JPH04244925A - Radiation thermometer - Google Patents

Abstract

PURPOSE:To obtain a radiation thermometer for achieving measurement with an improved S/N ratio without interrupting a measurement light flux wastefully and preventing thermal radiation from a member from being mixed with a measurement light. CONSTITUTION:An incidence light entering through an area near the optical axis 1 out of incidence light entering from a front is transmitted through a finder lens 3 which is provided at the center of a sub-mirror 3 and is led to a finder optical system 7 which is located at a rear portion of a main mirror 2 through a transmission portion 5a of a mirror 5 and a transmission portion 2a of the main mirror 2, enters away from the optical axis 1, and the incidence light is reflected by the main mirror 2 and the sub-mirror 3 and further is reflected by a mirror 51 and is led to a light-receiving element 4.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has a Cassegrain optical system that reflects incident light from the front on a primary mirror, further reflects the reflected light on a secondary mirror, and then guides it to a light receiving element. The present invention relates to a radiation thermometer having a finder for confirming a measurement position on a measuring object.

0002

[Prior Art] When a lens system is used as an optical system in a radiation thermometer that measures light in a wide wavelength range within the infrared region or light in a wide wavelength range from the infrared region to the visible light region, A lens material that transmits light in the wide wavelength range is required, and the material is expensive and the chromatic aberration of the lens system is a problem. BACKGROUND ART Optical systems have been widely used in the past, and various improvements have been made to radiation thermometers using Cassegrain optical systems.

FIG. 3 is a diagram showing an example of a conventional radiation thermometer using a Cassegrain optical system (Japanese Patent Publication No. 1983-1999).
(See Publication No. 53485). The conventional technology will be explained below with reference to this figure.

The incident light that enters from the front (left side in FIG. 2) is reflected by the primary mirror 2, except for the incident light near the optical axis 1, and then reflected by the secondary mirror 3 and then reflected at the center of the primary mirror 2. hole 2 provided
The light enters the light receiving element 4 through the light receiving element 4, and the energy of the incident light is measured by the light receiving element 4, and this measured energy is converted into the temperature of the object to be measured that has radiated the incident light.

[0005] Also, a finder lens 2a constituting a part of the finder optical system is formed in the center of the secondary mirror 3, and the incident light passing near the optical axis 1 passes through this finder lens 3a. The light is reflected by the mirror 5 in a substantially perpendicular direction, and then passes through the pentaprism 6 or other finder optical system 7 to be used for human eye observation of the object to be measured.

FIG. 4 is a perspective view showing a mounting member for mounting the mirror 5 shown in FIG. 2, which is disclosed in the above-mentioned Japanese Patent Publication No. 63-53485. The mirror 5 is fixed by adhesion or the like to a mounting member 11, and this mounting member 11 is fixed to a body (not shown) of the radiation thermometer using a screw hole 11b. The mirror 5 is fixed obliquely as shown in the figure, and the light reflected by the mirror 5 is guided to a finder optical system such as a pentaprism 6 (see FIG. 2). On the other hand, light passing around the mirror 5 is guided to the light receiving element 4 through an opening 11a provided in the mounting member 11.

[0007]

With the above structure, the mirror 5 is placed between the secondary mirror 3 and the primary mirror 2 in a position that was conventionally considered a dead space. Compared to the previously known Cassegrain optical system for radiation thermometers, in which a mirror 5' that guides the incident light to the finder optical system was placed in front of the secondary mirror 3, this optical system for radiation thermometers as a whole was It has the advantage that it can be configured to be short in the front-rear direction, but on the other hand, the light that reaches the light receiving element 4 is only the light that has passed through the aperture 11a,
There is a limit to how wide the aperture 11a can be, and therefore the amount of light received by the light receiving element 4 decreases, resulting in a problem of poor S/N ratio. Further, the infrared light thermally radiated from the mounting member 11 will be incident on the light receiving element 4, which also causes a problem that the S/N ratio will decrease. SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a radiation thermometer that can perform measurements with a better S/N ratio than the conventional example.

[0008]

[Means for Solving the Problems] A radiation thermometer of the present invention for achieving the above object includes a primary mirror that reflects incident light incident from the front and has a transmitting portion in the center that transmits light;
a secondary mirror with a finder lens forming part of a finder optical system in the center that reflects the light reflected by the primary mirror; and a secondary mirror that reflects the reflected light from the secondary mirror toward the light receiving element. a mirror having a transmitting portion in the center that transmits the transmitted light so that the transmitted light transmitted through the finder lens is guided to a finder optical system other than the finder lens disposed at the rear; It is characterized by this.

[0009] Here, the transmitting part of the primary mirror and the transmitting part of the mirror may have some kind of transmitting material such as transparent glass that transmits the necessary light, or there may be a transparent material therein. It may simply have holes. or,
The mirror may be arranged behind the secondary mirror and in front of the primary mirror, or may be arranged behind the primary mirror.

0010

[Function] The radiation thermometer of the present invention has the ability to
The light is transmitted through the finder lens and guided as it is to the finder optical system disposed behind the primary mirror via the transmitting part of the mirror and the transmitting part of the primary mirror, and the measurement light is reflected by the mirror. Therefore, compared to the conventional example described above, there is no member on the light fall that obstructs the measurement light beam, such as the mounting member 11 (see FIG. 4) in the conventional example.
Therefore, the amount of received light can be increased. Also,
As in the case of the conventional example above, a mirror mounting member is necessary, but the mirror is placed on the light-receiving element side of this mounting member, so the radiant heat from this mounting member is blocked by the mirror. Radiant heat is also less likely to be guided to the light receiving element.

