CN218331173U - Very early dual laser smoke detection - Google Patents

Abstract

The utility model provides a two laser smog in very early stage are surveyed relates to the technical field of alarm, and two laser smog in very early stage are surveyed and are included: the detection chamber is internally provided with a detection cavity, detection gas is introduced into the detection cavity, the red laser light source can emit red light beams into the detection cavity, the blue laser light source can emit blue light beams into the detection cavity, and the red light beams and the blue light beams are crossed in the detection cavity and form a first plane; the photocell is connected with the detection cavity, and the receiving surface of the photocell is parallel to the first plane, is positioned below the intersection point of the red light beam and the blue light beam, and is used for receiving smoke scattering light which forms 90 degrees with the axial direction of the red light beam and the blue light beam respectively.

Description

Very early dual laser smoke detection

Technical Field

The utility model belongs to the technical field of the alarm technique and specifically relates to a two laser smog in very early stage are surveyed.

Background

A smoke-sensitive fire detection alarm is generally installed on an indoor ceiling, and when smoke is generated due to indoor fire, the smoke rises and enters the smoke-sensitive fire detection alarm, so that the smoke-sensitive fire detection alarm can be triggered to send out an alarm.

The smoke-sensitive fire detection alarm generally comprises a shell, a light emission component and a light detection component, wherein the light emission component and the light detection component are both arranged in the shell, a diaphragm is arranged on the side wall of the shell, and an effective scattering area exists between the light emission component and the light detection component in the shell. Under the condition of no smog, the light that light emission component transmitted can not be detected by light detection component, and under the condition of smog, the light that enters into in this effective scattering area can meet the smog in this effective scattering area and take place the scattering, and light after the scattering just can shoot light detection component, is detected by light detection component. The higher the concentration of smog, the higher the intensity of the light that light detection components and parts detected is, when the intensity of the light that light detection components and parts detected is greater than the predetermined threshold value, the smoke sensing fire detection alarm just can send the warning.

However, along with the aggravation of environmental pollution, the generation of haze can produce the image to the alarm, and the alarm produces the wrong report fire alarm because of unable discernment dust and smog, especially when haze day or air heavily pollute.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a two laser smog in very early stage are surveyed to alleviate the technical problem that current alarm produced misjudgement easily.

The embodiment of the utility model provides a pair of very early pair of laser smog is surveyed, include: the detection chamber is internally provided with a detection cavity, detection gas is introduced into the detection cavity, the red laser light source can emit red light beams into the detection cavity, the blue laser light source can emit blue light beams into the detection cavity, and the red light beams and the blue light beams are crossed in the detection cavity and form a first plane;

the photocell is connected with the detection cavity, and the receiving surface of the photocell is parallel to the first plane, is positioned below the intersection point of the red light beam and the blue light beam, and is used for receiving smoke scattering light which forms 90 degrees with the axial direction of the red light beam and the axial direction of the blue light beam.

Furthermore, a detection port communicated with the inside and the outside of the detection cavity is formed in the side wall of the detection cavity, the photocell is connected with the outer wall of the detection cavity in a sealing mode, the photocell is opposite to the detection port, and the photocell can receive smoke scattered light.

Further, be provided with the intercommunication on the lateral wall of detection cavity detect the inside and outside main air inlet and the main gas outlet of cavity, main air inlet and main gas outlet are located the both sides of detecting the mouth, main air inlet is used for letting in the testing gas, main gas outlet is used for discharging the testing gas.

Further, the red light laser light source and the blue light laser light source are respectively connected to the left side and the right side of the detection chamber;

light inlet cavities are arranged between the red light laser light source and the detection chamber and between the blue light laser light source and the detection chamber;

a first incident hole and a first exit hole which are communicated with the inside and the outside of the light incident cavity and are arranged on the same linear path are formed in the side wall of the light incident cavity, and the first exit hole is used for enabling the light beam to enter the detection cavity; the light outlets of the red light laser light source and the blue light laser light source are opposite to the first light inlet holes of the corresponding light inlet cavities.

