CN102879376A - Sensor for detecting nitro-aromatics explosives - Google Patents

Abstract

The invention relates to a sensor for detecting nitroaromatic explosives, which comprises a wheel-shaped optical fiber sensor head coupled to the end face of a blue laser, an air chamber, a high-pass filter, and an optical power meter. The wheel-shaped optical fiber sensor head is placed in the air In the chamber, there are gas inlets and outlets on the gas chamber, and the wheel-shaped optical fiber sensor head includes a blue laser, a circulator, and a wheel-shaped optical fiber coated with MEH-PPV sensitive materials by the pulling method from the outside to the inside. After passing through the circulator, the light is coupled into the wheel-shaped optical fiber by the end-face coupling method, and the light in the wheel-shaped optical fiber passes through the circulator and enters the high-pass filter with a cut-off wavelength of 510nm, and then enters the optical power meter. The concentration of explosives is detected by detecting the intensity of the fluorescent indicator, and the detection limit and sensitivity can be increased by 10-20 times compared with similar products. In addition, the sensor has the advantages of fast detection speed, stable working performance, and small required sample volume.

Description

Sensors for the detection of nitroaromatic explosives

technical field

The invention relates to a sensor, in particular to a sensor with a wheel-shaped optical fiber sensor head for detecting nitroaromatic explosives.

Background technique

With the growth of international terrorist forces, extremists have created a series of vicious explosions around the world, which pose a great threat to human survival and safety. Explosives on the body have become a common problem faced by law enforcement agencies in various countries.

The detection technology of explosives can be divided into bulk detection technology and micro-trace detection technology.

Explosive physical detection technology has disadvantages such as high price, low sensitivity, and large equipment volume, so it has limitations in application.

The micro-trace detection technology of explosives is mainly to detect the steam volatilized by explosives and the traces of explosives that adhere to the surface of explosive containers and any objects (including human body) that have been in contact with explosives. technology.

At present, the technologies that can be used to detect micro-trace explosives are mainly various spectral technologies, sensing technologies based on the principle of fluorescence quenching, and biosensing technologies. Spectral detection methods mainly include gas chromatography (GC), mass spectrometry (MS) and ion mobility spectrometry (IMS). At present, these micro-trace detection technologies are still in the process of continuous exploration and development. In terms of development prospects, the fluorescence quenching explosives sensor has the advantages of fast detection speed, high detection sensitivity, good stability, low sensor cost, small size, and easy operation. One of the good techniques.

The core diameter of the wheel-shaped optical fiber is 1.6 microns, surrounded by three air holes with a diameter of 8 microns, and an outer diameter of 125 microns. The advantage of this sensor head is that the fluorescent indicator can be directly coated around the air hole, and the detected nitroaromatic explosive gas can also directly enter the air hole. Due to the effect of the evanescent wave, the fluorescent indicator emits fluorescence. The fluorescence intensity decreases as the concentration of the explosive increases, and the concentration of the explosive is measured by detecting the fluorescence intensity coupled back into the fiber core.

The main technical problem of the current micro-trace explosives sensor based on the principle of fluorescence quenching is that the fluorescence intensity of the fluorescent indicator is weak, which increases the difficulty of detecting the fluorescent signal and reduces the sensitivity and detection limit of the system.

Contents of the invention

The present invention aims at the problem that the current micro-trace explosives sensor based on the principle of fluorescence quenching reduces the detection sensitivity due to the weak fluorescence intensity of the fluorescent indicator, and proposes a sensor for detecting nitroaromatic explosives. The intensity of the indicator will decrease as the concentration of the explosive increases, and the detection sensitivity of the concentration of the explosive by detecting the fluorescence intensity of the fluorescent indicator decreases, but the wheel-shaped optical fiber can increase the intensity of the evanescent wave entering the air hole, Furthermore, the luminous intensity of the fluorescent indicator is increased to achieve the purpose of improving the sensitivity and detection limit of the system, which can well solve the problems existing in this type of sensor at present.

