Radiation thermometer

Abstract

To provide a radiation thermometer capable of easily and accurately aligning a measurement range with a measurement target while achieving downsizing and improving the utilization efficiency of infrared radiation.SOLUTION: A laser reflection mirror 8 or a mirror central window 26a provided in an infrared reflection mirror 26 is positioned such that a light beam of an aiming laser light, once converged by a convex conical lens 6, becomes near the minimum diameter at the position of reflection of the laser reflection mirror 8 or transmission of the mirror central window 26a. The beam of the aiming laser light is diffusely reflected in a ring shape on the surface of a measurement target 10 so as to indicate the measurement range RM of infrared radiation emitted from the measurement target 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radiation thermometer that measures the temperature of an object in a non-contact manner based on infrared energy radiated from the object. [Background technology]

[0002] Conventionally, there have been radiation thermometers that measure the temperature of an object without contact by detecting infrared energy emitted from the object, and it is known that a laser beam is used as a sight during the measurement (see, for example, Patent Documents 1 and 2). A radiation thermometer measures temperature using infrared rays that cannot be seen with the naked eye, and indicates the infrared measurement range on the surface of the object by using a laser beam, which is visible light, as a sight.

[0003] Patent Document 1 describes a method for combining an infrared optical axis and a laser optical axis to aim a circular (ring-shaped) laser beam generated by a conical lens (axicon lens) that transmits laser beams, and forms this circular laser beam outside the infrared measurement range (detection area). Convex as well as concave axicon lenses are also described. Patent Document 2 describes a method for combining an infrared optical axis and a laser optical axis to aim a single point-like laser beam that passes through the center of the infrared lens. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-177560 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-226864 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, the beam of laser light is expanded by the axicon lens to form a large laser beam, which is then reflected by the laser reflecting mirror, and the laser reflecting mirror must be large to reflect this large laser beam, and the infrared lens must also be large in the radial direction because the laser light must be transmitted through the outer diameter portion of the infrared lens, resulting in an increase in the size of the radiation thermometer. Furthermore, as the laser reflecting mirror and infrared lens become larger, the infrared utilization range through which infrared rays emitted from the object to be measured pass becomes narrower, which poses the problem of reduced infrared utilization efficiency.

[0006] Furthermore, in Patent Document 2, the laser light is a single point, so it only indicates the center point of the measurement range of the radiation thermometer, and is unable to indicate the infrared measurement range, which changes depending on the measurement distance between the radiation thermometer and the object being measured. This poses a problem in that it is difficult to accurately adjust the infrared measurement range of the object being measured according to the measurement distance.

[0007] The present invention aims to solve the above problems and provide a radiation thermometer that can easily and accurately adjust the infrared measurement range on the object to be measured, and that can improve the efficiency of infrared utilization while realizing a compact radiation thermometer. [Means for solving the problem]

[0008] In order to achieve the above object, a radiation thermometer according to the present invention measures the temperature of a measurement object by detecting infrared energy radiated from the measurement object with an infrared sensor, an optical system including an infrared lens that focuses the infrared energy and guides it to the infrared sensor, a convex cone-shaped lens that first focuses the beam of the aiming laser light emitted from the laser irradiation unit and then diffuses it into a ring shape, and a laser reflection mirror and / or an infrared reflection mirror that combines the infrared optical axis and the laser optical axis coaxially toward the measurement object, At a position in the optical system where the aiming laser light is reflected by the laser reflecting mirror, or at a position where the aiming laser light passes through a mirror center window provided in the infrared reflecting mirror, the laser reflecting mirror or the mirror center window is positioned so that the beam of light once narrowed by the convex conical lens has a diameter close to its minimum, and the beam of light of the aiming laser light is diffused in a ring shape on the surface of the object to be measured so as to indicate the measurement range of infrared rays emitted from the object to be measured.

[0009] According to this configuration, the central mirror window of the laser reflecting mirror or infrared reflecting mirror is positioned at a position where the beam of the aiming laser light, which has been once narrowed by the convex cone-shaped lens, is near its smallest diameter, and is diffused in a ring shape on the surface of the object to be measured.This ring-shaped aiming laser light makes it easy to accurately adjust the measurement range of the object to be measured, which changes depending on the measurement distance, and since the laser reflecting mirror or central mirror window can be made smaller, the radiation thermometer can be made smaller and the infrared utilization range can be expanded, making it possible to improve the infrared utilization efficiency.