Furthermore, an isolation cavity is arranged between the light inlet cavity and the detection cavity;

the first exit hole is communicated with the light inlet cavity and the isolation cavity; an auxiliary air inlet and a second exit hole which are communicated with the inside and the outside of the isolation cavity are formed in the side wall of the isolation cavity, and the auxiliary air inlet is used for introducing protective gas; the second emergent hole is communicated with the isolation cavity and the detection cavity;

the first exit hole and the second exit hole are on the same straight path.

Furthermore, the inner walls of the light incident cavity and the isolation cavity are provided with frosted structures for reducing stray light.

Furthermore, the detection chamber also comprises two extinction cavities which are respectively positioned at two sides of the detection cavity;

the extinction cavity is communicated with the detection cavity through a third emergent hole, and the third emergent hole and the second emergent hole are on the same straight path;

and a light absorption structure is arranged on the inner wall of the extinction cavity and used for preventing laser from being emitted from the extinction cavity.

Furthermore, the light absorption structure comprises a smooth surface positioned on an optical axis of the light beam, an incident angle of the light beam on the smooth surface is larger than 90 degrees, and light absorption protrusions are densely distributed on the inner wall of the extinction cavity.

Further, the very early double-laser smoke detection device comprises an air duct, a fan and a filter chamber, wherein the air duct comprises an air inlet, an air outlet and an air guide channel communicated with the air inlet and the air outlet, and the fan is positioned in the air guide channel;

a first flow guide port communicated with the main air outlet is formed in the side wall of the air guide channel, and the first flow guide port is positioned between the fan and the air inlet;

a second flow guide port communicated with the filter chamber is formed in the side wall of the air guide channel, and the second flow guide port is positioned between the fan and the air outlet;

the filter chamber comprises a filter chamber body, a first exhaust port and two second exhaust ports are arranged on the filter chamber body, the first exhaust port is connected with the main air inlet, and the second exhaust port is connected with the auxiliary air inlet;

the filter chamber is internally provided with a first filter filler positioned between the first exhaust port and the second diversion port, the filter chamber is internally provided with a second filter filler positioned between the second exhaust port and the second diversion port, the first filter filler is used for filtering suspended particles in the air, and the second filter filler is used for filtering impurities in the air.

Furthermore, the air duct includes two air inlet channels arranged at intervals, each air inlet channel is provided with one air inlet, outlets of the two air inlet channels face the fan, and the first diversion port is located between the two air inlet channels;

an annular sealing edge extending inwards is arranged at one port of the air duct, the inner edge of the sealing edge is connected with a guide pipe coaxial with the air duct, one part of the guide pipe extends into the air duct, one part of the guide pipe is positioned outside the air duct, the part positioned in the air duct is provided with a guide section, and the inner diameter of the guide section is gradually increased from the inside to the outside of the air duct;

the second diversion port is located on the side of the guide section.

The embodiment of the utility model provides an extremely early pair of laser smog is surveyed and is included: the detection chamber is internally provided with a detection cavity, detection gas is introduced into the detection cavity, the red laser light source can emit red light beams into the detection cavity, the blue laser light source can emit blue light beams into the detection cavity, and the red light beams and the blue light beams are crossed in the detection cavity and form a first plane; the photocell is connected with the detection cavity, and the receiving surface of the photocell is parallel to the first plane, is positioned below the intersection point of the red light beam and the blue light beam, and is used for receiving smoke scattering light which forms 90 degrees with the axial direction of the red light beam and the axial direction of the blue light beam. When the double-laser smoke detection works in the very early stage, the red laser light source and the blue laser light source work alternately, for example, the red laser light source is started to emit a red light beam, the red light beam enters the detection cavity and then acts with the detection gas, the photocell receives scattered light of smoke at a scattered light receiving angle of 90 degrees, the detection sensitivity can be improved, converted electric signals are sent to the processor for processing through photoelectric conversion, then the red laser is turned off, the blue laser light source is started to emit a blue light beam, the red light beam enters the detection cavity and then acts with the detection gas, the photocell receives scattered light of smoke at a scattered light receiving angle of 90 degrees, the detection sensitivity can be improved, and the converted electric signals are sent to the processor for processing through photoelectric conversion; the red laser wavelength is 650nm, the blue laser wavelength is 405nm, the generated smoke particles are different under the fire conditions of different applications and materials, and the actual smoke concentration is detected more sensitively and accurately through the response difference of the two different wavelengths to the smoke particles.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following descriptions are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic diagram of an internal structure of a very early dual-laser smoke detection provided by an embodiment of the present invention;

