KR100741575B1 - Fluorescence photographing apparatus which can decrease background - Google Patents

Abstract

A fluorescence photographing apparatus capable of decreasing background is provided to reflect the majority of image forming visible rays reflected by a reflective mirror and to prevent a background from being generated on an image. In a fluorescence photographing apparatus capable of decreasing background, background forming visible rays(12b) enter a reflective mirror(22) at an angle less than an angle(incident angle) of image forming visible rays(12a) formed by a normal line(24) of the reflective mirror, but a short wavelength transmission coating layer(60a) is formed on a reflective surface of the reflective mirror so that the background forming visible rays are not reflected by the reflective mirror. In order to absorb transmitting rays(12d), an absorbing painting layer(70) is formed on the rear surface of the reflective mirror. The transmission of the background forming visible rays through the reflective mirror is very effective with respect to the image forming visible rays of forming an incident angle greater than 45 degrees against the normal line of the reflective mirror.

Description

Fluorescence photographing apparatus which can decrease background}

1 is a view for explaining a conventional digital X-ray imaging apparatus;

2 and 3 are views for explaining a problem of the digital X-ray imaging apparatus of FIG.

4 is a view for explaining a digital x-ray imaging apparatus according to the present invention;

FIG. 5 is a graph for explaining the relationship of wavelength vs. transmittance with respect to the incident angle of the short wavelength transmission coating layer 60a.

<Description of reference numbers for the main parts of the drawings>

10: fluorescent screen 11: X-ray

12: visible light 12a: phase forming visible light

12b: Background forming scattered light 12c: Background forming scattered light

12d: transmitted light 13: water point

22: reflector 24: vertical normal

30: optical system 34: incident pupil

35: phase 35a: background

40: solid state image pickup device 50: microcomputer

60a: short wavelength transmission coating layer 60b: total reflection coating layer

70: absorbent coating layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescence imaging apparatus, and more particularly, to a fluorescence imaging apparatus for preventing a background from being generated by visible light reflected by a reflector.

X-ray imaging apparatus used to determine the patient's condition in the conventional hospital, environmental pollution caused by the lung solution generated when developing the X-ray film, the possibility of exposure of the patient by taking a number of pictures to diagnose the patient, and There are many problems such as excessive cost caused by long-term storage of the film. Therefore, recently, a digital X-ray imaging apparatus has been used to solve this problem.

Because digital X-rays store patient data on a computer, doctors can instantly view past X-ray film photos and print them out immediately if the patient desires. It also facilitates the transfer of data between hospitals located at distances and saves money by eliminating the need for a large space to store X-ray films for years. However, there are still many deficiencies in resolution and efficiency.

1 is a view for explaining a conventional digital X-ray imaging apparatus. Referring to FIG. 1, X-rays 11 transmitted through a human body among X-rays generated by an X-ray generator (not shown) are incident on the fluorescent screen 10 and are converted into visible light 12 by the fluorescent screen 10 and emitted. The visible light 12 emitted from the fluorescent screen 10 is reflected by the reflector 22 and is imaged on the solid state image pickup device CCD 40 through the optical system 30. The image input to the solid state image pickup device 40 is transferred to the computer 50.

2 and 3 are diagrams for describing a problem of the digital X-ray imaging apparatus of FIG. 1.

As shown in FIG. 2, the visible light 12 emitted from the fluorescent screen 10 is not only emitted in one direction but is scattered and emitted in various directions. Therefore, as shown in FIG. 3, the visible light 12 emitted from the fluorescent screen 10 enters the entrance pupil 34 of the optical system 30 and enters the light other than 12a which contributes to the formation of an accurate image 35. There is 12b that is scattered out of the copper 34 and contributes to the formation of the background 35a.

For example, when a very thin X-ray 11 stimulates a point on the fluorescent screen 10 to emit visible light, and this point forms the water point 13, the water point located at the center of the fluorescent screen 10 ( The image forming visible light 12a from 13 is incident on the reflecting mirror 22 in a straight line connecting the incident pupil 34 of the lens located virtually behind the reflecting mirror 22, and the background forming visible light 12b forms the image. The visible light 12a enters the upper portion of the reflector 22 (area close to the fluorescent screen) at an angle smaller than the incident angle θ2 formed with the reflector 22. The background forming visible light 12b is reflected toward the fluorescent screen 10 to illuminate other portions besides the water point 13 of the fluorescent screen 10. As a result, a bright background 35a is formed around the image 35 where visible light does not occur and should appear completely black.

On the other hand, even if the image-forming visible light 12a enters the upper part of the reflector (area close to the fluorescent screen) at an angle smaller than the incident angle θ2 formed with the reflector 22, the incident angle is not sufficiently small as indicated by reference numeral 12c. In this case, since the reflected light is directed to a place other than the fluorescent screen 10, the background 35a is not generated. The angle (incidence angle) of the light emitted from the lower portions 13-13b and the upper portions 13-13a of the fluorescent screen 10 with the vertical normal 24 of the reflector 24 is determined by the incident screen ( It changes according to the distance of 34).

