RU2315448C1 - Laser localizer for x-ray emitter - Google Patents

Abstract

FIELD: x-ray technologies, possible use for orientation of x-ray emitter relatively to object.

SUBSTANCE: in accordance to the invention, second and digital photo-camera is additionally introduced, analogical to first one, objective axis of which is parallel to objective axis of first digital photo-camera and axis of x-ray beam, axes of objectives of both digital photo-cameras are positioned at distance B from each other and lie in a plane, formed by axes of laser and x-ray beam, objective axis of first digital photo-camera is positioned at distance 1≥t+A/2 from the axis of x-ray beam, where t=Δ·tg(α/2), Δ - distance from focus of x-ray emitter to charge-coupled matrix of first digital photo-camera with AxA size, α - emission angle of x-ray emitter, both digital photo-cameras are positioned at one distance Δ, sight angles of both digital photo-cameras, having objectives with identical focal distance f' and identical charge-coupled matrices with AxA size, satisfy condition

and computed distance D from object to x-ray emitter is determined from formula D=Δ+D₀, where

where P=X₂-X₁ - parallax of images of laser spot on an object, coinciding with its point of intersection with x-ray beam axis, X₁ and X₂ - distances from points of intersection of axes of objectives of first and, respectively, second digital photo-cameras with corresponding charge-coupled matrices to image of laser spot on charge-coupled matrix of first and, respectively, second digital photo-camera.

EFFECT: increased precision of aiming of x-ray emitter at selected control object zone.

1 dwg

Description

The invention relates to non-destructive testing of materials and products using x-ray radiation and can be used to control objects of aerospace engineering and other industries.

Known laser centralizer, which includes lasers, a television system, a reflector mounted at the intersection of the axis of the lens of the television system and the x-ray beam, while the axis of the lasers are parallel to each other and the axis of the x-ray beam and form on the object two spots located at a certain distance from each other friend.

The distance between the images of the spots of the CCD plane — the matrix of the television system — judges the distance from the object to the x-ray emitter [1].

The disadvantages of this device:

the absence of a laser mark corresponding to the point of intersection of the axis of the x-ray beam with the object, which interferes with the precise guidance of the x-ray emitter to the desired area of the control object;

as a rule, objects of aerospace engineering have a complex structure, various protrusions, cavities, etc. elements, as a result of which one of the spots can be screened by these elements and / or located at a level different from the other spot, which reduces the accuracy of measurements, and in some cases makes them impossible;

Improving the measurement accuracy in this device is possible only by increasing the base of the rangemeter, i.e. increasing the distance between the axes of the lasers. However, due to the above features of the design of objects of aerospace technology, other objects of special equipment, this is almost impossible.

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

To do this, into a laser centralizer for an x-ray emitter, comprising a housing with a laser located in it, whose axis is parallel to the longitudinal axis of the x-ray emitter, a plexiglass reflector mounted at the intersection of the laser and x-ray beam axes, a digital camera and a television computer or computer to determine the distance from the object to the X-ray emitter and monitor, a second digital camera is additionally introduced similar to the first, the axis of the lens of which is parallel to the axis of the lens of the first digit of the new camera and the axis of the x-ray beam, the axis of the lenses of both digital cameras are located at a distance B from each other and lie in a plane formed by the axes of the laser and the x-ray beam, the axis of the lens of the first digital camera is located at a distance l≥t + A / 2 from the axis of the x-ray beam where t = Δtg (α / 2),

, а вычисленное расстояние D от объекта до рентгеновского излучателя определяется по формулеΔ is the distance from the focus of the x-ray emitter to the CCD matrix of the first digital camera of size A × A, α is the angle of radiation of the x-ray emitter, both digital cameras are located at the same distance Δ, the angles of the field of view β of both digital cameras having lenses with the same focal length f 'and identical CCD matrices of size A × A satisfy the condition

, and the calculated distance D from the object to the x-ray emitter is determined by the formula

D = Δ + D _o , where

, где Р=Х₂-Х₁ - параллакс изображений лазерного пятна на объекте, совпадающего с точкой его пересечения осью рентгеновского пучка,

where P = X ₂ -X ₁ - the parallax image of the laser spot on the object, coinciding with the point of intersection with the axis of the x-ray beam,

X ₁ and X ₂ are the distances from the intersection points of the axes of the lenses of the first and, accordingly, the second digital cameras with corresponding CCD arrays to the image of the laser spot on the CCD matrix of the first and, respectively, second digital cameras.