fig. 2 is a schematic view of an internal structure of a detection chamber for very early dual-laser smoke detection according to an embodiment of the present invention;

fig. 3 is a schematic diagram of very early dual-laser smoke detection provided by an embodiment of the present invention;

fig. 4 is a top view of a very early dual laser smoke detection provided by an embodiment of the present invention;

FIG. 5 isbase:Sub>A cross-sectional view taken along line A-A of FIG. 4;

FIG. 6 is a cross-sectional view taken along line B-B of FIG. 4;

fig. 7 is a sectional view taken along the direction C-C in fig. 4.

Icon: 100-a housing; 110-a via;

200-a detection chamber; 210-a light incident cavity; 211-a first entry hole; 212-first exit aperture;

220-an isolation chamber; 221-secondary air intake; 222-a second exit aperture;

230-a detection cavity; 231-primary air intake; 232-main outlet; 233-detection port;

240-extinction cavity; 241-a third exit aperture; 242-smooth surface; 243-light absorbing protrusions;

310-red laser light source; 320-blue laser light source;

400-a photovoltaic cell;

500-air duct; 510-an air inlet; 520-an air outlet; 530-a first diversion port; 540-a second flow guide port; 550-air inlet channel; 560-a conduit;

600-a fan;

700-filtering chamber; 710-a first exhaust port; 720-first filter packing; 730-a second exhaust port; 740-second filter packing.

Detailed Description

The technical solution of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

As shown in fig. 1-7, the embodiment of the present invention provides an extremely early stage dual laser smoke detection method, which includes: the detection device comprises a detection chamber 200, a red light laser light source 310, a blue light laser light source 320 and a photocell 400, wherein the detection chamber 200 is internally provided with a detection cavity 230, detection gas is introduced into the detection cavity 230, the red light laser light source 310 can emit a red light beam into the detection cavity 230, the blue light laser light source 320 can emit a blue light beam into the detection cavity 230, and the red light beam and the blue light beam are crossed in the detection cavity 230 and form a first plane; the photocell 400 is connected with the detection cavity 230, and a receiving surface of the photocell 400 is parallel to the first plane and is located below an intersection point of the red light beam and the blue light beam, and is used for receiving smoke scattering light which forms 90 degrees with the axial direction of the red light beam and the blue light beam respectively.

During the very early stage of double-laser smoke detection, the red laser light source 310 and the blue laser light source 320 alternately operate, for example, the red laser light source 310 is started to emit a laser red light beam with a frequency of 200 red light beams and a time duration of 1 second, the red light beam enters the detection cavity 230 and then acts with a detection gas, the photocell 400 receives scattered light of smoke at a scattered light receiving angle of 90 degrees, the detection sensitivity can be improved, the converted electric signal is sent to the processor for processing through photoelectric conversion, then the red laser is turned off, the blue laser light source 320 is started to emit a laser blue light beam with a frequency of 200 red light beams and a time duration of 1 second, the red light beam enters the detection cavity 230 and then acts with the detection gas, the photocell 400 receives scattered light of smoke at a scattered light receiving angle of 90 degrees, the detection sensitivity can be improved, and the converted electric signal is sent to the processor for processing through photoelectric conversion; the red laser wavelength is 650nm, the blue laser wavelength is 405nm, the actual smoke concentration value can be obtained through the response difference of the two different wavelengths to smoke and dust, and the influence of haze is avoided.