As the example of the present invention, the optical device including the dark box should have a small size of the dark box in order to be easy to use and store, and a good example is a projection TV. In the case of a projection TV, a thin film becomes commercially available like a flat panel LCD or a PDP. Therefore, a wider angle of view of the optical system and a reflector are used to break the optical path. That is, in a general projection TV (including a liquid crystal), the optical system can be designed with a numerical aperture of 2.5 to 3.0 and an angle of view of about 90 degrees. Therefore, the optical lens and the reflector of such a wide angle are used together to reduce the thickness.

This is an important factor required in the fluorescence imaging apparatus. In order to widen the angle of view of the optical system, the distance from the fluorescent screen to the incident pupil of the lens is shortened, and the distance from the fluorescent screen to the reflector is as short as possible.

However, the fluorescence imaging apparatus has a requirement for the numerical aperture of the lens in addition to the demand for the angle of view. In other words, sufficient fluorescence should be collected from the fluorescent screen even at a weak X-ray intensity. This is because if the optical system does not sufficiently collect the fluorescence generated by the weak X-rays, it is inevitable to irradiate the strong X-rays on the fluorescent screen.

The amount received by the lens is proportional to the inverse of the square of the numerical aperture, and a large-diameter (less than 1.2 aperture) optical system with a small numerical aperture is used for the fluorescence imaging apparatus. However, the lens with a small numerical aperture that receives a lot of light has a large aberration correction burden, so it is impossible to design a very wide angle of view (about 90 degrees). Therefore, an angle of view of about 50 to 60 degrees is usually designed.

In the fluorescence imaging apparatus having such an optical system, the distance between the screen and the incident pupil of the lens should be short, and the reflector should be inserted to make the thickness thin, and the distance between the screen and the reflector should be short. At this time, as described above, a lot of phenomena in which the light reflected by the reflector is returned back to the fluorescent screen is reversed.

Accordingly, an object of the present invention is to provide a fluorescence photographing apparatus capable of preventing a background from being formed on a visible light reflected by a reflector.

According to an aspect of the present invention, a fluorescence imaging apparatus includes: a fluorescent screen for emitting fluorescence, a reflector for reflecting fluorescence emitted from the fluorescent screen in different directions, and an image of fluorescence reflected from the reflector A fluorescent imaging device comprising an imaging device,

A short wavelength transmissive coating layer is formed on the reflecting surface of the reflector such that the fluorescence which is reflected by the reflector to be returned to the fluorescent screen is transmitted through the reflector without being reflected by the reflector.

When the fluorescence imaging apparatus is used in the digital X-ray imaging apparatus, the fluorescence screen will receive X-rays and emit the fluorescence.

The short wavelength transmission coating layer may be formed on the entire surface of the reflecting surface of the reflector, but may be formed only on a portion thereof. When the short wavelength transmission coating layer is formed only in this way, it is preferable that the total reflection coating layer reflecting the fluorescence is formed on the remaining portion regardless of the incident angle.

The fluorescence emitted from the fluorescent screen may have a wavelength of 535 ~ 545nm, the wavelength band width is preferably 10nm ~ 30nm.

The fluorescent material of the fluorescent screen is preferably made of gadolinium sulfur oxide.

It is preferable that an absorption coating layer is formed on the back side of the reflector to absorb visible light passing through the reflector.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. Here, the same reference numerals as in the prior art denote components that perform the same function. The following examples are only presented to understand the content of the present invention, and those skilled in the art will be capable of many modifications within the technical spirit of the present invention. Therefore, the scope of the present invention should not be construed as limited to these embodiments.

4 is a view for explaining a digital X-ray imaging apparatus according to the present invention, in particular for explaining the reflector 22 which is a feature of the present invention. Referring to FIG. 4, the background forming visible light 12b is incident on the reflecting mirror 22 at an angle smaller than the angle θ2 (the incident angle) of the image forming visible light 12a with the vertical normal 24 of the reflecting mirror 22. The present invention is characterized in that the short wavelength transmission coating layer 60a is formed on the reflecting surface of the reflecting mirror 22 such that the background forming visible light 12b is not reflected by the reflecting mirror 22 and passes through the reflecting mirror 22. In addition, the present invention is characterized in that the absorption coating layer 70 is formed on the rear surface of the reflector 22 to absorb the transmitted light 12d passing through the reflector 22.

However, only the background forming visible light 12b is transmitted through the reflecting mirror 22 to diverge between the center 13 of the fluorescent screen and the upper portion 13a of the fluorescent screen, and the vertical normal 24 of the reflecting mirror 22 It is very effective for the image forming visible light 12a having a large angle of incidence of 45 degrees or more, but it is diverged between the center 13 of the fluorescent screen and the lower portion 13b of the fluorescent screen, and the vertical normal 24 of the reflector 22 It is not effective for the image forming visible light 12a having a small incident angle of 45 degrees or less.

