CN209803029U - Combined Collimating Lens for CCD Cameras in Full-field X-ray Fluorescence Imaging - Google Patents

Abstract

A combined collimating lens for a CCD camera in full-field X-ray fluorescence imaging comprises a lens shell, a telescopic unit, a focal length adjusting knob, a pinhole collimator assembly, an X-ray window assembly and CCD camera coupling threads, wherein the pinhole collimator assembly and the X-ray window assembly are arranged in the telescopic unit in front and at the back and are used for collimating characteristic X-rays emitted from the surface of a sample and shielding visible light so as to realize full-field X-ray fluorescence imaging. The lens can ensure that the pinhole collimator and the CCD camera chip are parallel and coaxial, the shielding of visible light is ensured in multiple ways, the distance between the pinhole collimator and the sample and the CCD chip is effectively changed, the requirements of different analysis samples on different amplification rates are met, and the full-field X-ray fluorescence imaging effect and the system stability are improved.

Description

Combined Collimating Lens for CCD Cameras in Full-field X-ray Fluorescence Imaging

technical field

The utility model belongs to the field of X-ray fluorescence imaging, in particular to a combined collimation lens for a CCD camera in full-field X-ray fluorescence imaging, and is a kind of chemical element on the surface of a sample for CCD cameras used in full-field X-ray fluorescence imaging. Combination collimating lens for two-dimensional distribution.

Background technique

X-ray fluorescence (XRF) analysis is a relatively mature analytical technique for qualitative and quantitative analysis of elements in a sample and has many applications in various fields such as environment, archaeology, biological and forensic science, and industry. However, with the advancement of science and technology and the needs of scientific research, people want to study the spatial distribution of chemical elements in substances. X-ray fluorescence imaging is to irradiate the surface of the sample with primary X-rays generated by an excitation source such as an X-ray tube to generate characteristic X-rays corresponding to the element types, and use a detector to distinguish and record the energy (or wavelength), quantity and position of the characteristic X-rays information and thus image elements on the surface of the analyzed sample. Compared with some other research methods: electron probe X-ray microanalysis (EPMA), secondary ionization mass spectrometry (SIMS), etc., X-ray fluorescence imaging is non-destructive, does not require complicated sample pretreatment, and can be used for a variety of The advantages of analyzing morphological samples have good application and development prospects.

There are two commonly used implementation methods: micro-beam scanning method and full-field method. The micro-beam scanning method generally has high analysis precision, but it requires the sample to remain quite static and it requires a very long analysis time as the precision increases. In recent years, with the development of two-dimensional array detector CCD cameras, the pixel size has been reduced to 13 μm, and the use of matching collimators (microchannel plates, polycapillaries, pinholes, etc.) Area sample to be imaged. The thickness of the microchannel plate is generally about 1 mm, and the collimation effect is poor. Although polycapillary has high precision, it requires high technology and is expensive. In contrast, pinholes are cheap, easy to obtain and collimating to meet imaging requirements. At present, the pinhole collimator is installed at a fixed position at the front end of the CCD camera chip, and it is difficult to adjust the distance between the chip and the chip; or it is installed independently at the front end of the camera, and it is difficult to adjust the pinhole collimator to be parallel and coaxial with the chip. CCD cameras usually cooperate with optical lenses to capture visible light. When used in the X-ray field, X-ray windows must be used to block visible light and X-rays can pass through. Generally, expensive and toxic Be windows or A1 coated polymer films with high production requirements are used. , consider using cheap and readily available black polyimide film.

Therefore, for the CCD camera to be used for full-field X-ray fluorescence imaging, it must be equipped with a collimator and an X-ray window. Considering the disadvantages of the existing operation mode, the utility model designs a combination of the two and directly installs it on the CCD camera chip. Reliable lens on the front housing.

Utility model content

Aiming at the deficiencies in the prior art, the utility model provides a combined collimating lens for a CCD camera in full-field X-ray fluorescence imaging.

In order to achieve the above object, the utility model adopts the following technical solutions:

A combined collimating lens for a CCD camera in full-field X-ray fluorescence imaging, characterized in that it includes: a lens housing, a telescopic unit fastening screw, a focal length adjustment knob, a telescopic unit, a pinhole collimator assembly, a pinhole collimator Device assembly fastening ring, X-ray window assembly, X-ray window assembly fastening ring and CCD camera coupling thread; The rear end of the lens housing is provided with a CCD camera coupling thread for coupling with the CCD camera front housing; The telescopic unit is installed in the lens housing, and the focal length adjustment knob is connected to the lens housing and the telescopic unit, and is used to adjust the telescopic unit to move back and forth in the lens housing; the side of the lens housing is provided with threaded holes matching the fastening screws of the telescopic unit The telescopic unit is fastened by tightening the fastening screws of the telescopic unit; the pinhole collimator assembly is fixed on the front end of the telescopic unit through the pinhole collimator assembly fastening ring, and is used to orient the characteristic X-ray emitted by the sample The X-ray window assembly is fixed on the rear end of the telescopic unit through the X-ray window assembly fastening ring, which is used to block visible light but allow X-rays to pass through.

