JP2002072380A - Light convergence optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the efficiency of light convergence of emitted light or transmitted light from a body having been irradiated within a linear irradiation range whose width is shorter than the length and to make a device small-sized. SOLUTION: A light convergence area A is divided into light convergence areas A1, B1, A2, B2... of length (r) along the length (arrow X) direction; and condenser lenses a1, a2... which have an external diameter (d) (d=wr>; r) along the length (arrow X) of the light convergence area to converge emitted or transmitted lights from the light convergence areas A1, A2... on a photodetection part and (n) (n>=w=d/r>;1) columns of condenser lens b1, b2... having an external diameter 8d are arranged along the width (arrow Y) of the light convergence area to converge emitted or transmitted lights from the light convergence areas B1, B2... on the photodetection part. Then the opening ratio of the condensing lenses are made large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condensing optical system, and more particularly, to a condensing optical system for condensing emitted light or transmitted light from an object irradiated with irradiation light. .

[0002]

2. Description of the Related Art Conventionally, light emitted or transmitted from an object which has been irradiated to a long and narrow irradiation range with irradiation light is received by a light receiving section (line sensor) composed of a photoelectric conversion element or the like, and the received light signal is electrically transmitted. 2. Description of the Related Art A technique for converting an image into a signal and performing image processing to obtain an image signal of an irradiated portion of an object is widely used. A light source and a light receiving portion of the irradiation light, and one of the objects is moved (scanned) relatively to the other, and the light signals from the respective positions of the object corresponding to the movement are sequentially received to perform photoelectric conversion. A system for obtaining an image signal of an entire object is realized by a printing machine, a copying machine, a facsimile, or the like.

In the field of radiation image information reading, when radiation is irradiated, a part of the radiation energy is accumulated, and subsequently, when irradiated with excitation light such as visible light or laser light, the accumulated radiation energy is irradiated. Using a stimulable phosphor (stimulable phosphor) that emits stimulable light in response to a subject, a stimulable phosphor sheet is formed by laminating a stimulable phosphor on a support, and an object such as a human body is placed on the sheet. The excitation light such as laser light is deflected and scanned for each pixel on the radiation image information once accumulated and recorded, and stimulated emission light is sequentially generated from each pixel, and the stimulated emission light is photoelectrically scanned by photoelectric reading means. A radiation image recording / reproducing system for sequentially irradiating the stimulable phosphor sheet after reading the image signal with an erasing light to emit radiation energy remaining on the sheet. Beam (Computed Radiography = C
R) is also widely used in practice.

The image signals obtained by these systems are subjected to image processing such as gradation processing and frequency processing suitable for observation and interpretation, and the image signals after these processings are applied to a diagnostic visible image. (Final image) recorded on film,
Alternatively, it is displayed on a high-definition CRT and used for diagnosis by a doctor or the like. On the other hand, when the stimulable phosphor sheet is irradiated with erasing light to release residual energy, the sheet can again store and record radiation image information, and can be used repeatedly.

Here, in the radiation image information reading apparatus used in the above-mentioned radiation image recording and reproducing system,
A line light source that linearly irradiates the sheet with excitation light is used as the excitation light source, and the length of the linear portion of the sheet irradiated with the excitation light by the line light source (hereinafter referred to as the main light source) is used as photoelectric reading means. Along with a line sensor in which a large number of photoelectric conversion elements are arranged along the scanning direction.
A direction substantially perpendicular to the length direction of the linear portion, with one of the line light source and the line sensor and the phosphor sheet relative to the other (hereinafter, referred to as a sub-scanning direction)
Japanese Patent Application Laid-Open Nos. 60-111568, 60-236354, 1-101540 and the like have been proposed.

[0006] In these systems, linear excitation and linear reading are realized using a line light source and a line sensor, so that the reading time of stimulated emission light can be shortened, and the apparatus can be reduced in size and cost. And so on.

[0007]

However, light emitted from the object irradiated with the irradiation light (stimulated emission light when the object is a stimulable phosphor sheet) or transmitted light is transmitted to the light receiving section (line sensor). The light-collecting efficiency of the light-collecting optical system for collecting light is one of the major factors that determine the quality of an image. However,
In the above-described system, as shown in FIG. 1, in order to achieve good imaging performance over the scanning end with one set of lenses, it is necessary to increase the distance between the condenser lens and the object. There is a problem that the whole becomes large and the light collection efficiency is lowered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a light-collecting optical system that increases the light-collecting efficiency for collecting light emitted from or transmitted from an object and reduces the size of the device. It is intended for.