[0011]

[Examples] Examples of the present invention will be described below. FIG. 1 is a diagram showing a schematic configuration of an embodiment of a radiation thermometer of the present invention. Components corresponding to those shown in FIG. 3 are designated by the same reference numerals as those used in FIG. 3, and explanations thereof will be omitted.

Of the light incident from the front (left side in FIG. 1), light incident away from the optical axis 1 is reflected by the primary mirror 2,
It is reflected by the secondary mirror 3 and further reflected by the mirror 51 as shown in FIG.
The light is guided upward to the light receiving element 4, whereby the temperature of the object to be measured is measured.

On the other hand, among the incident light, the light that enters near the optical axis 1 passes through the finder lens 3a provided at the center of the secondary mirror 3, and passes through the hole 51a provided at the center of the mirror 51. In addition, a hole 2 provided in the center of the primary mirror 2
After passing through point a, the object is guided to a finder optical system 7, whereby the object to be measured is observed by placing the eye in the direction in which the optical axis 1 is extended, as shown in FIG.

[0014] Here, the mirror 51 has a hole 51a in the center.
However, when manufacturing the mirror 51, it is recommended not to vapor-deposit aluminum, silver, etc. in the center of the glass plate, or to vapor-deposit it on one surface and then apply it only to the center. It may also be configured by partially removing the vapor deposition.

The mirror 51 manufactured in this manner is attached to a mounting member 52 schematically shown in FIG.
2 is fixed to the body (not shown) of this radiation thermometer. Note that focus adjustment is performed by moving the primary mirror 2 and the secondary mirror 3 integrally in the front-back direction. Furthermore, since various finder optical systems 7 are widely known, detailed illustrations and explanations thereof will be omitted here. In this way, in the above embodiment, there is no member that simply wastefully blocks part of the measurement light flux, and therefore the amount of received light can be increased accordingly, and the S/N ratio of the received light signal is improved. Furthermore, since a mirror 51 is attached to the surface of the mounting member 52 on the light receiving element 4 side, this mirror 51 prevents infrared rays caused by heat radiation from the mounting member 52 from entering the light receiving element. The S/N ratio is improved. Furthermore, the above embodiment has a simpler structure as a whole than the conventional one, so it is possible to reduce costs, reduce the size, and improve the degree of freedom in design. The structure is particularly suitable for portable radiation thermometers.

FIG. 2 is a schematic diagram of another embodiment of the radiation thermometer of the present invention. Components corresponding to those shown in FIG. 1 are given the same reference numerals as those used in FIG. 1, and explanations thereof will be omitted. In this embodiment, a mirror 53 corresponding to the mirror 51 shown in FIG. 1 is arranged behind the primary mirror 2. In this embodiment as well, the S/N ratio is improved as in the embodiment shown in FIG. In addition, by adopting the configuration shown in Figure 2, the design of accessories becomes easier due to the cylindrical shape and simplification.
This improves the degree of freedom in mounting direction at temperature measurement sites, making it suitable for use as a stationary radiation thermometer.

In the conventional example (see FIG. 3), diffuse reflection occurs at the edge of the mirror 5, which may become a noise source, but in each of the above embodiments, the mirrors 51, 53
It is easily possible to form a mirror by attaching a thin film that transmits visible light to the center of the mirror and attaching silver or the like to the periphery of the mirror, and by configuring it in this way, the above-mentioned diffused reflection can be prevented.

[0018]

Effects of the Invention As explained above in detail, the radiation thermometer of the present invention includes a mirror having a transmitting part in the center, guides the light reflected by the mirror to the light receiving element, and transmits the light through the central transmitting part. Since the light is guided to the finder optical system, it is possible to perform measurements with a good S/N ratio.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a radiation thermometer of the present invention.

FIG. 2 is a schematic configuration diagram of another embodiment of the radiation thermometer of the present invention.

FIG. 3 is a diagram showing an example of a conventional radiation thermometer using a Cassegrain optical system.

4 is a perspective view of a mirror mounting member of the conventional radiation thermometer shown in FIG. 3; FIG.

[Explanation of symbols]

1 Optical axis 2 Primary mirror 2a Hole (transparent part) 3 Secondary mirror 3a Finder lens 4 Photo receiving element 5 Mirror 5’ mirror 6 Pentaprism 7 Finder optical system 11 Mounting parts 11a Opening 51 Mirror 51a Transparent part 52 Mounting parts 53 Mirror

Claims (3)

[Claims] Claim 1: A primary mirror that reflects incident light incident from the front and has a transmitting section in the center that transmits the light, and a finder optical system in the center that reflects the reflected light reflected by the primary mirror. A secondary mirror including a finder lens forming a part of the secondary mirror is arranged behind the primary mirror, and the transmitted light that has passed through the finder lens is reflected toward the light receiving element side by the secondary mirror. 1. A radiation thermometer comprising: a mirror having a transmitting portion in the center that transmits the transmitted light so as to be guided to a finder optical system other than the finder lens. 2. The radiation thermometer according to claim 1, wherein the mirror is arranged behind the secondary mirror and in front of the primary mirror. 3. The radiation thermometer according to claim 1, wherein the mirror is placed behind the primary mirror.