In order to optimize the above technical solutions, the specific measures taken also include:

Further, the focus adjustment knob is arranged around the telescopic unit, the telescopic unit is provided with an external thread, and the focus adjustment knob is provided with an internal thread matching the external thread of the telescopic unit; the rear end of the focus adjustment knob is provided with an annular protrusion, so that The annular protrusion is provided with an external thread, and the front end of the lens housing is provided with an internal thread matching the external thread of the annular protrusion.

Further, the external thread of the telescopic unit has a larger pitch than the external thread of the annular protrusion. By rotating the focal length adjustment knob, the telescopic unit moves back and forth in the lens housing, thereby changing the pinhole collimator assembly and the CCD Distance between camera chips.

Further, the front and rear ends of the telescopic unit are provided with stepped holes, and internal threads are provided in the stepped holes; the fastening ring of the pinhole collimator assembly is provided with an outer thread that matches the internal thread of the front stepped hole. screw thread, so that the pinhole collimator assembly is fixed in the stepped hole at the front end; the X-ray window assembly fastening ring is provided with an external thread that matches the internal thread of the rear end stepped hole, so that the X-ray window assembly is fixed in the stepped hole at the rear end.

Further, the pinhole collimator assembly includes a lower plate, a pinhole collimator, an upper plate and a shielding sheet arranged sequentially from back to front; the lower plate and the upper plate fix the pinhole collimator in the middle And ensure that it is parallel and coaxial with the CCD camera chip; the pinhole collimator directs the characteristic X-rays emitted by the sample surface to the CCD chip pixel array to obtain position information to realize full-field X-ray fluorescence imaging; The shield prevents the characteristic X-rays from passing through from other positions.

Further, the material of the lower plate and the upper plate is a hard polymer plastic plate; the pinhole diameter of the pinhole collimator is not greater than 50 μm, the thickness is equivalent to the pinhole diameter, and the material is a high atomic number element metal sheet; the shielding sheet The diameter of the hole in the center is 500 μm, the thickness is not less than 100 μm, and the material is a high atomic number element metal sheet.

Further, the X-ray window assembly includes an inner ring, a black polyimide film and an outer ring; the inner ring and the outer ring are nested with each other for fixing the black polyimide film and ensuring its flatness; the Black polyimide film is used to block visible light but allow X-rays to pass through.

Further, the inner and outer rings are made of flexible polymer plastic plates; the thickness of the black polyimide film is 50 μm.

The beneficial effects of the utility model are: the utility model connects the lens housing and the telescopic unit through the focal length adjustment knob and adjusts the telescopic unit to move back and forth in the lens housing, and integrates the X-ray window assembly and the pinhole collimator assembly at the rear end of the telescopic unit and the front end to form a compact combined lens, which can not only block visible light and collimate the characteristic X-rays emitted by the sample to obtain position information, but also facilitate the adjustment of the focal length to realize large-scale and rapid analysis of the two-dimensional distribution of elements on the sample. imaging studies. Using a black polyimide film with a thickness of 50 μm can effectively block visible light but allow X-rays to pass through. Installing the pinhole collimator directly on the front of the CCD camera through a fixed component can effectively ensure that the pinhole collimator is in good contact with the CCD camera. The CCD camera chip is parallel and coaxial, which greatly improves the collimation effect and the certainty of the test area on the analysis sample. Controlling the telescopic unit to move back and forth through the focus adjustment knob can effectively change the distance between the pinhole collimator and the CCD camera chip and the analysis sample. In order to change the magnification of the full-field X-ray fluorescence imaging system to meet the imaging requirements of different test areas. At the same time, the shielding sheet in the pinhole assembly is a thicker metal sheet with high atomic number elements and a slightly larger aperture, which can effectively shield higher energy X-rays so that the characteristic X-rays emitted by the sample can only pass through the pinhole. Improve the accuracy of photon position information and the stability of imaging systems. In addition, the pinhole collimator and the shielding sheet are located at the front of the X-ray window, which block most of the visible light at first, and cooperate with the black polyimide film to provide multiple guarantees for blocking visible light.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the utility model.