The device diagram is shown in the drawing.

The laser centralizer contains a housing 2 mounted on the x-ray emitter 1, in which the laser 4 is located, the axis of which is parallel to the longitudinal axis of the x-ray emitter, plexiglass reflector 3 mounted at the intersection of the laser and x-ray axes so that after reflections from it the laser beam coincides in direction with the axis of the x-ray beam, two identical digital cameras containing CCDs 5 and 5 'of size A × A and lenses 6 and 6' with the same focal length f '. The video signal of the first digital camera is sent to the monitor 7 and the first input of the television transmitter or computer 8. The video signal from the second digital camera is sent directly to the second input of the television transmitter or computer 8.

The CCDs of both digital cameras are removed from the longitudinal axis of the x-ray emitter by the same distance Δ, and their planes are perpendicular to the axes of the lenses 6 and 6, parallel to each other in the plane formed by the axes of the x-ray and laser beams.

, необходимому для того, чтобы при изменениях расстояния от объекта до рентгеновского излучателя изображение лазерного пятна не уходило за пределы ПЗС-матрицы цифровых фотокамер, особенно при минимальных значениях этого расстояния.The laser 4 forms a bright spot on the object 9, which coincides with the point of intersection of the object with the axis of the x-ray beam. In this case, images of the laser spot are formed on the CCD matrices 5 and 5 'with lenses 6 and 6', respectively. The distances from the points of intersection of the axes of the lenses 6 and 6 'with the matrices 5 and 5' will be equal, with X ₂ > X ₁ , respectively, due to different viewing angles of the laser spot with lenses 6 and 6 '. Fields of view of digital cameras meet the condition

necessary to ensure that when the distance from the object to the x-ray emitter changes, the image of the laser spot does not go beyond the CCD matrix of digital cameras, especially at minimum values of this distance.

, где t=Δ·tg (α/2).The first digital camera, which is closer than the second, to the axis of the x-ray beam, must be outside the propagation zone of the x-ray beam, i.e. the condition must be met

, where t = Δtg (α / 2).

In this case, the second digital camera, located at a distance of (B + l)> l from the axis of the x-ray beam, is obviously also located outside the x-ray beam propagation zone.

The measurement of the distance from the object to the x-ray emitter is determined by the formula D = D ₀ + Δ (see drawing). The value of D ₀ is associated with the parameters of the optical system of the centralizer by relations, the conclusion of which is given below.

From similar triangles O ₁ AM and O ₁ EF, as well as AC О ₂ and О ₂ NH, we have

.where do we get

.

From the last equality it follows

after appropriate transformations

l · X ₂ = X ₁ (B + l) = X ₁ B + X ₁ · l, whence we have

l · X ₂ -l · X ₁ = B · X ₁ and l · P = B · X ₁ ,

, то после подстановки в уравнение (1) окончательно получим

и

.where P = X ₂ -X ₁ is the parallax of the images of the laser spot on the matrices 5 and 5 ', corresponding to the current distance D ₀ from the object to the x-ray emitter. Because

, then after substituting into equation (1) we finally obtain

and

.

Let us evaluate the error of measuring the distance from the object to the x-ray emitter for the characteristic values of the values, in the practically used control modes and adopted in the pilot version of the centralizer.

