RU2388026C2 - Method of making signalling devices - Google Patents

Abstract

FIELD: physics, signalling.

SUBSTANCE: invention relates to making alarm signals and devices for indicating overshoot of given deformation limits of the surface of monitored objects. The method of making signalling devices which are triggered by interruption of light flux during deformation of the surface of a monitored object includes an emitter which is optically connected through a flexible linear optical guide with a photodetector, and involves making and assembling the said components on the surface of the monitored object. After making the flexible glass optical guide with polished lateral surfaces, a thin light-reflecting layer is deposited on the said lateral surfaces and the glass of the optical guide is subjected to radiation toning with electromagnetic X-ray or gamma-radiation with dose of up to 10 kGy. The optical guide is then rigidly attached to the surface of the monitored object and a beam of fine-focused pulsed or continuous laser radiation with focal distance several times larger than the wavelength of the optical guide is transmitted through the optical guide. Wavelength of the laser radiation corresponds to the transparency range of the glass and the laser radiation has energy of up to 50 mJ. The radiation is transmitted for 60 s, which is sufficient for formation of a narrow channel in the glass on the entire length of the optical guide. During formation of the channel, transparency of the glass along the axis of propagation of the processing laser radiation is restored.

EFFECT: increased reliability of operation of signalling devices made using the proposed method.

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Description

The present invention relates to the field of manufacturing alarm devices and devices for indicating the excess of predetermined surface deformation limits of controlled objects and can be used in the manufacture of security and alarm devices for detecting surface deformation of tanks, boilers, pipelines, cases, shells, supports, beams, plates ceilings, walls, pylons, cornices, racks, stops, awnings and other elements of the supporting structures of various building, heat and power x, etc. objects when exposed to both external and internal forces, as well as to prevent theft from breaking into the walls and partitions of cabinets, drawers, safes, bodies, doors and other protected objects when they are mechanically exposed.

A known method of manufacturing photovoltaic alarm devices [1], triggered by interruption of the light flux within the boundaries of the controlled area and containing optically coupled to each other, mounted on two separate racks light emitters and photodetectors, including their manufacture and installation of racks rigidly on the surface of the object. When the surface of the object is deformed, the racks deviate from the normal position, as a result of which the light rays from the emitters do not fall on the photosensitive elements of the photodetectors, which causes the alarm device to trigger.

Devices made to implement this method do not have high reliability when used to indicate the deformation of the surface of controlled objects, since there is the possibility of false triggering of devices when an external obstacle (dust, fog, smoke, fallen objects, etc.) appears in the path of light rays, or, conversely, the low reliability of the functioning of the devices is manifested when the external (accidental or intentional) glare of the photodetectors with lateral bright light.

In addition, there is a known method of manufacturing optical signaling sensors [2], triggered due to interruption of the light flux within the boundaries of the controlled area of the object and containing optically coupled emitter (light source) and photodetector (photoresistor), between which is located in the optical channel rigidly fixed on a controlled surface (on a bimetallic plate) curtain. When the surface of the object is deformed (when the plate is bent by internal forces due to an increase in the ambient temperature), the shutter blocks the light flux in the optical channel between the emitter and the photodetector, as a result of which the signal device is triggered.

In the production of signaling devices according to this method, the emitter, photodetector and curtain are mounted on the object, and the curtain is mounted rigidly on the controlled surface, and the emitter and photodetector are not rigidly connected to the controlled surface and must remain stationary when the surface of the object is deformed.

The devices manufactured by this method also do not have high operational reliability when used to indicate the surface deformation of controlled objects, since the alarm devices are triggered only when the controlled surface deforms, causing the curtain to shift toward the axis of the optical channel. In addition, such devices are insensitive to small deformations, since for the triggering of the signal device, the linear displacement of the curtain as a result of surface deformation should be so large as to lead to complete shuttering of the optical channel by the curtain.

Closest to the technical nature of the proposed is a method of manufacturing a device for measuring strain [3], which contain an emitter (a source of monochromatic light) and a photodetector (lens), optically coupled by two fibers. In the production of signaling devices using this method, an emitter, a photodetector and two optical fibers are manufactured, which are then mounted on a controlled object, one of the optical fibers being rigidly connected to the controlled object (sample of the material under study).