Figure 2 is a schematic diagram of a pinhole collimator assembly.

Fig. 3 is a schematic diagram of an X-ray window assembly.

Fig. 4 is the XRF spectrogram in the embodiment of the utility model.

Fig. 5 is a two-dimensional distribution diagram of sample elements in the embodiment of the present utility model.

Reference signs are as follows: lens housing 10, telescopic unit fastening screw 20, focus adjustment knob 30, telescopic unit 40, pinhole collimator assembly 50, pinhole collimator assembly fastening ring 60, X-ray window assembly 70, X-ray window assembly fastening ring 80, CCD camera coupling thread 90, annular protrusion 301, lower plate 501, pinhole collimator 502, upper plate 503, shielding sheet 504, inner ring 701, black polyimide film 702 , Outer Ring 703.

Detailed ways

Now in conjunction with accompanying drawing, the utility model is described in further detail.

As shown in Figure 1, the combined collimating lens for CCD camera in the full-field X-ray fluorescence imaging includes the following structure: lens housing 10, telescopic unit fastening screw 20, focal length adjustment knob 30, telescopic unit 40, pinhole collimator Collimator assembly 50 , pinhole collimator assembly fastening ring 60 , X-ray window assembly 70 , X-ray window assembly fastening ring 80 , CCD camera coupling thread 90 .

Among them, the focal length adjustment knob 30 is used to connect the lens housing 10 and the telescopic unit 40 and adjust the telescopic unit 40 to move back and forth in the lens housing 10; the telescopic unit fastening screw 20 is used to fasten the telescopic unit 40; the telescopic unit 40 has two positions The stepped holes are respectively used to place the pinhole collimator assembly 50 and the X-ray window assembly 70; the pinhole collimator assembly fastening ring 60 is used to fix the pinhole collimator assembly 50; the pinhole collimator assembly 50 is used for Guide the characteristic X-rays emitted by the sample to the pixel array of the CCD camera chip to obtain position information; the X-ray window assembly fastening ring 80 is used to fix the X-ray window assembly 70; the X-ray window assembly 70 is used to block visible light but X Rays can pass through; the CCD camera coupling thread 90 is used for coupling connection with the front shell of the CCD camera. The lens can ensure that the pinhole collimator is parallel and coaxial with the CCD camera chip, multiple guarantees to shield visible light, effectively change the distance between the pinhole collimator, the sample and the CCD chip, and meet different analysis samples with different magnifications In order to improve the effect of full-field X-ray fluorescence imaging and the stability of the system.

The focal length adjustment knob 30 connects the lens housing 10 and the telescopic unit 40 through the coupling thread, and the telescopic unit 40 moves back and forth in the lens housing 10 by rotating the focal length adjustment knob 30, changing the distance between the pinhole collimator 502 and the CCD camera chip, and tightening The telescopic unit fastening screw 20 fixes the position. Both the front end and the rear end of the telescopic unit 40 are provided with stepped holes with internal threads, and the pinhole collimator is screwed into the pinhole collimator assembly fastening ring 60 and the X-ray window assembly fastening ring 80 with external threads to make the pinhole collimator The component 50 and the X-ray window component 70 are respectively fixed between the stepped holes and the fastening rings at the front and rear ends of the telescopic unit 40 .

As shown in FIGS. 2 a , 2 b , and 2 c , the pinhole collimator assembly 50 includes a lower plate 501 , a pinhole collimator 502 , an upper plate 503 and a shielding sheet 504 . The lower plate 501 and the upper plate 503 are used to fix the pinhole collimator 502 and ensure that it is parallel and coaxial with the CCD camera chip, and are made of hard polymer plastic plates such as polyether ether ketone (PEEK). The pinhole collimator 502 is used to direct the characteristic X-rays emitted by the sample surface to the pixel array of the CCD chip to obtain position information to realize full-field X-ray fluorescence imaging. The diameter of the pinhole is not more than 50 μm, and the thickness is equivalent to the diameter of the pinhole , the material is metal sheets of high atomic number elements such as tungsten W and lead Pb. The shielding sheet 504 is used to prevent the characteristic X-rays from passing through from other positions. The diameter of the hole is about 500 μm, the thickness is not less than 100 μm, and the material is metal sheets with high atomic number elements such as tungsten W and lead Pb.

