RU2404551C1 - Laser centraliser for x-ray emitter - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: laser centraliser of X-rays also includes a device for digital conversion of turns of the second reflector into linear displacements, made in form of a lever which is rigidly attached to the second reflector, where displacement of said lever is recorded using a digital indicator whose measuring probe is in contact with the lever at a point lying at a distance R from its axis of rotation, defined by the relationship R=2x/w, where w=1/2(U1-U2), U1 and U2 are parallax angles of the point of intersection of the object with the axis of the X-ray beam for distances S1 and S2 from the object to the X-ray emitter, respectively, U1=arctg(S1/B), U2=arctg(S2/B), B is distance from the centre of the first reflector to the axis of rotation of the second reflector, x is linear displacement of the probe of the indicator, corresponding to turning of the lever by an angle w, x=(S1-S2)/k, k=1000 is the coefficient of decimal reduction of the scale of the indicator.

EFFECT: reduced error in apparatus for indicating distance from an object to an X-ray emitter in low illumination conditions.

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Description

The invention relates to non-destructive testing using x-ray radiation and can be used to control materials and products in various industries.

Known laser centralizer for an x-ray emitter, containing a laser with two-sided output of radiation and two reflectors, the first reflector is installed at the intersection of the optical axes of the laser and x-ray beams, the second is on the optical axis of the exit of laser radiation from its second end, a means of indicating the distance from the x-ray emitter to the object , two cylindrical lenses mounted on the axis of the laser in front of its ends, the first of which can be removed from the laser beam and replaced with a spherical lens that forms a conical light beam that is adequate in structure to the x-ray beam and creates a disk image on the surface of the object, the degree of elliptical distortion of which determines the perpendicularity of the surface of the object to the axis of the x-ray beam with the possibility of quantification using scales on the monitor screen of the television system, which is part of the centralizer [one].

The disadvantages of this device are the lack of a digital reading device in the means of indicating the distance from the object to the x-ray emitter, which leads to a significant subjective error of the rangefinder unit of the centralizer, as well as the absence of means for spectral selection of images of laser strips on the object and its general illumination, which is extremely important when radiography in low light conditions, such as in the evening.

The purpose of the invention is the elimination of these disadvantages.

To do this, in a laser centralizer containing a housing in which there is a laser with a two-sided output of radiation, two reflectors, the first of which is mounted at the intersection of the axes of the laser and the x-ray beam, and the second is mounted on the axis of the laser in front of its second end with the possibility of rotation about an axis passing through its center perpendicular to the plane formed by the axes of the laser and the x-ray beam, two cylindrical lenses, the first of which is located on the laser axis between it and the first reflector with the possibility of input-output from an azero beam, and the second is mounted on the laser axis in front of the second reflector, a spherical lens that is installed instead of the first cylindrical lens and forms a conical laser beam coaxial with the x-ray beam, having the same angle of divergence and used to estimate the size of the area of the object exposed to x-ray radiation , as well as the perpendicularity of its surface to the axis of the x-ray beam according to the degree of ellipticity of the light disk formed by this beam on the object, a beam splitter installed on the laser axis between the first reflector and the first cylindrical lens at an angle of 45 degrees to this axis perpendicular to the plane formed by the axes of the laser and the x-ray beam, a television camera, the optical axis, the lens of which coincides with the axis drawn from the center of the beam splitter perpendicular to the laser axis and on the monitor screen which measuring scales can be set to quantify the size of defects in the surface of an object and its perpendicularity to the x-ray beam, an additional digital conversion is introduced The indicator of rotations of the second reflector into linear displacements, made in the form of a lever rigidly fastened to the second reflector, the movements of which are recorded using a digital indicator, the measuring probe of which contacts the lever at a point located at a distance r from its axis of rotation, determined from the relation R = 2X / W, where W = 1/2 (U1-U2), U1 and U2 are the parallactic angles of the point of intersection of the object with the x-ray axis for the distances S1 and S2 from the object to the x-ray emitter, respectively, U1 = arctg (S1 / B), U2 = arctan (S2 / B), B - distance from the center of the first reflector to the axis of rotation of the second reflector, X is the linear displacement of the indicator probe corresponding to the rotation of the lever by an angle W, X = (S1-S2) / k, k = 1000 is the decimal reduction coefficient of the indicator scale, at which its readings in millimeters numerically correspond to the distance from the object to the x-ray emitter in meters, an interference filter is installed in front of the lens with the possibility of input-output, the passband of which coincides with the laser wavelength, light sources are placed on the body, the angle of radiation whose values are equal to or greater than the angle of the field of view of the camera lens, the optical axes are parallel to the axis of the x-ray beam, and the radiation power and spectrum are selected taking into account the specifics of using the centralizer in specific conditions.

The invention is illustrated by drawings, on which a centralizer diagram is presented.