Devices made by this method do not have high reliability when used to indicate the surface deformation of controlled objects. So, for example, setting up the measuring circuit involves accurate alignment of the device through the selection of the location of the optical fibers near the lens using micrometric mechanisms for moving the optical fibers (while high-precision mechanisms are an integral part of the measuring device). This is necessary to ensure the arrival of light waves on the lens in antiphase. Such a setup is required to establish the difference in the path of the rays along the optical fibers equal to the odd number of half-waves of monochromatic light radiation (i.e., actually the necessary mutual displacements of the optical fibers are carried out within a micrometer (one micron)). Such a small and accurate displacement of the optical fibers makes it possible to fix the initial intensity of the total light flux entering the lens at a zero value.

However, it is known [4] that the complex mechanisms of precise manual tuning are not characterized by high reliability of operation under various external influences. In addition, the devices manufactured by this method provide the ability to detect and measure only longitudinal deformation, which causes the elongation of the fiber rigidly fixed in the material, and practically does not indicate transverse (bending) deformation of the surface of the object, which does not cause the elongation of the fiber. All this characterizes the low reliability of the operation of signal devices manufactured by a known method.

The task of the invention is to increase the reliability of the operation of signaling devices.

The problem is solved in that in the method of manufacturing the signal devices triggered due to interruption of the light flux during deformation of the surface of the controlled object, including the manufacture of an emitter optically coupled through a flexible linear optical fiber with a photodetector of radiation, and their installation on the surface of the controlled object, after manufacturing a flexible a glass fiber with polished side surfaces, a thin reflective layer is applied to them and the glass of the fiber is exposed to radiation tinting Electromagnetic x-ray or gamma radiation dose of up to 10 kGy. Next, a fiber is rigidly fixed on the surface of the object being monitored and a beam of sharply focused pulsed or continuous laser radiation with a focal length many times greater than the fiber length is transmitted through it with a laser wavelength corresponding to the transparency range of the glass and an energy of up to 50 mJ for a period of time up to 60 c, sufficient for the formation of a narrow channel in the glass fiber along the entire length of the fiber, and during channel formation, transparency is restored glass along the axis of propagation of laser processing radiation. Then, a source of narrowly directed light pulsed or continuous radiation of low intensity is connected to the fiber input at an angle to the longitudinal axis of the fiber with a wavelength corresponding to the wavelength of the laser processing radiation.

The invention is illustrated by drawings:

figure 1 - diagram of the formation of the reflected (transparent) channel in the radiation-tinted straight glass fiber during laser processing of the fiber along the axial line (exposure mode of the laser processing radiation);

figure 2 - response circuit of the signal device during deformation (bending) of the controlled surface, causing the signal beam to refract at the interface between the radiation-tinted and transparent regions of the glass fiber and, as a result, leading to accelerated attenuation of the light signal beam in the radiation-tinted part of the fiber ( signal transmission mode);

figure 3 - refraction diagram of the signal beam at the interface of the radiation-tinted and transparent regions of the glass fiber (transmission mode of signal radiation);

4 is a diagram of the formation of a multiply kinked illuminated (transparent) channel of increased length in a radiation-tinted glass fiber with mirror side surfaces during its laser processing (exposure mode of the laser processing radiation);

5 is a diagram of the formation of the reflected (transparent) channel in a radiation-tinted glass fiber with mirrored side surfaces, repeating the shape of the surface of the controlled object (exposure mode of the laser processing radiation).