[0009]

According to the present invention, there is provided a light-collecting optical system for collecting light emitted or transmitted from an object irradiated in an irradiation area having a width shorter than the length. A plurality of rows of condensing lenses provided in the length direction and the width direction, respectively, in a range, wherein an outer diameter (d) of each of the condensing lenses in the length direction is the object. Is n times or less the length (r) of the light emission or transmission region (similar to the irradiation range) of light condensed by one condensing lens on the irradiated surface, and n Is an integer greater than 1 and is equal to the number of rows of the condenser lens in the width direction.

That is, as shown in FIG. 2, the light-collecting area A shown in FIG.
1, B1, A2, B2,. . . Instead of condensing the emitted light or transmitted light from the condensing area A with one set of condensing lenses a, a plurality of columns are arranged in the length direction (arrow X direction) and the width direction (arrow Y direction). Condenser lenses a1, b1, a
2, b2,. . . Are used to collect light converging areas A1, B1, and A, respectively.
2, B2. . . The emitted light or transmitted light from is collected on the light receiving unit.

Here, each condenser lens a1, b1, a2,
b2,. . . Let d be the outer diameter of each light-collecting area A1, B1,
A2, B2,. . . If the length of r is r, the relationship between d and r and the number of rows n of the condenser lens can be expressed by the following equation (1).

1 <d / r = w ≦ n (1) where n is an integer greater than 1.

That is, in the condensing optical system according to the present invention, the outer diameter d of each condensing lens is larger than the length r of the converging region and is w times (w> 1) the length r of the converging region. Are arranged in the length direction (arrow X direction), and these condenser lenses are arranged in n rows (n ≧ w) in the arrow Y direction.

FIG. 2 shows only two converging lenses in the width direction (arrow Y direction) of the converging area, but the number n of converging lenses is a multiple w (w = d / r). Any number of larger integers (that is, as long as the relationship of Expression (1) is satisfied) may be arranged. However, from the viewpoint of miniaturization and cost reduction of equipment,
It is desirable that the number of columns n be an integer as close as possible to a multiple w (w = d / r).

[0015] In this condensing optical system, the object is a stimulable phosphor sheet in which radiographic image information is accumulated, and the emitted light is an excitation light that is linearly applied to the stimulable phosphor sheet. A device which is stimulated emission light emitted from the irradiated portion by excitation or the backside portion of the stimulable phosphor sheet corresponding to the irradiated portion, that is, a radiation image using the stimulable phosphor sheet In information reading devices,
It functions as a condensing means for stimulating light, and can increase the light-condensing efficiency for condensing the stimulating light on a line sensor or the like.

[0016]

According to the condensing optical system according to the present invention, light emitted or transmitted from an object irradiated in a linear irradiation range (light condensing area) having a width shorter than its length, in other words, In order to condense light, as shown in FIG. 2, the light-converging area A is converged in the length direction (arrow X direction) with light-converging areas A1, B1, and A having a length r.
2, B2,. . . And the length direction of the focusing area (arrow X)
Condensing lens a having a plurality of outer diameters d (d = wr> r)
1, a2,. . . And condensing areas A1 and A
2,. . . Light or transmitted light from the light-receiving portion is condensed on the light-receiving portion, and n columns (n
≧ w = d / r> 1) condensing lenses b1, b having an outer diameter d
2,. . . Are arrayed, and the light-collecting regions B1, B2,. . .
Since the emitted light or transmitted light from is focused on the light receiving portion, the outer diameter d of each focusing lens is larger than the length r of the focusing region in which the focusing lens is responsible for focusing. The aperture ratio of each condensing lens can be kept large, the condensing efficiency can be increased, and the size of the device can be reduced.

Further, the condensing optical system according to the present invention is used in a radiation image information reading apparatus using a stimulable phosphor sheet, and the stimulated emission light from the stimulable phosphor sheet is condensed on a light receiving portion such as a line sensor. If it is applied as a light-collecting means, the size of the device can be reduced, and the light-collecting efficiency of stimulated emission light can be increased, so that a high-quality radiation image can be obtained.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a condensing optical system according to an embodiment of the present invention.

