RU2369996C1 - Laser positioner for x-ray emitter - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention can be used for aligning an X-ray emitter with respect to an object. The laser positioner for an X-ray emitter has a housing in which there is a laser, a first mirror made from organic glass, mounted at the intersection of the optical axes of the laser and X-ray beams, which directs onto the object a laser beam, concentric with the X-ray beam, a television system, consisting of a CCD matrix, a lens and a monitor, a linear scale, digitised in distances from the object to the X-ray emitter, which is projected on the CCD matrix using the first semi-transparent mirror and the lens and which is viewed on the screen of the monitor simultaneously with the image of the controlled zone of the object and ring structures formed by the laser beam. The positioner also contains a rotor with an central opening, lying on the axis of the laser between the laser and the first mirror with possibility of rotation, on the surface of the rotor, facing the perpendicular axis of the laser and the first mirror, along one of its radii there is a second mirror, mounted at an angle of 45° to the axis of the laser at a distance R from the laser and in series with a second semi-transparent mirror, mounted at an angle

to the axis of the laser at a distance H from the laser, where α - is the angle of divergence of the X-ray beam and a third semitransparent mirror, mounted in front of the central opening of the rotor directly on the axis of the laser at an angle of 45°, the plane of the second mirror and third semi-transparent mirror are parallel to each other.

EFFECT: increased intensity of laser radiation, provision for illumination of the centre of the zone illuminated by the laser, simpler design.

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Description

The invention relates to the field of non-destructive testing of objects using x-ray radiation.

A device is known that includes a laser, two mirrors, the first mirror is mounted at the intersection of the optical axes of the laser and x-ray beams and directs laser beams concentric to the x-ray beams, a linear scale, a telescope for expanding and collimating laser radiation, which allows to form and lens actual image of a luminous disc, television system. A feature of the device is an annular matrix of lasers located in the rear focal plane of the lens, and the diameter of the circle of arrangement of the lasers of the matrix is given by a certain ratio. The technical result of the invention is the ability to evaluate the size of the studied area of the object [1].

The disadvantage of this invention is the low efficiency of the use of laser radiation due to the expansion of the laser beam, which leads to a sharp decrease in its brightness; the laser matrix is difficult to align when tuning the angles of laser radiation relative to the axis of the x-ray beam when changing the angle of divergence; the telescope lens with the actual size of the laser spot on the object has a large diameter (100 mm or more), which dramatically increases its cost and manufacturing complexity. In addition, there is no illumination of the center of the laser-illuminated zone, which complicates the orientation of the centralizer relative to the object.

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

к оси лазера на расстоянии Н от нее, и третье полупрозрачное зеркало, установленное перед центральным отверстием ротора непосредственно на оси лазера под углом 45° к ней, плоскости второго зеркала и третьего полупрозрачного зеркала параллельны друг другу, а расстояние от поверхности ротора до первого зеркала по оси лазера выбирается из соотношения

, где А - расстояние от анода рентгеновской трубки до центра первого зеркала, где α - угол расходимости рентгеновского пучка.To do this, into a centralizer for an x-ray emitter, comprising a housing in which a laser is located, the optical axis of which is parallel to the longitudinal axis of the x-ray emitter, a first plexiglass mirror mounted at the intersection of the optical axes of the laser and x-ray beams perpendicular to the plane formed by them and directing the laser beam to the object, concentric to an x-ray beam, a television system consisting of a CCD matrix, a lens and a monitor, a linear scale digitized at distances from the object to the x-ray of the new radiator, which is projected onto the CCD using the first translucent mirror and lens, and which is observed on the monitor screen simultaneously with the image of the controlled area of the object and the ring structures formed by the laser beam, an additional rotor with a central axial hole is placed on the laser axis between it and the first mirror with the possibility of rotation using an electric or other drive relative to the axis of the laser with a frequency f≥10 Hz, on the surface of the rotor facing the perpendicular the second axis of the laser and to the first mirror, along one of its radii, sequentially placed at an angle of 45 ° to the laser axis at a distance R from it, the second translucent mirror mounted at an angle

to the laser axis at a distance H from it, and a third translucent mirror mounted in front of the central rotor hole directly on the laser axis at an angle of 45 ° to it, the planes of the second mirror and the third translucent mirror are parallel to each other, and the distance from the rotor surface to the first mirror is laser axis is selected from the ratio

where A is the distance from the anode of the x-ray tube to the center of the first mirror, where α is the angle of divergence of the x-ray beam.

The device diagram is shown in figure 1.

The laser centralizer includes a housing 2, which is mounted on the x-ray emitter 1. In the housing 2 there is a laser 8, the axis of which is parallel to the longitudinal axis of the emitter is the first plexiglass mirror 3, mounted at the intersection of the laser axes and the x-ray beam.