The drawings indicate: 1 - technological laser (laser processing radiation source); 2 - a beam of laser processing radiation; 3 - radiation-tinted (darkened) glass fiber; 4 - the reflected (transparent) channel of the glass fiber; 5 - the interface between the radiation-tinted and transparent regions of the glass fiber; 6 - surface of the controlled object; 7 - glue; 8 - emitter (signal radiation source); 9 - a beam of signal radiation; 10 - decaying beam of signal radiation: 11 - photodetector of signal radiation; 12 - signal amplifier of the photodetector; 13 - node signal processing amplifier and issuing an alarm; 14 - angle ά of incidence of signal radiation at the interface of the radiation-tinted and transparent regions of the glass fiber; 15 - angle β of refraction of signal radiation at the interface between the radiation-tinted and transparent regions of the glass fiber; 16 - reflective (mirror) layer; 17 - the longitudinal axis of the fiber (normal to its end surface); 18 - angle γ of incidence of the light beam (laser processing or signal radiation) on the end surface of the glass fiber; 19 - angle δ of incidence of the light beam (laser processing or signal radiation) on the reflective (mirror) side surface of the glass fiber; 20 - angle φ of reflection of the light beam (laser processing or signal radiation) from the mirror surface of the reflective layer; 21 is an optical communication line of a laser processing or signal radiation source with an input of a glass fiber (for example, a fiber optic communication line).

The order of operations of the proposed method for the manufacture of signal devices is as follows (see additionally figure 1 ... figure 5):

1) An emitter 8, a photodetector 11, an amplifier 12, an alarm processing and issuing unit 13, and a glass fiber 3 (for example, from borosilicate glass [5, p. 12]) with polished side surfaces having flexibility properties [5, p.24 ... 25, fig. 4].

2) Apply a thin reflective (mirror) layer 16, for example, metal, on the side surfaces of the fiber, using the technology of thin films with a thickness of not more than 12 microns [6, p.176].

3) The glass of the fiber is exposed to radiation tinting by electromagnetic x-ray or gamma radiation with a dose of up to 10 kGy [7, p.273; 8, p. 37].

In this case, the darkening of glass 3 occurs (the glass acquires a golden brown hue) and the optical density (refractive index) of radiation-tinted glass 3 increases (for example, to a value of nton = 1.52 compared to the refractive index of transparent glass npr = 1.50) [7, p. 273, p. 279, fig. 82, p. 282, pl. 248, pl. 249, p. 283, pl. 252; 8, p. 41; 9].

4) Fix (mount) the fiber rigidly on a given surface area of the controlled object 6, for example, using special glue 7. There are other ways of hard mounting the fiber on the controlled surface 6, for example, mechanical.

5) Connect to the input of the fiber a source 1 of sharply focused pulsed or continuous laser processing radiation 2 (the focal length of the output lens of the source 1 must be many times the length of the fiber 3).

The wavelength of the laser processing radiation 2 should be less than 2.5 μm, i.e. correspond to the transparency range of glass (5, p. 9, fig. 1, p. 10]. For example, be equal to: 1.06 microns (solid-state laser - neodymium in the glass); 0.53 ... 0.55 microns (activators - rare-earth elements) :, 0.69 μm (ruby); 0.85 μm (semiconductor laser) [10, p. 27 ... 28, p. 160, pl. 25; 11, p. 39, pl. 4]).

The energy of the processing radiation is up to 50 mJ [110, p.305 ... 313].

The angle 18 of incidence of the laser processing radiation on the end surface of the optical fiber 3 (see Fig. 4) should provide refraction of the beam at an angle less than the limit [12, p.305].

In figures 1, 2 and 5, the angle 18 (incidence of the beam on the end surface of the glass fiber) γ = 0, i.e. the beam propagates normal to the end surface.

6) A beam 2 of pulsed or continuous laser processing radiation is passed through a glass radiation-tinted optical fiber 3 for a period of time up to 60 s.

The time of laser processing of the fiber is determined by the duration of the formation in the glass of a narrow, illuminated [7, p. 373] channel 4 along the entire length of the fiber 3. As a result of laser processing, the transparency of the glass is restored [8, p. 38; 12].

When forming the illuminated channel 4 in the radiation-tinted glass fiber 3 (see Fig. 1), the transparency of the glass is restored along the propagation axis of the laser radiation 2. The diameter of the formed transparent channel 4 is determined by the beam diameter of the laser processing radiation 2 in accordance with the Gaussian law of the distribution of radiation power in the cross section of the light beam, and the boundary 5 of the section of radiation-tinted 3 and transparent 4 regions of the fiber has a distinct character [8; 9].

7) Mount the remaining parts of the alarm device on the surface of the controlled object 6.

When this is connected to the input of the optical fiber 3, previously mounted on the surface of the controlled object 6 (see p. 4), the source 8 of light pulsed or continuous signal radiation 9 of low intensity.