As shown in FIG. 3 , the X-ray window assembly 70 includes an inner ring 701 , a black polyimide film 702 and an outer ring 703 . The inner ring 701 and the outer ring 703 are nested with each other to fix the black polyimide film 702 and ensure its smoothness. The material is a soft polymer plastic plate such as polyoxymethylene POM, and the color is black. The black polyimide film 702 is used to block visible light but allow X-rays to pass through, with a thickness of about 50 μm.

The pinhole collimator assembly 50 is located on the sample surface side of the front end of the lens, and the X-ray window assembly 70 is located on the side of the CCD camera chip at the rear end of the lens. The shielding sheet 504 and the pinhole collimator 502 block most of the visible light at first. Black polyimide film 702 provides multiple guarantees for blocking visible light.

Example 1: A combined sample of one side zirconium (Zr) metal and one side molybdenum (Mo) metal

Zr is element 40, K absorption limit is 17.998keV, K _α characteristic X-ray energy is 15.774keV, K _β characteristic X-ray energy is 17.666keV; Mo is element 42, K absorption limit is 20.002keV, K _α characteristic X The ray energy is 17.478keV, and the _Kβ characteristic X-ray energy is 19.607keV. Zr and Mo metal blocks with a side length of 50 mm and a thickness of 5 mm were erected side by side on the sample stage.

According to the structural schematic diagram shown in Figure 1, the above-mentioned technical scheme is used to equip a combined collimating lens for imaging the Zr and Mo metal interface.

In this embodiment, the distance between the pinhole collimator 502 and the CCD camera chip can be changed between 43 mm and 49.7 mm by turning the focus adjustment knob 30 to adjust the telescopic unit 40 to move back and forth; in the pinhole collimator assembly 50: The lower plate 501 has an outer diameter of 25 mm, an inner diameter of 15 mm, a thickness of 2 mm, and a step height of 1 mm. The material is polyetheretherketone (PEEK) plastic plate. The pinhole collimator 502 has a diameter of 20 mm, a thickness of 50 μm, and a central pinhole diameter of 50 μm. The material is Tungsten metal sheet, the upper plate 503 has an outer diameter of 20mm, an inner diameter of 15mm, and a thickness of 1mm, and is made of polyetheretherketone (PEEK) plastic plate. The shielding sheet 504 has a diameter of 25mm, a thickness of 100μm, and a central hole diameter of 500μm, and is made of a tungsten metal sheet; In the X-ray window assembly 70: the inner ring 701 has an outer diameter of 12.7 mm, an inner diameter of 11.7 mm, a thickness of 1 mm, and a height of 11 mm, and is made of polyoxymethylene (POM) plastic plate; 1mm, 11mm high, made of polyoxymethylene (POM) plastic plate, black polyimide film 702 with a thickness of 50 μm.

The magnification M of the full-field X-ray fluorescence imaging system is the ratio of the pinhole-CCD camera chip distance L1 to the pinhole-sample surface distance L2, as shown in _formula ( ₁ ):

In this embodiment, both L ₁ and L ₂ are 45 mm, and the magnification M is 1.

Use the lens designed and equipped by the utility model to carry out full-field X-ray fluorescence imaging on the Zr and Mo metal interface, the W target X-ray tube works under 40kV-800μA, and the exposure time of the CCD camera is 200s, and the image obtained by exposing 20 times is carried out Data processing obtained the X-ray fluorescence spectrum shown in Figure 4 and the two-dimensional distribution image of sample elements shown in Figure 5 (Zr Kβ characteristic X-ray energy overlaps with Mo Kα, so Zr Kα characteristic X-ray and Mo Kβ characteristic X rays for position resolution). It can be seen that the utility model can make the CCD camera work effectively in the X-ray energy range and effectively collimate the characteristic X-rays emitted by the sample, making the whole-field X-ray fluorescence imaging more reliable and convenient.

It should be noted that terms such as "upper", "lower", "left", "right", "front", and "rear" cited in the utility model are only for the convenience of description and are not used In order to limit the applicable scope of the present utility model, the change or adjustment of the relative relationship shall also be regarded as the applicable scope of the present utility model without substantive changes in the technical content.

The above are only preferred implementations of the utility model, and the scope of protection of the utility model is not limited to the above-mentioned embodiments, and all technical solutions under the thinking of the utility model all belong to the scope of protection of the utility model. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications without departing from the principle of the utility model should be regarded as the protection scope of the utility model.