On the axis of the laser 8, at a distance t = A + B from the center of the first mirror, there is a rotor 4 with a central hole with a diameter d≥d _l , rotated relative to the laser axis, where d _l is the diameter of the laser beam, using an electric motor 10 and a friction clutch or gear 9 .

к оси лазера на расстоянии Н от нее, и третье полупрозрачное зеркало 7, установленное перед центральным отверстием ротора 4 непосредственно на оси лазера под углом 45° к ней. Плоскости второго зеркала, а также второго и третьего полупрозрачных зеркал перпендикулярны плоскости, образуемой радиусом ротора, вдоль которого установлены эти оптические элементы.On the surface of the rotor 4, perpendicular to the laser axis, along one of its radii are located a second mirror 5, mounted at an angle of 45 ° to the laser axis at a distance R from it, a second translucent mirror 6, installed at an angle

to the laser axis at a distance H from it, and a third translucent mirror 7 mounted in front of the Central hole of the rotor 4 directly on the laser axis at an angle of 45 ° to it. The planes of the second mirror, as well as the second and third translucent mirrors, are perpendicular to the plane formed by the radius of the rotor along which these optical elements are mounted.

A television system 11, consisting of a lens 13 and a CCD matrix 12, is also installed on housing 2. Video images are observed on the monitor screen 14. A linear scale 16, digitized in units of distance from the object to the x-ray emitter, is installed in the focal plane of the collimator 15 and is illuminated by a light source 17 and is projected by a lens 13 with a focal length f ₀ using the first translucent mirror 14 '. The angle of view of the television system is selected taking into account w≥α.

In front of the lens 13, a narrow-plane filter 18 can be installed to increase the contrast of the image under conditions of solar illumination, the passband of which corresponds to the wavelength of the laser 8.

Figure 1, b shows a view of the monitor screen.

The device operates as follows. The rays of the laser 8 partially pass through the hole of the rotor 4, the translucent mirror 7, after reflection from the first mirror 3, propagates on the axis of the x-ray beam, forming a bright dot on the object in the center of its transmission zone.

The rays reflected from the translucent mirror 7 are directed along the radius of the rotor 4 and, after reflection by the second translucent mirror 6, are directed at an angle α / 2 to the laser axis to the first mirror 3 and, after reflection from it, are directed at the object at an angle α / 2.

The radiation of the laser 8, passing the second translucent mirror 6, is sent to the second mirror 5, reflected from it and the first mirror 3 and sent to the object 18 parallel to the axis of the x-ray beam at a distance R from it. It is essential that the central laser beam and the rays reflected from the second translucent mirror 6 and the second mirror 5 lie in the same plane. Therefore, when the rotor 4 rotates, they create in space the surface of the cone and cylinder located on the same axis that coincides with the axis of the x-ray beam.

In this case, images of two rings and a central bright point corresponding to the intersection of the axis of the x-ray beam with the object appear on the object.

The diameter of the ring formed by the cylindrical beam of rays is obviously equal to D '= 2R and remains constant when the distance from the object to the x-ray emitter changes, this allows you to use it as a basic element in determining the distance from the object to the x-ray emitter using the known relationships of geometric optics, linking the image size of this ring with an increase in the optical system, depending on the distance to the object L [2].

, что позволяет использовать его для оценки зоны объекта, просвечиваемой рентгеновским излучением.The diameter on the object of the ring formed by the conical beam formed during the rotation of the second translucent mirror 5 on the rotor 4 is related to the distance to the object by the obvious relation

, which allows you to use it to assess the area of the object, transmitted through x-ray radiation.

This is ensured by the coincidence of the apex of the conical beam of rays formed by the rotation of the second translucent mirror 6 on the rotor 4 with a point on the laser axis at a distance A equal to the distance from the anode to the x-ray tube to the center a of the first mirror 3.

выбран с учетом геометрических соотношений, показанных на фиг.2.The angle of inclination of the second translucent mirror 6 to the axis of the laser beam

selected taking into account the geometric relationships shown in figure 2.

. Таким образом, расстояние от второго полупрозрачного зеркала до лазера определяется углом расхождения рентгеновского пучка и конструктивным параметром В, что позволяет легко перестраивать геометрию пучка конических лучей при вращении ротора 4.From a right triangle OMK we have

. Thus, the distance from the second translucent mirror to the laser is determined by the angle of divergence of the x-ray beam and structural parameter B, which makes it easy to reconstruct the geometry of the beam of conical rays during rotation of the rotor 4.

.It is clear that in this case, the angle of inclination φ of the second translucent mirror has a single value equal to

.

откуда

.Indeed, from a right triangle OMK we have

where from

.

.Considering the angles adjacent to the OD axis, we obtain 2γ = 180 ° -β, whence

.