The condensing optical system according to the present invention is shown in FIG. 2 for condensing emitted light or transmitted light from an object irradiated in an irradiation range (condensing area) having a width shorter than the length. As described above, the light-converging region A has a length r in the length direction (the direction of the arrow X).
Of light-collecting regions A1, B1, A2, B2,. . . And a plurality of outer diameters d (d = d
wr> r) condensing lenses a1, a2,. . . Are arrayed, and the light-collecting regions A1, A2,. . . And condensed light transmitted through the light condensing lens b1 having an outer diameter d of n rows (n ≧ w = d / r> 1) in the width direction (arrow Y direction) of the light condensing area. , B2,. . . And condensing area B respectively
1, B2,. . . To condense the emitted light or transmitted light from the light-receiving section to increase the light-condensing efficiency of the emitted light or transmitted light from the light-condensing area A. Can be applied. FIG. 3 is a perspective view showing a radiation image information reading apparatus 100 using a stimulable phosphor sheet in which the condensing optical system according to the present invention is applied as a means for condensing stimulated emission light, and FIG. 4 is shown in FIG. FIG. 5 is a cross-sectional view showing a cross section taken along line II of the radiation image information reading apparatus 100.
FIG. 3 is a diagram showing details of a line sensor 20 serving as a light receiving unit of the radiation image information reading apparatus 100 and a light collecting optical system 16 for collecting stimulated emission light on the line sensor 20.

The radiation image information reading apparatus 100 shown in FIG.
A scanning belt 40 on which a stimulable phosphor sheet (hereinafter, referred to as a sheet) 50 on which radiation image information is stored and conveyed in the arrow Y direction, a linear 2 having a line width of about 100 μm.
BLD 11 and BLD that emit secondary excitation light (hereinafter simply referred to as excitation light) L at an angle of approximately 45 degrees with respect to the surface of sheet 50
An optical system 12 for irradiating the linear excitation light L to the surface of the sheet 50, comprising a combination of a collimator lens for condensing the linear excitation light L emitted from 11 and a toric lens for expanding the beam only in one direction; The photostimulated luminescence light M emitted from the sheet 50 by the irradiation of the excitation light L has an optical axis that is inclined by approximately 45 degrees with respect to the surface of the excitation light L and is substantially perpendicular to the direction in which the excitation light L travels. The condensing optical system 16 for condensing light on the light receiving surface of each photoelectric conversion element 21 constituting the line sensor 20, and the respective condensing lenses a1, b1, c1,. . . Light cut filter 1 for cutting excitation light L mixed with stimulated emission light M emitted from
7. Stimulated light M transmitted through the excitation light cut filter 17
A line sensor 20 in which a large number of photoelectric conversion elements for receiving and photoelectrically converting the signal are arranged, and a signal S obtained by reading a signal output from each of the photoelectric conversion elements 21 constituting the line sensor 20 is referred to as a read portion of the sheet 50. An image information reading means 30 for outputting the image information to the image processing apparatus is provided.

As shown in FIG. 5, the line sensor 20 has a large number (for example, 1000) of photoelectric conversion elements 21 in the direction of the arrow X corresponding to each of the condenser lenses constituting the condenser optical system 16. As described above), they are arranged in three rows of 20a, 20b, 20c in the direction of the arrow Y. Specifically, as the photoelectric conversion element 21, an amorphous silicon sensor, a CCD or a MOS image sensor, or the like can be applied.

Further, as shown in FIG.
Are the respective light condensing areas A1, B1, and E on the sheet 50.
1, A2, B2, E2,. . . A plurality of condensing lenses having an outer diameter d that is three times the length r in the arrow X direction are arranged in the arrow X direction, and are also arranged in three rows in the arrow Y direction. Each of the condensing lenses has a function of forming, on the light receiving surface of each of the photoelectric conversion elements 21, an image plane on which the respective light-emitting regions of the photostimulated light M on the sheet 50 are formed in a one-to-one size. Further, the optical system 12 including the collimator lens and the toric lens expands the excitation light L from the BLD 11 on the sheet 50 to a desired irradiation area.

Next, the operation of the radiation image information reading apparatus 100 to which the condensing optical system according to the present invention is applied will be described.

First, by moving the scanning belt 40 in the direction of arrow Y, the scanning belt 40
The sheet 50 on which the radiation image information is stored is conveyed in the direction of arrow Y. At this time, the conveying speed of the sheet 50 is equal to the moving speed of the belt 40, and the moving speed of the belt 40 is input to the reading unit 30.

On the other hand, the BLD 11 emits a linear excitation light L having a line width of approximately 100 μm in a direction inclined at an angle of approximately 45 degrees with respect to the surface of the sheet 50, and the excitation light L is projected on the optical path. The beam is converted into a parallel beam by the optical system 12 including a collimator lens and a toric lens provided, and is incident on the sheet 50 at an angle of approximately 45 degrees with respect to the surface of the sheet 50. At this time, the excitation light L irradiates a linear (line width d _L approximately 100 μm) region extending along the arrow X direction (the direction perpendicular to the paper surface in FIG. 4) on the surface of the sheet 50.