The laser centralizer contains an x-ray emitter 1, to which a housing 2 is attached, in which the first plexiglass reflector 3, a beam splitter 4, a cylindrical 5 and a spherical 11 lens, a laser 6 with a two-sided radiation output, a second cylindrical lens 7, a second reflector 8, a lever 9 are located , a digital indicator 10, a camera 12 with a monitor 13, an interference filter 14, a source 15 of the illumination of the object 16.

Figure 2 explains the operation of a digital indicator of the distances from the object to the x-ray emitter.

As can be seen from figure 2, when moving the object from the x-ray emitter from the minimum to the maximum position (distances S1 and S2, respectively), the corresponding parallactic corners U1 and U2 change by the amount W = U1-U2. Moreover, as is known [2], to deflect the laser beam by this angle, it is sufficient to rotate the second reflector by the angle W / 2. The linear displacement of the laser beam on the surface of an object located at a distance S1 from the X-ray emitter can be estimated by the approximate equality D = S × W, taking into account the smallness of the angle (W = 3 angular degrees, for real designs of centralizers with characteristic values of the parameters B = 0.3 m, S = 4-6 m). To use a standard digital indicator with a linear metric scale, graduated in millimeters, it is obviously necessary that the value of D in meters corresponds to the value of X in mm, numerically equal to it. For this, it is necessary that X = D / k = D / 1000. The required value of R is determined in this case from the expression R = X / W, as follows from the analysis of such triangles AOB and SOE.

The centralizer works as follows.

When the lenses 5 and 11 are removed from the laser beam, the laser 5 forms a bright dot on the object 16, which, using the means of moving the centralizer, is combined with the center of the controlled zone. Then, the lens 11 is introduced into the laser beam, and the image of the light disk is observed on the monitor. If it has ellipticity, it is eliminated by performing linear and angular movements of the centralizer. If necessary, a quantitative assessment of the degree of ellipticity of the disk and / or the size of the defects on the surface of the object using measuring scales on the monitor screen is performed. After that, the lens 11 is withdrawn and the first cylindrical lens is introduced. Observe the images of the moving and stationary laser strips on the monitor and, rotating the second reflector with its drive (for example, with a microscrew in contact with the lever 9), achieve the alignment of the strips and take readings from the display of the digital indicator, equal to the distance from the object to the x-ray emitter, expressed in meters. Then proceed directly to the radiation control procedures.

Information sources

1. RF patent 2250575. Laser centralizer.

2. Reference designer of optical-mechanical devices, Panov V.A. et al., L., Mechanical Engineering, 1980, 742 pp.

Claims (1)

A laser centralizer comprising a housing in which there is a laser with a two-sided output of radiation, two reflectors, the first of which is mounted at the intersection of the axes of the laser and the x-ray beam, and the second is mounted on the axis of the laser in front of its second end with the possibility of rotation about an axis passing through its center perpendicular to the plane formed by the axes of the laser and the x-ray beam, two cylindrical lenses, the first of which is located on the laser axis between it and the first reflector with the possibility of input-output from the laser beam ka, and the second is mounted on the laser axis in front of the second reflector, a spherical lens that is installed instead of the first cylindrical lens and forms a conical laser beam coaxial with the x-ray beam, having the same angle of divergence and used to estimate the size of the area of the object that is exposed to x-ray radiation, as well as the perpendicularity of its surface to the axis of the x-ray beam according to the degree of ellipticity of the light disk formed by this beam on the object, a beam splitter mounted on the laser axis between the first reflector and the first cylindrical lens at an angle of 45 ° to this axis perpendicular to the plane formed by the axes of the laser and the x-ray beam, a camera whose optical axis of the lens coincides with the axis drawn from the center of the beam splitter perpendicular to the laser axis, and on the monitor screen of which measurement scales for quantifying the size of defects in the surface of an object and its perpendicularity to the x-ray beam, an additional digital converter of turns in of the reflector in linear displacements, made in the form of a lever rigidly fastened to the second reflector, the movements of which are recorded using a digital indicator, the measuring probe of which contacts the lever at a point located at a distance r from its axis of rotation, determined from the relation R = 2X / W , where W = 1/2 (U1-U2), U1 and U2 are the parallactic angles of the point of intersection of the object with the axis of the x-ray beam for the distances S1 and S2 from the object to the x-ray emitter, respectively, U1 = arctan (S1 / B), U2 = arctg (S2 / B), B - distance from the center of the first of the reflector to the axis of rotation of the second reflector, X is the linear displacement of the indicator probe corresponding to the rotation of the lever through the angle W, X = (S1-S2) / k, k = 1000 is the decimal reduction coefficient of the indicator scale at which its readings in millimeters numerically correspond to the distances from the object to the x-ray emitter in meters, an interference filter is installed with the possibility of input-output in front of the lens, the passband of which coincides with the laser wavelength, light sources are placed on the body, the radiation angle of which is equal to or exceed the visual field angle lens camera, the optical axes are parallel to the axis of the X-ray beam, and the power and emission spectrum are selected based on the specific application of the centralizer in specific conditions.

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