Claims (8)

1. A combined collimating lens for a CCD camera in full-field X-ray fluorescence imaging, characterized in that it includes: a lens housing (10), a telescopic unit fastening screw (20), a focal length adjustment knob (30), a telescopic unit ( 40), pinhole collimator assembly (50), pinhole collimator assembly fastening ring (60), X-ray window assembly (70), X-ray window assembly fastening ring (80) and CCD camera coupling thread ( 90); the rear end of the lens housing (10) is provided with a CCD camera coupling thread (90) for coupling with the front housing of the CCD camera; the telescopic unit (40) is installed in the lens housing (10), the The focal length adjustment knob (30) is connected to the lens housing (10) and the telescopic unit (40), and is used to adjust the telescopic unit (40) to move back and forth in the lens housing (10); the side of the lens housing (10) is provided with the telescopic unit The threaded hole that the fastening screw (20) matches, the telescopic unit (40) is fastened by tightening the fastening screw (20) of the telescopic unit; the pinhole collimator assembly (50) passes through the pinhole collimator The component fastening ring (60) is fixed on the front end of the telescopic unit (40), and is used to direct the characteristic X-rays emitted by the sample to the pixel array of the CCD chip to obtain position information; the X-ray window component (70) passes through The fastening ring (80) of the X-ray window assembly is fixed on the rear end of the telescopic unit (40), and is used for blocking visible light but allowing X-rays to pass through. 2. The combined collimating lens for CCD cameras in full-field X-ray fluorescence imaging according to claim 1, characterized in that: the focal length adjustment knob (30) is arranged around the telescopic unit (40), and the telescopic unit (40 ) is provided with an external thread, and the focus adjustment knob (30) is provided with an internal thread that matches the external thread of the telescopic unit (40); the rear end of the focus adjustment knob (30) is provided with an annular protrusion (301), and the annular The protrusion (301) is provided with an external thread, and the front end of the lens housing (10) is provided with an internal thread matching the external thread of the annular protrusion (301). 3. The combined collimating lens for CCD cameras in full-field X-ray fluorescence imaging according to claim 2, characterized in that: the external thread of the telescopic unit (40) is compared with that of the annular protrusion (301). The external thread has a large pitch, and by rotating the focal length adjustment knob (30), the telescopic unit (40) moves back and forth in the lens housing (10), thereby changing the distance between the pinhole collimator assembly (50) and the CCD camera chip . 4. The combined collimating lens for CCD cameras in full-field X-ray fluorescence imaging according to claim 1, characterized in that: the front and rear ends of the telescopic unit (40) are provided with stepped holes, inside the stepped holes Both are provided with internal threads; the pinhole collimator assembly fastening ring (60) is provided with external threads that match the internal threads of the front stepped hole, so that the pinhole collimator assembly (50) is fixed on the front end In the stepped hole; the X-ray window component fastening ring (80) is provided with an external thread matching the internal thread of the rear-end stepped hole, so that the X-ray window component (70) is fixed in the rear-end stepped hole. 5. The combined collimating lens for CCD cameras in full-field X-ray fluorescence imaging according to claim 1, characterized in that: the pinhole collimator assembly (50) includes lower plate (501), pinhole collimator (502), upper plate (503) and shielding sheet (504); the lower plate (501) and upper plate (503) fix the pinhole collimator (502) on In the middle and ensure that it is parallel and coaxial with the CCD camera chip; the pinhole collimator (502) directs the characteristic X-rays emitted from the sample surface to the pixel array of the CCD chip to obtain position information to realize full-field X-ray fluorescence imaging. 6. The combined collimating lens for CCD cameras in full-field X-ray fluorescence imaging according to claim 5, characterized in that: the lower plate (501) and the upper plate (503) are made of hard polymer plastic plate; the pinhole diameter of the pinhole collimator (502) is not greater than 50 μm, the thickness is equivalent to the pinhole diameter, and the material is a high atomic number element metal sheet; the diameter of the hole in the center of the shielding sheet (504) is 500 μm, and the thickness is not less than 100 μm , the material is high atomic number element metal sheet. 7. The combined collimating lens for CCD cameras in full-field X-ray fluorescence imaging according to claim 1, characterized in that: the X-ray window assembly (70) includes an inner ring (701), black polyimide The amine film (702) and the outer ring (703); the inner ring (701) and the outer ring (703) are nested with each other to fix the black polyimide film (702) and ensure its flatness; the black polyimide film (702) is The imide film (702) is used to block visible light but ensure that X-rays can pass through. 8. The combined collimating lens for CCD cameras in full-field X-ray fluorescence imaging according to claim 7, characterized in that: the inner ring (701) and outer ring (703) are made of flexible polymer plastic plates ; The thickness of the black polyimide film (702) is 50 μm.