The side wall of the detection cavity 230 is provided with a detection port 233 communicated with the inside and the outside of the detection cavity 230, the photocell 400 is hermetically connected with the outer wall of the detection cavity 230, so that the detection gas is prevented from flowing out of the detection port 233, the photocell 400 is opposite to the detection port 233, and the photocell 400 can receive smoke scattering light.

The side wall of the detection cavity 230 is provided with a main air inlet 231 and a main air outlet 232 which are communicated with the inside and the outside of the detection cavity 230, the main air inlet 231 and the main air outlet 232 are positioned at two sides of the detection port 233, so that the detection gas is fully contacted with the light beam, the main air inlet 231 is used for introducing the detection gas, and the main air outlet 232 is used for discharging the detection gas.

The red laser light source 310 and the blue laser light source 320 are respectively connected to the left and right sides of the detection chamber 200. Light inlet cavities 210 are arranged between the red light laser light source 310 and the detection chamber 200 and between the blue light laser light source 320 and the detection chamber 200; a first incident hole 211 and a first exit hole 212 which are communicated with the inside and the outside of the light incident cavity 210 and are on the same straight path are arranged on the side wall of the light incident cavity 210, and the first exit hole 212 is used for enabling a light beam to enter the detection cavity 230; the light outlets of the red light laser source 310 and the blue light laser source 320 are opposite to the first light inlet hole 211 of the light inlet cavity 210 corresponding thereto.

The red light laser light source 310 and the blue light laser light source 320 are symmetrically arranged, and the working environments of the red light laser light source 310 and the blue light laser light source 320 are also symmetrical, in this embodiment, the red light laser light source 310 is taken as an example for description, and a first incident hole 211 and a first exit hole 212 which communicate the inside and the outside of the light incident cavity 210 are arranged on the side wall of the light incident cavity 210; the red light laser source 310 is hermetically connected with the outer wall of the light inlet cavity 210, and a light outlet of the red light laser source 310 faces the first light inlet hole 211. The first incident hole 211 is sealed by the red laser source 310, so only the first exit hole 212 on the light cavity 210 is connected to the outside.

An isolation cavity 220 is arranged between the light inlet cavity 210 and the detection cavity 230; the first exit hole 212 communicates with the light incident cavity 210 and the isolation cavity 220; the side wall of the isolation cavity 220 is provided with an auxiliary gas inlet 221 and a second exit hole 222 which are communicated with the inside and the outside of the isolation cavity 220, and the auxiliary gas inlet 221 is used for introducing protective gas; the second exit hole 222 communicates with the isolation cavity 220 and the detection cavity 230; the first exit aperture 212 and the second exit aperture 222 are on the same straight line path.

The isolation cavity 220 is located at one side of the light incident cavity 210, and the first exit hole 212 communicates with the light incident cavity 210 and the isolation cavity 220. The side wall of the isolation cavity 220 is provided with an auxiliary gas inlet 221 and a second exit hole 222 which are communicated with the inside and the outside of the isolation cavity 220, and the auxiliary gas inlet 221 is used for introducing protective gas. In this embodiment, the shielding gas in the isolation cavity 220 enters from the secondary gas inlet 221 and flows out from the second exit hole 222, the second exit hole 222 communicates with the isolation cavity 220 and the detection cavity 230, and the introduction of the shielding gas prevents the gas flow in the detection cavity 230 from entering the isolation cavity 220 from the second exit hole 222.