The technical scheme of the present invention is: a sensor for detecting nitroaromatic explosives, including a wheel-shaped optical fiber sensor head coupled to the end face of a blue laser, an air chamber, a high-pass filter, an optical power meter, and a wheel-shaped optical fiber sensor The head is placed in the air chamber, where the wheel-shaped optical fiber sensor head includes a blue laser, a circulator, and a wheel-shaped optical fiber coated with MEH-PPV sensitive materials by the pulling method from the outside to the inside. The light emitted by the blue laser passes through the circulator , using the end-face coupling method to couple into the wheel-shaped optical fiber, and then the light in the wheel-shaped optical fiber enters the high-pass filter with a cut-off wavelength of 510 nm through the circulator and then enters the optical power meter.

The high-pass filter is placed on the optical bench, the probe of the optical power meter and the high-pass filter are on a horizontal line, and the probe of the optical power meter directly detects the light intensity after passing through the high-pass filter.

There are gas inlets and outlets on the gas chamber, which are used for passing explosive gases with different concentrations.

The beneficial effect of the invention is that: compared with similar products, the detection limit and sensitivity of the sensor for detecting nitroaromatic explosives can be increased by 10-20 times. In addition, the sensor has the advantages of fast detection speed, stable working performance, and small required sample volume.

Description of drawings

Fig. 1 is the sensor structure schematic diagram that the present invention is used to detect nitroaromatics explosives;

Fig. 2 is a schematic cross-sectional view of a wheel-shaped optical fiber in a sensor for detecting nitroaromatic explosives according to the present invention.

Detailed ways

As shown in Figure 1, a schematic structural diagram of a sensor for detecting nitroaromatic explosives, including a wheel-shaped optical fiber sensor head coupled with a blue laser end face, an air chamber 4, a high-pass filter 5, an optical power meter 6, and a wheel-shaped optical fiber sensor head The sensing head is placed in the air chamber, and there are gas inlets and outlets on the air chamber 4, as shown in the arrows in the figure, wherein the wheel-shaped optical fiber sensor head coupled with the end face of the blue laser is shown in Figure 2. Blue laser 1, circulator 2, wheel-shaped optical fiber 3 coated with MEH-PPV sensitive material by pulling method.

Preparation of the wheel-shaped optical fiber sensing head: firstly, the sensitive material MEH-PPV was dissolved in chloroform with a concentration of 1 mg/ml. Then place one end of the 30 cm long wheel-shaped optical fiber 3 in the sensitive material and let it stand for 5 minutes. After taking it out, put it in an oven with a temperature of 80 degrees for 100 minutes, and take it out of the oven after the chloroform volatilizes.

After passing through the circulator 2, the light emitted by the blue laser 1 is coupled into the wheel-shaped optical fiber 3 by using an end-face coupling method.

The wheel-shaped optical fiber sensing head is placed in the gas chamber 4, and the gas inlet and outlet on the gas chamber 4 are used to pass explosive gases of different concentrations;

The light in the optical fiber enters the high-pass filter 5 with a cut-off wavelength of 510nm through the circulator 2 and then enters the optical power meter 6 to detect the concentration of explosives by detecting the intensity of the fluorescent indicator. The high-pass filter is placed on the optical bench , the probe of the optical power meter and the high-pass filter are on a horizontal line, and the probe of the optical power meter directly detects the light intensity after passing through the high-pass filter 5 .

Claims (3)

1. A sensor for detecting nitroaromatic explosives is characterized in that it comprises a wheel-shaped optical fiber sensor head, an air chamber, a high-pass filter, an optical power meter, and a wheel-shaped optical fiber sensor head coupled with a blue-light laser Placed in the air chamber, the wheel-shaped optical fiber sensor head includes a blue laser, a circulator, and a wheel-shaped optical fiber coated with MEH-PPV sensitive materials by the pulling method from the outside to the inside. After the light emitted by the blue laser passes through the circulator, The end-face coupling method is used to couple into the wheel-shaped optical fiber, and the light in the wheel-shaped optical fiber passes through the circulator and enters the high-pass filter with a cut-off wavelength of 510nm, and then enters the optical power meter. 2. The sensor for detecting nitroaromatic explosives according to claim 1 is characterized in that, the high-pass filter is placed on the optical bench, and the probe of the optical power meter and the high-pass filter are on a horizontal line Above, the probe of the optical power meter directly detects the light intensity after passing through the high-pass filter. 3. The sensor for detecting nitroaromatic explosives according to claim 1, characterized in that there are gas inlets and outlets on the gas chamber for passing explosive gases of different concentrations.

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