As the emitter 8 is used, for example, a small-sized semiconductor laser (similar, for example, used in laser pointers [10, p. 318 ... 320]) or a source based on light-emitting diodes [13, p. 10 ... 15, table 2.1]) . The emitter 8 is connected to the input of the fiber 3 at the same angle γ to the longitudinal axis as in the laser processing (reflection) of the glass. In this case, the wavelength of the signal radiation 9 should correspond to the wavelength of the laser processing radiation 2 used (see clause 5 and clause 6) for processing (illuminating) glass. A photodetector 11 is connected to the output of the fiber, connected through an amplifier 12 to the processing unit and issuing an alarm 13. An alarm is generated in case of interruption (disappearance) of the light flux of the signal radiation 9 in the fiber 3.

The principle of operation of the signal device manufactured by the proposed method is as follows (see figure 2 and 3).

Until the controlled surface 6 is bent, the signal radiation 9 propagates along the axis of the illuminated channel 4 of the straight-line fiber 3 (see Fig. 1) from the emitter 8 to the photodetector 11. The signal from the output of the photodetector 11 through the amplifier 12 is fed to the input of the processing unit 13 and prevents the formation of its alarm output.

When the controlled surface 6 is deformed, the light guide 3 rigidly connected with it bends (see Fig. 2). As a result, beam 9 propagating rectilinearly in the glass (see FIG. 3) hits the interface 5 of the radiation-tinted and transparent regions of the curved glass fiber at an angle of 14 ά and is refracted at the incidence point at an angle of 15 β. Since the refractive index of radiation-tinted glass 3 (nton = 1.52) exceeds the refractive index of transparent glass 4 (npr = 1.50), the angle ά> β [12, p.305]. Therefore, the beam 10 deviates at the point of refraction in the direction of removal from the optically transparent channel 4 (that is, deviates into the thickness of the radiation-tinted glass 3) regardless of the actual value of the angle ά (from 0 to 90 °). This means that at no interface 5 the effect of total internal reflection of the incident beam 9 can manifest itself (this effect could lead, in case of its manifestation, to the propagation of signal radiation 10 inside the optically transparent channel 4 with almost no attenuation loss [ 12, p.306]),

When the beam 10 propagates in the radiation-tinted (dark) part of the optical fiber 3, the intensity of the electromagnetic optical radiation decreases, since this region of the optical fiber is characterized by a higher optical density [12, p.305, 352].

For these reasons, when the fiber 3 is bent, the damped radiation 10 does not reach the photodetector 11, which leads to the disappearance of the inhibitory signal at the output of the amplifier 12 and, as a result, the processing unit 13 generates an alarm.

To increase the sensitivity of the signal device to small deformations of the surface being monitored (that is, to deformations that result in slight bending of the optical fiber 3), it is necessary to increase the length of the optically transparent channel 4, since the amount of shift of the light spot of the signal radiation 9 along the surface of the photodetector 11 is proportional to the length of the channel.

However, such a design solution leads to an increase in the longitudinal dimension of the optical fiber 3, which makes it difficult to use it on small controlled surfaces 6 with their slight deformation. In this regard, it is proposed to carry out laser processing of the radiation-tinted optical fiber 3 according to the scheme shown in figure 4. The result of such processing of the fiber is the formation of a multiply broken optically transparent channel 4 and, as a result, a significant increase in its length due to the repeated re-reflection of the laser beam of the processing radiation 2 from the side mirror surfaces 16 of the fiber 3. In this case, the overall overall length of the fiber 3 remains unchanged.

It should be noted here that the processing of the glass fiber 3 according to the scheme shown in Fig. 4 provides the possibility of manufacturing signaling devices recording longitudinal strains. This is explained by the fact that with longitudinal deformation the length of the fiber increases, but the optical spatial distribution of the signal radiation 9 in the multiply broken channel 4 remains unchanged. As a result, the light spot of the signal radiation 9 is shifted along the surface of the photodetector 11 up to its sensitivity limit.