The first incident hole 211, the first exit hole 212 and the second exit hole 222 are all on the optical axis of the light beam. The diameters of the first exit hole 212 and the second exit hole 222 are small and are matched with the beam diameter to form a diaphragm structure, so that stray light of laser can be reduced.

The inner walls of the light-incident cavity 210 and the isolation cavity 220 have frosted structures, so that stray light is reduced, and the detection precision of the photocell 400 is improved.

The detection chamber 200 further comprises two extinction cavities 240, and the two extinction cavities 240 are respectively located at two sides of the detection cavity 230; the extinction cavity 240 is communicated with the detection cavity 230 through a third exit hole 241, and the third exit hole 241 and the second exit hole 222 are on the same straight line path; the inner wall of the extinction cavity 240 is provided with a light absorption structure for preventing laser from being emitted from the extinction cavity 240.

The light-incident cavity 210, the isolation cavity 220, the detection cavity 230 and the extinction cavity 240 are sequentially arranged along the emitting direction of the laser, and in order to avoid the reflected light of the laser from affecting the detection result of the photocell 400, a light-absorbing structure is arranged in the extinction cavity 240, so that the laser can be completely absorbed when entering the extinction cavity 240.

The light absorbing structure comprises a light surface 242 positioned on the optical axis of the light beam, the incident angle of the light beam on the light surface 242 is larger than 90 degrees, and light absorbing protrusions 243 are densely distributed on the inner wall of the light extinction cavity 240. The laser entering the light extinction cavity 240 from the detection cavity 230 first contacts the light surface 242, the light surface 242 reflects the laser to the light absorption protrusion 243 on the light extinction cavity 240, and the laser can be absorbed after multiple reflections in the light extinction cavity 240.

The ultra-early double-laser smoke detection device comprises an air duct 500, a fan 600 and a filter chamber 700, wherein the air duct 500 comprises an air inlet 510, an air outlet 520 and an air guide channel communicated with the air inlet 510 and the air outlet 520, and the fan 600 is located in the air guide channel. After the fan 600 is started, airflow can be generated in the air guide channel, so that external air flows out from the air inlet 510 and then flows out from the air outlet 520.

A first diversion port 530 communicated with the main air outlet 232 is arranged on the side wall of the air guide channel, and the first diversion port 530 is positioned between the fan 600 and the air inlet 510. A second diversion opening 540 communicated with the filtering chamber 700 is arranged on the side wall of the air guide channel, and the second diversion opening 540 is positioned between the fan 600 and the air outlet 520. The air in the air duct 500 can enter the filter chamber 700 through the second diversion opening 540 under the action of pressure, the filter chamber 700 filters the air to a certain extent, then the air is introduced into the detection chamber 200, and the air detected in the detection chamber 200 flows out through the second diversion opening 540.

The filtering chamber 700 comprises a filtering chamber body, the filtering chamber body is provided with a first exhaust port 710 and a second exhaust port 730, the first exhaust port 710 is connected with the primary air inlet 231, and the second exhaust port 730 is connected with the secondary air inlet 221. The first filtering filler 720 located between the first exhaust port 710 and the second diversion port 540 is arranged in the filtering cavity, the second filtering filler 740 located between the second exhaust port 730 and the second diversion port 540 is arranged in the filtering cavity, the first filtering filler 720 is used for filtering suspended particles in the air, and the second filtering filler 740 is used for filtering impurities in the air. The filtering capacity of the second filtering filler 740 is much stronger than that of the first filtering filler 720, the first filtering filler 720 may be a common sponge, the second filtering filler 740 may be a high-density sponge, the second filtering filler 740 is configured to generate a protective gas to protect the laser light source, and the first filtering filler 720 is configured to prevent the detection chamber 200 from having too many particle impurities to reduce the service life. Specifically, the number of the second exhaust ports 730 on the filtering cavity is two, the filtering cavity is divided into three parts by ribs, the first filtering filler 720 is located in the middle, the number of the second filtering fillers 740 is two, and the two second filtering fillers 740 are located on two sides of the first filtering filler 720 and correspond to the two isolation cavities 220.

