JPH1012185A - Photomultiplier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photomultiplier with enhanced light-receiving efficiency. SOLUTION: In a photomultiplier, a flange F is formed at one end of a metal side tube 3, and melt-bonded with a light receiving surface plate 1. A circular stem 4 constituting a base table part is formed at the other end of the metal side tube 3. A focusing electrode 6, an electron multiplier part 5, and an anode 10 are arranged from the light receiving surface plate 1 side on the inside of a vacuum container formed by these component. A photoelectric surface 2 is formed on the inner surface of the light receiving surface plate 1, and a projection 31 having practically the same shape as a space partitioned b the inner circumferential edge of the flange F is integrally formed on the outer surface of the light receiving surface plate 1. A semi-globular lens 30 practically equal to the diameter of the metal side tube 3 is closely connected to the projection 31 in the lower surface. In this constitution, light to be detected is deflected without attenuation, photo-intercepting efficiency on the photoelectric surface is enhanced. As a result, the sensibility of the photomultiplier is enhanced compared with the conventional one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a photomultiplier tube.

[0002]

2. Description of the Related Art As an optical sensor for measuring weak light or the like,
A so-called head-on type photomultiplier has been widely used. The head-on type photomultiplier tube has one end of a cylindrical vacuum vessel as a light receiving face plate. The vacuum vessel of such a head-on type photomultiplier is generally made of a glass tube. In recent years, as disclosed in JP-A-6-310084, a cylindrical metal side tube is used. When,
A structure having one end thereof and a light receiving surface plate joined to the inner surface of the inward flange has been developed.

[0003]

However, in a vacuum vessel made of a metal side tube, the area of the light receiving surface is reduced by the inward flange of the metal side tube as compared with a glass tube having the same tube diameter. Therefore, the light receiving efficiency of the light to be detected, which is a detection target, is deteriorated.

Accordingly, an object of the present invention is to provide a photomultiplier tube in which the vacuum vessel is a metal side tube, which does not deteriorate the light receiving efficiency.

[0005]

According to the photomultiplier tube according to the present invention, a vacuum vessel in which a light receiving surface plate having a photoelectric surface is joined to the inner surface of a flange formed at one end of a cylindrical metal side tube. And a plano-convex lens that is joined to the end of the vacuum vessel on the side of the light-receiving surface plate and deflects incident light toward the center of the light-receiving surface plate. Is characterized in that a convex portion having substantially the same shape as the space defined by the above is integrally formed. In the configuration of the present invention, since the plano-convex lens is joined to the end of the vacuum vessel on the light receiving surface plate side, the light to be detected incident on the light receiving surface plate is deflected toward the center of the light receiving surface plate. Further, by providing the convex portion on the outer surface of the light receiving surface plate, the plano-convex lens and the vacuum container are joined without any gap, and light is not substantially attenuated due to multiple reflection at the joining surface. Therefore, the photocathode efficiently receives the detected light.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a photomultiplier according to the present invention will be described with reference to the drawings. Further, the terms “upper” and “lower” used in this specification are used in correspondence with the drawings.

FIGS. 1 and 2 are a side sectional view and a top view, respectively, showing an embodiment of a photomultiplier tube according to the present invention. The illustrated photomultiplier is a so-called head-on type and has a cylindrical vacuum vessel.

The vacuum vessel is a light receiving surface plate 1 made of, for example, UV glass airtightly bonded to a cylindrical metal side tube 3 and an inner surface of an inward flange F formed at one end of the metal side tube 3.
And a circular stem 4 provided at the other end of the metal side tube 3 and constituting a base portion. A photoelectric surface 2 is formed on the inner surface of the light receiving surface plate 1.

A dynode 7 for forming an electron multiplier 5 by stacking a plurality of stages of a focusing electrode 6 and a flat plate having two-dimensionally arranged electron multipliers 8 from the side of the photocathode 2 inside the vacuum vessel. , 9 and the anode 10 are sequentially arranged. A connection terminal 20 protrudes from the outer peripheral portions of the dynodes 7 and 9 and the anode 10, and is connected to one end of the stem pin 11. The other end extends through the stem 4 to the outside.

In the photomultiplier according to the present embodiment, a plano-convex lens, preferably a hemispherical lens 30, is further joined to the upper end surface of the vacuum vessel. The diameter of the lower surface of the hemispherical lens 30 is substantially equal to the diameter of the upper surface of the vacuum container. The lower surface is specially flattened.
By the way, the hemispherical lens 30 is for expanding the effective light receiving area of the light receiving face plate 1 as described later.
For that purpose, it is preferable to arrange the hemispherical lens 30 coaxially with the vacuum container. However, even when the hemispherical lens 30 is arranged as described above, when the outer surface of the light receiving surface plate 1 and the lower surface of the hemispherical lens 30 are flat, the detected light is subjected to multiple reflections due to a gap formed therebetween. And the effect is offset. Therefore, in the present embodiment, the gap between the light receiving surface plate 1 and the light receiving surface plate 1 is eliminated by integrally forming the columnar convex portion 31 on the outer surface.