[0010] In the present invention, it is preferable that a first laser reflecting mirror is disposed near the minimum diameter of the beam of the aiming laser beam once focused by the convex cone-shaped lens, and the beam of light from this first laser reflecting mirror is reflected by a second laser reflecting mirror disposed on the combined coaxial line and irradiated in the combined coaxial line direction, then passes through a lens center window provided in the infrared lens and is diffused in a ring shape on the surface of the object to be measured. In this case, the measurement range on the object to be measured can be easily adjusted accurately and the first and second laser reflecting mirrors can be made smaller, thereby making it possible to make the radiation thermometer smaller and to improve the utilization efficiency of infrared rays by expanding the utilization range of infrared rays.

[0011] In the present invention, it is also preferable that the infrared energy is guided to the infrared sensor by the infrared reflecting mirror, and a mirror center window of the infrared reflecting mirror is located near the minimum diameter of the beam of the aiming laser beam once focused by the convex cone-shaped lens, so that the combined aiming laser beam irradiated in the coaxial direction passes through the mirror center window of the infrared reflecting mirror and the lens center window of the infrared lens and is diffused in a ring shape on the surface of the measurement object. In this case, it is possible to easily accurately adjust the measurement range on the measurement object and to reduce the size of the mirror center window of the infrared reflecting mirror, thereby enabling the size of the radiation thermometer and the utilization efficiency of infrared rays to be improved by expanding the utilization range of infrared rays.

[0012] Preferably, the first and second laser reflecting mirrors each have an irradiation direction adjusting mechanism for adjusting the irradiation direction of the aiming laser beam, so that the irradiation direction of the aiming laser beam can be easily adjusted to align the infrared optical axis and the laser optical axis with a combined coaxial axis, and the aiming laser beam can be accurately aligned with the second reflecting mirror and the center of the lens central window.

[0013] Preferably, the convex conical lens is a convex circular conical lens or a convex polygonal conical lens, so that the beam of the aiming laser light can be easily diffused into a ring shape. [Effects of the Invention]

[0014] In the present invention, the central mirror window of the laser reflecting mirror or infrared reflecting mirror is positioned at a position where the beam of the aiming laser light, which has been once narrowed by the convex cone-shaped lens, is near its smallest diameter, and is diffused in a ring shape on the surface of the object to be measured.This ring-shaped aiming laser light makes it easy to accurately adjust the measurement range of the object to be measured, which changes depending on the measurement distance, and since the laser reflecting mirror or central mirror window can be made smaller, the radiation thermometer can be made smaller and the infrared utilization range can be expanded, making it possible to improve the efficiency of infrared utilization. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing a radiation thermometer according to a first embodiment of the present invention. [Figure 2] 1A and 1B are perspective views showing an example of an infrared lens. [Figure 3] FIG. 2 is a schematic diagram illustrating the operation of the radiation thermometer of FIG. [Figure 4] This is a characteristic diagram comparing the infrared measurement range and the ring laser diameter. [Figure 5] FIG. 10 is a perspective view showing the attached state of the second laser reflecting mirror. [Figure 6] 1A and 1B are side views showing an example of an Axico lens. [Figure 7] FIG. 10 is a cross-sectional view showing a main part of a radiation thermometer according to a second embodiment. [Figure 8] FIG. 1 is a perspective view showing a convex polygonal pyramidal lens. [Figure 9] FIG. 10 is a diagram showing a ring laser with multiple points irradiated onto an object to be measured. [Figure 10] FIG. 10 is a cross-sectional view showing a radiation thermometer of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments of the present invention will now be described with reference to the drawings. Fig. 1 shows a cross-sectional view of a radiation thermometer 1 according to a first embodiment of the present invention. This radiation thermometer 1 detects infrared energy radiated from a measurement object 10 to measure the temperature of the measurement object 10.

[0017] The radiation thermometer 1 is equipped with a control unit 20 that is built into the main body and controls the entire device, and although not shown, this control unit 20 controls a well-known detection circuit that detects infrared light reception signals, a temperature calculation circuit that converts this light reception signal into a voltage signal to calculate the temperature of the object to be measured, a display circuit that displays the calculated temperature, etc. The control unit 20 may not be built-in but may be externally connected.