The air duct 500 includes two air inlet channels 550 disposed at intervals, each air inlet channel 550 has one air inlet 510, outlets of the two air inlet channels 550 face the fan 600, and the first diversion port 530 is located between the two air inlet channels 550. After the blower 600 is started, the external air enters from the two air inlet channels 550, and the first diversion opening 530 is located between the two air inlet channels 550, so as to avoid the air flow of the air inlet channels 550 from impressing the outflow of the air flow at the first diversion opening 530.

An annular sealing edge extending inwards is arranged at one port of the air duct 500, the inner edge of the sealing edge is connected with a guide pipe 560 coaxial with the air duct 500, one part of the guide pipe 560 extends into the air duct 500, one part of the guide pipe is positioned outside the air duct 500, the part positioned in the air duct 500 is provided with a guide section, and the inner diameter of the guide section is gradually increased from the inside to the outside of the air duct 500; the second diversion opening 540 is located at the side of the guide section. The air duct 500 is configured to divide the air flow flowing from top to bottom into two parts, one part flows out from the duct 560 and is discharged from the inside of the air duct 500, the other part enters the side of the duct 560 and then enters the second diversion port 540, and the guide section is configured at the end of the duct 560 to guide the air flow to the circumferential outer side of the duct 560, so that the resistance of the air flow entering the second diversion port 540 can be reduced.

The alarm includes casing 100, detection mechanism is located inside casing 100, casing 100 play the guard action, be provided with the through-hole 110 who aligns with air intake 510 and air outlet 520 on the casing 100 to improve the smoothness nature that the gas flows.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims (10)

1. An extremely early dual laser smoke detection, comprising: the detection device comprises a detection chamber (200), a red light laser light source (310), a blue light laser light source (320) and a photocell (400), wherein a detection cavity (230) is arranged in the detection chamber (200), detection gas is communicated in the detection cavity (230), the red light laser light source (310) can emit a red light beam into the detection cavity (230), the blue light laser light source (320) can emit a blue light beam into the detection cavity (230), and the red light beam and the blue light beam are crossed in the detection cavity (230) and form a first plane;

the photocell (400) is connected with the detection cavity (230), and the receiving surface of the photocell (400) is parallel to the first plane, is positioned below the intersection point of the red light beam and the blue light beam, and is used for receiving smoke scattered light which forms 90 degrees with the axial direction of the red light beam and the blue light beam respectively.

2. The very early stage dual laser smoke detection according to claim 1, wherein said detection cavity (230) has a detection port (233) formed in a side wall thereof for communicating the inside and outside of said detection cavity (230), said photocell (400) is hermetically connected to an outer wall of said detection cavity (230), said photocell (400) faces said detection port (233), and said photocell (400) is capable of receiving scattered light of smoke.

3. The very early stage dual laser smoke detection according to claim 2, wherein a main gas inlet (231) and a main gas outlet (232) are arranged on the side wall of the detection chamber (230) and communicate the inside and outside of the detection chamber (230), the main gas inlet (231) and the main gas outlet (232) are located at two sides of the detection port (233), the main gas inlet (231) is used for introducing detection gas, and the main gas outlet (232) is used for discharging detection gas.

4. Very early twin laser smoke detection as per claim 3, where said red (310) and blue (320) laser light sources are connected to the left and right side of the detection chamber (200) respectively;

light inlet cavities (210) are arranged between the red light laser light source (310) and the detection chamber (200) and between the blue light laser light source (320) and the detection chamber (200);

a first incident hole (211) and a first exit hole (212) which are communicated with the inside and the outside of the light incident cavity (210) and are on the same straight line path are formed in the side wall of the light incident cavity (210), and the first exit hole (212) is used for enabling the light beam to enter the detection cavity (230); the light outlets of the red light laser light source (310) and the blue light laser light source (320) are opposite to the first light inlet hole (211) of the corresponding light inlet cavity (210).