The linear excitation light L incident on the sheet 50 is
As the vicinity of the irradiated region (line width d _L shown 100 [mu] m) and the irradiation zone, emit stimulated emission M having an intensity corresponding to the radiation image information recorded therein. The stimulating light M
Is incident on the condensing optical system 16 and is condensed on the light receiving surface of each corresponding photoelectric conversion element 21 by each condensing lens of the condensing optical system 16. That is, the condenser lenses a1 and a1 in the 16a row
2, a3,. . . Are emission areas A1, A2, and A, respectively.
3,. . . The stimulating light emitted from the lens is condensed on the corresponding photoelectric conversion elements 21 in the 20a row of the photoelectric conversion elements of the line sensor 20, and the condensing lenses b1, b2, b in the 16b row
3,. . . Are light-emitting areas B1, B2, B3,. . . Photostimulated light from the photoelectric conversion element 2 of the line sensor 20
The light is condensed on the corresponding photoelectric conversion elements 21 in the 0b row,
The condensing lenses e1, e2, e3,. . . Are the emission ranges E1, E2, E3,. . . Stimulating light emitted from the photoelectric conversion element is condensed on the photoelectric conversion elements 21 corresponding to the 20e rows of the photoelectric conversion elements of the line sensor 20. The stimulated emission light M condensed by the condensing optical system 16 passes through the excitation light cut filter 17 before entering the line sensor 20, and the mixed excitation light L is cut.

On the other hand, the line sensor 20 photoelectrically converts the stimulated emission light M received by each photoelectric conversion element 21,
The image information is read from each signal S obtained by photoelectric conversion by the reading unit 3.
0 is output to an external image processing device or the like in association with the part of the sheet, and is used for reproducing a diagnostic image.

In this embodiment, for the sake of simplicity, each condenser lens of the condenser optical system 16 between the sheet 50 and the line sensor 20 is set to a 1: 1 image forming system. Is provided so as to face each of the condensing lenses and the respective photoelectric conversion elements 21 constituting the line sensor 20 on a one-to-one basis.
That is, one condensing lens (for example, a1) condenses stimulated emission light M emitted from a condensing area (A1 in the case of a1) in the sheet 50 of the condensing lens onto one photoelectric conversion element 21. If such a configuration is adopted, a scaling lens may be used.

Here, for convenience of explanation, three rows of condenser lenses are arranged in the direction of the arrow Y, and each condenser lens emits stimulated emission light from a condensing area of one third of its outer diameter. Although it is set so as to collect light, the number 3 of columns is merely an example, and from each practical condition, the number n of columns of the condenser lens can be arbitrarily determined as long as Expression (1) is satisfied. Of course.

As described above, the radiation image information reading apparatus 100 in which the condensing optical system according to the present invention is applied as a condensing means for stimulated emission light has a condensing optical system 16 having an outer diameter d in the arrow Y direction. A plurality of condenser lenses are arranged in three rows (16a, 16b,
16c) The condensing lenses of each row are arranged and the condensing areas A * (*: 1,
2, 3,. . . ), B * (*: 1, 2, 3, ...),
Since the light emitted from E * (*: 1, 2, 3,...) Is condensed on the corresponding photoelectric conversion element 21 of the line sensor 20 serving as the light receiving unit, Since the outer diameter d is larger than the length r of the light-collecting region where the light-collecting lens performs light-gathering, the aperture ratio of each light-collecting lens can be kept large, and the light-gathering efficiency is increased and the size of the device is reduced. Can be achieved. Therefore, a high quality radiation image can be obtained with a compact apparatus.

The radiation image information reading device 100
Is a reflected light condensing type configuration in which both a light source for excitation light and a line sensor are arranged on the same surface side of the sheet to receive stimulated emission light emitted from the sheet surface on which the excitation light is incident. However, the condensing optical system of the present invention can be applied not only to such a configuration, but also by using a stimulable phosphor sheet in which a support is formed of a photostimulable light-transmitting material. As shown in FIG. 6, a light source for excitation light and a line sensor are arranged on different sides of a sheet to receive stimulated emission light emitted from a surface opposite to the sheet surface on which the excitation light is incident. The present invention can be applied to the radiation image information reading apparatus 200 having the configuration of the transmitted light condensing type.