.In view of (2), we obtain

.

.From the rectangle OCD we have finally

.

по определению) и перпендикулярна СО, направление которого совпадает с радиусом ротора 4. По известному закону отражения геометрической оптики нормаль MN к поверхности второго полупрозрачного зеркала 6, угла КМО (угол падения равен углу отражения).Note that the hypotenuse of the triangle OCD, which coincides with the surface of the translucent mirror 6, is drawn through the point O of intersection of the line PO (side of the OPC angle equal to

by definition) and is perpendicular to the CO, the direction of which coincides with the radius of the rotor 4. According to the well-known law of reflection of geometric optics, the normal MN to the surface of the second translucent mirror 6, the KMO angle (the angle of incidence is equal to the angle of reflection).

In the process of alignment and orientation of the x-ray emitter, the operator turns on the rotor 4 drive and observes the picture shown in Fig. 1, b on the monitor screen. Combine the center of the annular zones with the desired site of the object and determine the distance from the object to the x-ray emitter, evaluating it by the number of scale divisions per image of the base (inner) ring, acting similarly to the procedure described in the patent analogue [1].

At the same time, the size of the object’s translucent zone is estimated by the diameter of the outer ring and, if necessary, the distance from the object to the emitter is changed, achieving the desired translucent zone.

The use of a scanning laser system instead of a telescopic laser beam expander made it possible to sharply (up to 100 times) increase the brightness of laser structures at the object, and also significantly simplify the process of reconstructing the angle of divergence of laser beams when changing the angle of divergence of an x-ray beam when replacing an x-ray tube, etc.

The process of changing the diameter of the base hollow cylindrical beam of rays was also simplified, which can be used to adjust the range of distances of the radiation object and / or the measurement error of these values.

It is significant that in the proposed device there is one laser that performs three functions - highlighting the center of the controlled area of the object, forming a luminous ring on its surface, the displaced diameter of which coincides with the boundaries of the zone of the object, illuminated by the x-ray beam of a particular emitter, and, finally, forming an image on the surface of the object luminous ring of constant diameter, independent of the distance between the object and the x-ray emitter, which is used to realize the long-range fun tion centralizer.

At the same time, nine lasers were used in the analogue !!! This dramatically increases the cost and complexity of aligning the optical system of the centralizer.

The rotor rotational speed is selected in the frequency range f≥10 Hz to ensure the fused perception of dynamic laser structures (rings) formed by moving laser beams.

As a television system, the centralizer uses a standard video camera, while there is no need to use large-diameter lenses (as in the patent analogue). The optical elements of the television system are now not connected to the telescope, which ensured a free constructive layout when placing the video camera in the centralizer case.

To design the measuring scale on the CCD matrix of the television system, a common scheme based on a collimator with a translucent mirror mounted at the input of the camera’s lens was used.

It also significantly strengthened the design and made it more flexible, with the ability to quickly replace (if necessary, for example, change the measurement range, image scale, etc.) of both the scale and the collimator as a whole. It is important that the illumination of the scale is produced from a stable external light source (for example, an LED) in the collimator, and not from scattered laser light, as in the analogue, which led to a dependence of the brightness of the scale on the intensity of the light reflected from the object.

Literature

1. RF patent N2237984.

2. Turygin I.A. Applied Optics, Vol. 1 and 2. M .: Mechanical Engineering, 1986, 350 p.

Claims (1)

A laser centralizer for an x-ray emitter, comprising a housing in which a laser is located, the optical axis of which is parallel to the longitudinal axis of the x-ray emitter, a first plexiglass mirror mounted at the intersection of the optical axes of the laser and the x-ray beams perpendicular to the plane they form and directing the laser beam concentric to the x-ray beam, a television system consisting of a CCD matrix, a lens and a monitor, a linear scale digitized at distances from the object to x-rays emitter, which is projected onto the CCD using the first translucent mirror and lens, and which is observed on the monitor screen simultaneously with the image of the controlled area of the object and the ring structures formed by the laser beam, characterized in that the rotor with a central axial hole is additionally introduced into the centralizer, placed on the laser axis between it and the first mirror with the possibility of rotation using an electric or other drive relative to the laser axis with a frequency f≥10 Hz, on the surface of the roto the second mirror, mounted at an angle of 45 ° to the laser axis at a distance R from it, the second translucent mirror mounted at an angle

to the laser axis at a distance H from it, and a third translucent mirror mounted in front of the central rotor hole directly on the laser axis at an angle of 45 ° to it, the planes of the second mirror and the third translucent mirror are parallel to each other, and the distance from the rotor surface to the first mirror is laser axis is selected from the ratio

,
where A is the distance from the anode of the x-ray tube to the center of the first mirror;
α is the angle of divergence of the x-ray beam.

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