More specifically, the outer diameter of the projection 31 is substantially equal to the inner diameter of the flange F of the metal side tube 3. In order to form the convex portion 31, when the light receiving face plate 1 is joined to the flange F of the metal side tube 3, heat fusion as shown in FIG. 3 is performed. First, an electric furnace (not shown) provided with a carbon base S having a cylindrical concave portion 32 having a diameter smaller than the diameter of the metal side tube 3 and larger than the inner diameter of the flange F is prepared. Next, the light receiving face plate 1 is placed on the inner surface of the metal tube 3 with the flange F facing downward. In this state, the concave portion 33 formed by the flange F and the light receiving face plate 1 is opposed to the concave portion 32 of the base S.
The metal side tube 3 is disposed on the table S (see FIG. 3A). After that, the light receiving face plate 1 and the metal side tube 3 are
Is heated at 850 ° C. for one hour, the light-receiving face plate 1 melts down to the surface position of the flange F, so that the protrusions 31
Are integrally formed (see FIG. 3B). At this time,
Even if the convex portion 31 is formed with a height exceeding the surface position of the flange F, it does not come into contact with the table S, so that the table S
It is not contaminated by carbon.

When the hemispherical lens 30 is joined to the light receiving face plate 1 having the projections 31 formed in this manner as described above, the two are brought into close contact with each other. In order to make the hemispherical lens 30 be in close contact with the flange F and the outer surface of the light receiving face plate 1, it is preferable that the height of the convex portion 31 is substantially the same as the thickness of the flange F. .

In actual manufacturing, the height of the convex portion 31 slightly varies based on the surface position of the flange F. In order to fill the gap between the two due to this variation, it is preferable to bond them with an optical adhesive such as optical cement or silicone rubber having the same refractive index as the hemispherical lens 30. In this case, since the optical adhesive is interposed between the light receiving face plate 1 and the hemispherical lens 30, the optical efficiency is improved.

The lower surface of the hemispherical lens 30 and the projection 3
It is more preferable that the end face of 1 is polished flat.
This prevents light diffusion such as reflection and scattering of the light to be detected at the joining surface between the hemispherical lens 30 and the light receiving face plate 1.

In the photomultiplier tube configured as described above,
When the light to be detected enters as shown by the arrow in FIG.
Even if it is directly above the flange F, it is deflected by the hemispherical lens 30 and heads toward the center of the light receiving face plate 1. For this reason, the effective light receiving area of the light receiving face plate 1 increases. Further, in this photomultiplier tube, since there is no gap between the hemispherical lens 30 and the light receiving surface plate 1, light to be detected having high light receiving efficiency is received by the photoelectric surface 2 without being attenuated by multiple reflection. When such a light to be detected is received by the photocathode 2, more photoelectrons are emitted into the vacuum due to the photoelectric effect than in the past. After the photoelectrons are secondary-multiplied using the electron multiplier 5, the resulting secondary electrons are also collected in the anode 10 in a larger amount than in the prior art.
The electric signal output from the outside is also large. Therefore,
In the photomultiplier according to the present embodiment, higher sensitivity can be obtained as compared with the related art.

[0016]

According to the photomultiplier tube of the present invention, since the hemispherical lens representing the plano-convex lens is joined to the light receiving face plate side of the vacuum vessel, the light to be detected entering the light receiving face plate is centered. Since the light is deflected closer, the light receiving efficiency of the photocathode increases. In addition, since the convex portion is formed on the outer surface of the light receiving surface plate, no gap is generated at the joint surface with the hemispherical lens.
For this reason, the detected light is not reflected or scattered by the bonding surface, and the detected light received by the photocathode is not attenuated. Therefore, this photomultiplier tube has higher sensitivity than before.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing one embodiment of a photomultiplier tube according to the present invention.

FIG. 2 is a cross-sectional view taken along line AA of the photomultiplier tube shown in FIG.

FIG. 3 is a sectional view sequentially showing a process of forming a convex portion on a light receiving surface plate of the photomultiplier according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light receiving surface plate, 2 ... Photoelectric surface, 3 ... Metal side tube, F ... Flange, 4 ... Stem, 5 ... Electron multiplication part, 6 ... Focusing electrode, 7,
9 ... dynode, 10 ... anode, 11 ... stem pin,
12 ... hermetic glass, 20 ... connection terminal, 30 ... hemispherical lens, 31 ... convex part, 32, 33 ... concave part, S ... stand.

Claims (1)

[Claims] 1. A vacuum vessel in which a light receiving face plate having a photoelectric surface is joined to an inner surface of a flange formed at one end of a cylindrical metal side tube; A plano-convex lens for deflecting light toward the center of the light-receiving surface plate, wherein the outer surface of the light-receiving surface plate has substantially the same shape as the space defined by the inner peripheral edge of the flange. A photomultiplier tube, wherein a convex portion is integrally formed.