We take f '= 50 mm, B = 500 mm, l = 100 mm, Δ = 500 mm, D ₀ = 5 m. Moreover, P = X ₂ -X ₁ defined by formula (3) will be equal to P = 5 mm = 5000 μm; because the pixel size of the CCD is P = 10 μm, then the relative error of the parallax measurement will be

.

.

, откуда ΔD₀=D₀·0,002=5000·0,002=10 мм, что вполне отвечает требованиям практики.Accordingly, the measurement error

, whence ΔD ₀ = D ₀ · 0.002 = 5000 · 0.002 = 10 mm, which fully meets the requirements of practice.

This estimate is given practically for D ₀ = D _{0 max} , i.e. for the maximum object. For D ₀ <D _max , the measurement error will obviously be even smaller. The size of the CCD matrix in the centralizer layout is A = 25 mm or I ^th , which allows measurements at D _{0 min} ≥2.0 m, which is also sufficient for real control situations.

Note that to increase the measurement accuracy, you can increase the base β and the focal length of the lenses f ', which is easy to implement.

The coordinates of the images of the laser spot on the object X ₁ and X ₂ and on the matrices 5 and 5 'are easily calculated, because due to the high accuracy of manufacturing rasters of CCD matrices and optical-mechanical components of digital cameras, the position of the point of intersection of the axes of the lenses with CCD matrices corresponds to the center of symmetry of these matrices, i.e. value A / 2.

It is also possible to count the coordinates of the image of the spots from the edge of the CCD matrix. In this case, it is obvious that parallax will not change its value.

,

,Indeed let

,

,

where X ₀ = A / 2 is the coordinate of the center of the CCD matrix, and the coordinates of the spot images, measured from the edge of the CCD matrix.

, т.е. величина параллакса осталась неизмененной.It's obvious that

, i.e. the parallax value remained unchanged.

The centralizer works as follows.

The operator turns off the laser, the monitor and digital cameras, the calculator and, observing the object on the monitor, combines the laser spot with the center of the desired control zone.

At the same time, the values of the current distance from the object to the x-ray emitter, calculated by the above formula, are displayed on the indicator of a television computer or computer display in real time.

After the end of the process of pointing the x-ray emitter at the object and determining the distance to it, x-raying of the control object is performed.

To increase the contrast of the image of laser spots in front of the lenses of digital cameras can be installed narrow-band filters, the passband of which corresponds to the laser radiation band.

Literature

1. Laser centralizer for x-ray emitter, RF patent No. 2235447.

Claims (1)

A laser centralizer for an x-ray emitter, comprising a housing with a laser disposed therein, whose axis is parallel to the longitudinal axis of the x-ray emitter, a plexiglass reflector mounted at the intersection of the laser and x-ray axes, a digital camera and a television computer or computer for determining the distance from the object to the x-ray emitter and a monitor, characterized in that an additional second and digital camera is introduced, similar to the first, the axis of the lens of which is parallel to the axis of the lens of the first digital camera and the axis of the x-ray beam, the lens axes of both digital cameras are located at a distance B from each other and lie in a plane formed by the axes of the laser and the x-ray beam, the axis of the lens of the first digital camera is located at a distance of 1≥t + A / 2 from the axis x-ray beam, where t = Δ · tg (α / 2), Δ is the distance from the focus of the x-ray emitter to the CCD matrix of the first digital camera of size A × A, α is the radiation angle of the x-ray emitter, both digital cameras are located at the same distance Δ, corner both the field of view of digital cameras having lenses with the same focal lengths f 'and identical CCD size A × A, correspond to the condition

and the calculated distance D from the object to the x-ray emitter is determined by the formula D = Δ + D ₀ , where

where P = X ₂ -X ₁ is the parallax of the images of the laser spot on the object coinciding with the point of intersection of the x-ray beam axis, X ₁ and X ₂ are the distances from the points of intersection of the axes of the lenses of the first and second digital cameras with the corresponding CCDs to the image laser spot on the CCD matrix of the first and second digital cameras, respectively.