To control the surface 6 of a complex shape (see figure 5) (for example, cylindrical, spherical, wavy, etc.) it is necessary: to make a glass fiber 3 that repeats the shape of the controlled surface 6; apply a layer of reflective mirror metallization 16 to its lateral surfaces; radiation-tint the glass of optical fiber 3 and then fix the optical fiber 3 firmly on the shape-appropriate portion of the surface under control 6. Laser processing of the optical fiber 3 (formation of an optically transparent channel 4) should be carried out at the place of installation of the signal device on the surface of the controlled object 6.

With significant elastic or residual plastic deformation of the controlled surface 6 (both transverse and longitudinal) as a result of accidental or intentional external impact or static impact, the glass fiber 3 is destroyed (cracked), which causes the scattering of signal radiation 9 on the chips and in the glass cracks and, as a result, the immediate activation of the alarm device.

In the serial production of glass fibers of various standard or unified shapes and sizes (large batches of which are subjected to simultaneous group metallization and then radiation tinting), the cost of manufacturing and operating signaling devices ready for use is significantly reduced. This provides the possibility of widespread use of the proposed method for solving the control and protective protection of various objects subjected to deforming effects of both external and internal forces, as well as the possibility of quick replacement of optical fibers in some cases of damage when the alarm is triggered or during a planned reconfiguration of parameters or modernization alarm elements on controlled surfaces.

The proposed method of manufacturing alarm burglar alarm devices allows you to combine part of the manufacturing operations of the optical system with its installation on the surface of the controlled object and thereby increase the reliability of the alarm system as a whole due to the possibility of tuning the optical system at the installation site. In addition, this provides a significant increase in the sensitivity of the security alarm to mechanical influences.

Considering that glass as a structural material provides a wide variety of shapes and sizes of practical implementation of flexible optical fibers, the proposed method allows for the effective solution of the problem of controlling the magnitude of deformation and the degree of destruction of load-bearing elements of various sizes and sizes. In this case, glass tinted optical fibers as destruction sensors can be installed in advance at any places of possible deformation of individual structural elements with a delay in mounting the signal device as a whole until the scheduled inspection is carried out in a timely manner,

Information sources

1. US patent No. 3970846, CL. 250-221, publ. 1976 (analog).

2. A.S. No. 970411, IPC G08B 13/18. Optical sensor of fire alarm / Kulakov A.T. - Stated 04/03/1981. - Publ. 10/30/1982, bull. No. 40 (analogue).

3. A.S. No. 195689, IPC G01B 11/18. The method of measuring strain / Sheinin I.S., Noskov L.D. - Stated 04/18/1966. - Publ. 05/04/1967, bull. No. 10 (prototype).

4. REA Designer Handbook: Components, Mechanisms, Reliability / N.A. Barkanov, B.E. Berdichevsky, P.D. Verkhopyatnitsky, etc. Ed. R.G. Varlamova. - M .: Radio and communications, 1985 .-- 384 p., Ill.

5. Machulka G.A. Laser processing of glass. - M .: Owls. Radio, 1979. - 136 p., ill.

6. Stepanenko I.P. Fundamentals of Microelectronics: Textbook for universities. - M .: Owls. Radio, 1980 .-- 424 p., ill.

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Claims (1)

A method of manufacturing signal devices that are triggered due to interruption of the light flux of signal radiation during deformation of the surface of the controlled object and containing an emitter optically coupled through a flexible glass fiber with a photodetector, including their manufacture and installation on the surface of the controlled object, characterized in that after the flexible a glass fiber with polished side surfaces, a thin reflective layer is applied to them and a glass fiber is exposed for the sake of tinting with electromagnetic x-ray or gamma radiation up to a dose of 10 kGy, then the fiber is rigidly fixed on the surface of the object being monitored and a beam of sharply focused pulsed or continuous laser radiation with a focal length many times the length of the fiber with a laser wavelength corresponding to the transparency range is passed through it glass and an energy of up to 50 mJ for a period of time up to 60 s, sufficient to form a narrow channel in the glass fiber throughout the length of the fiber, and when the channel is formed, the transparency of the glass is restored along the propagation axis of the laser processing radiation, then a source of narrowly directed pulsed or continuous radiation of low intensity is connected to the fiber input at an angle to the longitudinal axis of the fiber with a wavelength corresponding to the wavelength of the laser processing radiation.

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