein the display comprises at least one of a liquid crystal display and a digital micro-mirror device.
The gas analyzer according to claim 1, comprising:

a processor (900) , configured to receive the electrical signal from the optical detector, and obtain information related to the gas to be measured according to the received electrical signal.
The gas analyzer according to claim 14, wherein the coder comprises coding patterns, and the coding patterns are configured to allow at least one part of one of the measurement light or the reference light to transmissively pass through the coding patterns and to be propagated to the measurement arm or the reference arm, to code the beam of light, and the processor is configured to be capable of performing decoding processing on a received electrical signal corresponding to coded light by using a time-wavelength mapping algorithm, a Fourier transform algorithm and a Welsh-Hadamard transform algorithm.