This is because when the incident angle difference between the image-formed visible light 12a and the background-formed visible light 12b is small, the effect of separating transmission and reflection according to the incident angle is not properly exhibited. That is, a problem arises in that the phase-forming visible light 12a emitted between the center 13 of the fluorescent screen and the lower portion 13b of the fluorescent screen is not properly reflected by the short wavelength transmission coating layer 60 for background removal. .

However, the background forming effect is inversely proportional to the square of the distance from the water point to the point on the screen where the light from the water reaches, so that the center 13 of the fluorescent screen and the lower portion 13b of the fluorescent screen are far from the reflector 22. The background forming effect caused by the light emitted by the light emitting device is weak compared to the background forming effect caused by the light emitted between the center 13 of the fluorescent screen 13 and the upper portion 13a of the fluorescent screen, which are close to the reflector 22. . In addition, since light emitted between the center 13 of the fluorescent screen and the lower portion 13b of the fluorescent screen has a small incident angle incident on the reflector 22, the background is mainly generated by generating scattered light 12c that does not form a background. The effect that contributes to is very small.

Accordingly, the upper portion 22a of the reflector forms a short wavelength transmission coating layer 60a in which reflection and transmission are separated according to the incident angle, and the lower portion 22b of the reflector forms the total reflection coating layer 60b in which reflection is performed regardless of the incident angle. When formed, the upper portion 22a of the reflective mirror with severe background formation suppresses the background formation, and the lower portion 22b of the reflector having minimal background formation can faithfully transmit the light to the optical system 30 without loss of light. Can be. Of course, according to this, the absorption coating layer 70 may be formed only on the upper portion 22a of the reflector, not on the front surface of the reflector 22.

The size of the region of the short wavelength transparent coating layer 60a and the total reflection coating layer 60b may be adjusted according to the range of the incident angle since the incident angle changes according to the distance between the incident pupil 34 and the fluorescent screen 10.

FIG. 5 is a graph for explaining the relationship of wavelength vs. transmittance with respect to an angle of incidence of the short wavelength transmission coating layer 60a. When the incident light is incident on the reflector 22 at 50 degrees, at 45 degrees, at 20 degrees, and vertically, FIG. The case of incident is shown. As the short wavelength transmission coating layer 60a here, as shown in Table 1, one in which TiO 2 and SiO 2 were alternately laminated was used.

Table 1

 In order to form the short-wave transmissive coating layer 60a, various non-dielectric layers are vacuum coated, and the thickness of the coating material is alternately laminated with a thickness of 1/4 of a wavelength to be reflected. When light enters the short-wave transmissive coating layer 60a at an angle inclined instead of vertically incident, the optical path passing through the actual coating layer is increased by the inverse of the sine value of the incident angle, so that the wavelength for generating the same optical path is shortened.

The fluorescent material used for the fluorescent screen 10 can be selected as needed, for example, gadolinium sulfur oxide. Gadolinium sulfur oxide phosphors emit visible light (green) with a wavelength of 535-545 nm.

Referring to FIG. 5, it can be seen that in the wavelength range of 535 to 545 nm, the transmittance is mostly transmitted when the incidence angle is smaller than 20 degrees, and the transmittance is close to 0 and is mostly reflected when it is larger than 45 degrees. That is, when visible light emitted between the center 13 of the fluorescent screen and the upper portion 13a of the fluorescent screen has a wavelength in the range of 535 to 545 nm, the image forming visible light incident at an angle of 45 degrees or more is mostly reflected, but the background Most of the background-forming scattered light reflected at a small angle of incidence to form the light is transmitted and absorbed by the absorbing coating layer 70 on the rear surface of the reflector 22.

As described above, according to the present invention, it is possible to prevent the background from being generated by the scattered light while reflecting most of the phase-forming visible light reflected by the reflector 22.

Claims (7)

A fluorescence photographing apparatus comprising a fluorescence screen for emitting fluorescence, a reflector for reflecting fluorescence emitted from the fluorescence screen in a different direction, and an image forming apparatus for receiving and forming an fluorescence reflected by the reflector, And a short wavelength transmissive coating layer is formed on the reflecting surface of the reflector such that the fluorescence which is reflected by the reflector and is returned to the fluorescent screen is transmitted through the reflector without being reflected by the reflector. The fluorescence imaging apparatus according to claim 1, wherein the fluorescent screen receives the X-rays and emits the fluorescence. The fluorescence photographing apparatus according to claim 1, wherein a total reflection coating layer for reflecting the fluorescence is formed on the reflecting surface of the reflector with the short wavelength transmission coating layer regardless of the incident angle. The fluorescence imaging apparatus according to claim 1, wherein the fluorescence emitted from the fluorescent screen has a wavelength of 535 to 545 nm. The fluorescence imaging apparatus according to claim 1, wherein the wavelength band width of the fluorescence emitted from the fluorescent screen is 10 nm to 30 nm. The fluorescence imaging apparatus according to claim 1, wherein the fluorescent material of the fluorescent screen is made of gadolinium sulfur oxide. The fluorescence imaging apparatus according to claim 1, wherein an absorption coating layer is formed on a rear surface of the reflector to absorb visible light passing through the reflector.

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