5. The very early twin laser smoke detection according to claim 4, wherein an isolation cavity (220) is provided between said entrance cavity (210) and detection cavity (230);

the first exit hole (212) is communicated with the light inlet cavity (210) and the isolation cavity (220); an auxiliary air inlet (221) and a second exit hole (222) which are communicated with the inside and the outside of the isolation cavity (220) are formed in the side wall of the isolation cavity (220), and the auxiliary air inlet (221) is used for introducing protective gas; the second exit hole (222) is communicated with the isolation cavity (220) and the detection cavity (230);

the first exit aperture (212) and the second exit aperture (222) are on the same linear path.

6. The very early dual laser smoke detection system of claim 5, wherein the inner walls of said light-entrance cavity (210) and said isolation cavity (220) have frosted structures for reducing stray light.

7. The very early twin laser smoke detection according to claim 5, wherein said detection chamber (200) further comprises two extinction cavities (240), the two extinction cavities (240) being located on either side of the detection cavity (230);

the extinction cavity (240) is communicated with the detection cavity (230) through a third exit hole (241), and the third exit hole (241) and the second exit hole (222) are on the same straight line path;

and a light absorption structure is arranged on the inner wall of the extinction cavity (240) and used for preventing laser from being emitted from the extinction cavity (240).

8. The very early dual laser smoke detection according to claim 7, wherein said light absorbing structure comprises a smooth surface (242) on the optical axis of the light beam, the angle of incidence of said light beam on the smooth surface (242) being greater than 90 °, and light absorbing protrusions (243) being densely distributed on the inner wall of said extinction cavity (240).

9. The very early stage dual laser smoke detection system of claim 5, wherein said very early stage dual laser smoke detection system comprises an air duct (500), a blower (600) and a filter chamber (700), said air duct (500) comprising an air inlet (510), an air outlet (520) and an air guiding channel communicating said air inlet (510) and said air outlet (520), said blower (600) being located within said air guiding channel;

a first flow guide opening (530) communicated with the main air outlet (232) is formed in the side wall of the air guide channel, and the first flow guide opening (530) is located between the fan (600) and the air inlet (510);

a second flow guide opening (540) communicated with the filter chamber (700) is formed in the side wall of the air guide channel, and the second flow guide opening (540) is located between the fan (600) and the air outlet (520);

the filter chamber (700) comprises a filter chamber body, a first exhaust port (710) and two second exhaust ports (730) are arranged on the filter chamber body, the first exhaust port (710) is connected with the main air inlet (231), and the second exhaust port (730) is connected with the auxiliary air inlet (221);

the filter chamber is internally provided with a first filter filler (720) positioned between the first exhaust port (710) and the second diversion port (540), the filter chamber is internally provided with a second filter filler (740) positioned between the second exhaust port (730) and the second diversion port (540), the first filter filler (720) is used for filtering suspended particles in the air, and the second filter filler (740) is used for filtering impurities in the air.

10. The very early stage dual laser smoke detection system of claim 9, wherein said air duct (500) comprises two air inlet channels (550) spaced apart from each other, each air inlet channel (550) having one of said air inlets (510), the outlets of both air inlet channels (550) facing the fan (600), said first diversion port (530) being located between the two air inlet channels (550);

an annular sealing edge extending inwards is arranged at one port of the air duct (500), the inner edge of the sealing edge is connected with a guide pipe (560) coaxial with the air duct (500), one part of the guide pipe (560) extends into the air duct (500), one part of the guide pipe is positioned outside the air duct (500), the part positioned inside the air duct (500) is provided with a guide section, and the inner diameter of the guide section is gradually increased from the inside to the outside of the air duct (500);

the second diversion port (540) is located on the side of the guide section.

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