That is, the illustrated radiation image information reading device 2
Reference numeral 00 denotes the front end and the rear end of the stimulable phosphor sheet 50 (the front end and the rear end do not have a radiographic image recorded, or have a radiographic image recorded but not a region of interest). A conveying belt 40 'that supports and conveys the sheet in the direction of the arrow Y, a BLD 11 that emits linear excitation light L in a direction substantially orthogonal to the surface of the sheet 50, and a collection of linear excitation light L emitted from the BLD 11. An optical system 12 for irradiating a linear excitation light L on the surface of the sheet 50, comprising an optical system that irradiates a linear excitation light L on the surface of the sheet 50, comprising a combination of a collimator lens that emits light and a toric lens that expands the beam in only one direction, The stimulated emission light M ′ emitted from the back surface of the sheet 50 (the surface opposite to the incident surface of the excitation light L) by the irradiation of the excitation light L is used as the light receiving surface of each photoelectric conversion element 21 constituting the line sensor 20. A condensing optical system 16 for condensing light, an excitation light cut filter 17 for cutting excitation light L mixed in the stimulable light M ′ incident on each photoelectric conversion element 21, and a stimulable light transmitted through the excitation light cut filter 17. A line sensor 20 in which a large number of photoelectric conversion elements 21 for receiving M ′ and performing photoelectric conversion are arranged, and an image information reading means 30 for outputting a signal output from each photoelectric conversion element 21 constituting the line sensor 20. It is a configuration provided. As the line sensor and the condensing optical system, the configuration as shown in FIG. 5 is applied as it is.

The radiation image information reading apparatus 20 having the illustrated configuration
The effect of 0 is as described above except that the stimulated emission light M ′ emitted from the back surface of the sheet 50 (the surface opposite to the incident surface of the excitation light L) by the irradiation of the excitation light L is received. Since the radiation image information reading apparatus 100 is the same as the radiation image information reading apparatus 100, the description is omitted here.

Even if the condensing optical system of the present invention is applied to the radiation image information reading apparatus 200 having such a configuration as the converging means for stimulating emitted light, the aperture of each condensing lens constituting the condensing optical system can be used. Since the efficiency is high, the light collection efficiency can be increased and the size of the device can be reduced. Therefore, it is possible to obtain a high-quality radiation image even with a compact device.

In each of the above-described two embodiments, an example is described in which the condensing optical system according to the present invention is applied to a radiation image information reading apparatus using a stimulable phosphor sheet. The system is not limited to a radiation image information reading device, but any system that requires a condensing optical system for condensing emitted light or transmitted light from an object irradiated in an irradiation range that is shorter than its length , Can also be applied to devices.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a conventional technique;

FIG. 2 is a schematic view showing a condensing optical system of the present invention.

FIG. 3 is a schematic diagram showing a radiation image information reading apparatus 100 to which the light condensing optical system of the present invention is applied.

4 is a cross-sectional view showing a cross section taken along line II of the radiation image information reading apparatus 100 shown in FIG. 3;

FIG. 5 is a diagram showing details of a line sensor and a condensing optical system in the radiation image information reading apparatus 100 shown in FIGS. 3 and 4;

FIG. 6 is a cross-sectional view showing another radiation image information reading apparatus 200 to which the condensing optical system of the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Broad area laser (BLD) 12 Optical system consisting of a collimator lens and a toric lens 16 Condensing optical system 17 Excitation light cut filter 20 Line sensor 21 Photoelectric conversion element 30 Image information reading means 40, 40 'Scanning belt 50 Storage phosphor Sheet L Excitation light M, M 'Stimulated emission light A, B, E Condensing area a, b, e Condensing lens

Claims (2)

[Claims] 1. An apparatus for condensing emitted light or transmitted light from an object irradiated in an irradiation area having a width shorter than a length,
A condensing optical system provided with a plurality of rows of condensing lenses in a length direction and a width direction of the irradiated area, respectively, wherein each of the condensing lenses has an outer diameter (d) in the length direction. The length (r) of the light emission or transmission region of the light condensed by the one condensing lens on the irradiated surface of the object in the length direction is n times or less,
n is an integer greater than 1, and is equal to the number of rows of the condenser lens in the width direction. 2. The object according to claim 1, wherein the object is a stimulable phosphor sheet on which radiation image information is accumulated, and the illuminated light is irradiated by the excitation light that is linearly applied to the stimulable phosphor sheet. 2. The light-collecting optical system according to claim 1, wherein the stimulable phosphor sheet emits stimulating light emitted from a rear surface side portion of the stimulable phosphor sheet corresponding to the irradiated portion.