[0018] 1, the radiation thermometer 1 includes an infrared sensor 3 that detects infrared energy emitted from a measurement object 10, and a laser irradiation unit 4 that irradiates the surface of the measurement object 10 with a laser beam for aiming. The infrared sensor 3 may be a thermopile, and the laser irradiation unit 4 may be a semiconductor laser (laser diode).

[0019] The optical system includes an infrared lens 2 that collects infrared energy from a measurement object 10 and guides it to an infrared sensor (thermopile) 3, a convex conical lens 6 that first focuses the beam of the aiming laser light emitted from a laser irradiation unit 4 and then diffuses it into a ring shape, and laser reflecting mirrors 8 and 9 that combine the infrared light axis and the laser light axis into a coaxial line RLX toward the measurement object 10. The aiming laser light is collimated by a collimator lens 5 and becomes a ring laser light RL by the convex conical lens 6, which then passes through a central lens window 2a of the infrared lens 2 and is irradiated onto the measurement object 10. As shown in FIG. 6(A), the convex conical lens 6 is, for example, a convex conical lens (convex axicon lens).

[0020] In this example, the laser reflecting mirror has first and second laser reflecting mirrors 8 and 9. The first laser reflecting mirror 8 is held by a first mirror holding portion (first mirror stay) 7, and the second laser reflecting mirror 9 is held by a second mirror holding portion (second mirror stay) 11.

[0021] A first laser reflecting mirror 8 is placed near the minimum diameter of the beam of the aiming laser light that has been once focused by the convex axicon lens (conical lens) 6, and a second laser reflecting mirror 9 is placed on the combined coaxial line RLX. The laser beam reflected from the first laser reflecting mirror 8 is reflected by the second laser reflecting mirror 9 and irradiated in the direction of the combined coaxial line RLX, then passes through a lens center window 2a provided in the infrared lens 2 and is diffused in a ring shape on the surface of the measurement object 10 so as to indicate the infrared measurement range RM.

[0022] As shown in Figure 1, the laser beam reflected by the second laser reflecting mirror is contained within the infrared utilization range RU, and gradually expands into a ring shape, approaching the inner edge of the infrared utilization range RU, while being irradiated onto the surface of the measurement object 10 and indicating the infrared measurement range RM. At this time, when the distance between the radiation thermometer 1 and the measurement object 10 exceeds a certain measurement distance, the expanding ring laser RL comes into contact with the inner edge of the infrared utilization range RU and coincides with the infrared measurement range RM (Figure 4), making it possible to accurately match the infrared measurement range RM of the measurement object 10, which changes depending on the measurement distance.

[0023] In this case, the first laser reflecting mirror 8, which is arranged near the minimum diameter of the beam of the aiming laser light, can be made smaller because the laser beam is small, and the second laser reflecting mirror 9, which is arranged to reflect the laser beam near this minimum diameter, can also be made smaller. Accordingly, the first and second mirror holding units 7 and 11, which hold the first and second laser reflecting mirrors 8 and 9, respectively, can also be made smaller. Furthermore, by making these mirrors smaller, the infrared utilization range RU can be expanded, and the infrared utilization efficiency can be improved.

[0024] Figures 2(A) and (B) show an infrared lens 2. The infrared lens 2 is made of a lens material such as silicon (Si) or germanium (Ge) that transmits infrared light but not visible laser light. As shown in Figure 2(A), a central lens window 2a made of a parallel plate of optical glass is formed in the center of the infrared lens 2 and is bonded to the lens material. The central lens window 2a transmits visible laser light but not infrared light. As shown in Figure 2(B), the infrared lens 2 may be configured with a hole 2b simply drilled in the center of the lens material instead of the central lens window 2a.

[0025] As shown in Fig. 3, the radiation thermometer 1 irradiates the surface of the measurement object 10 with a ring laser RL. Although radiation thermometers use infrared rays, these infrared rays are not visible to the naked eye, so it is difficult to accurately grasp the infrared measurement range without a laser sight. As in this embodiment, by indicating the infrared measurement range RM with an enlarged ring-shaped ring laser RL instead of the conventional single center point, the measurer can easily accurately align the infrared measurement range RM on the measurement object 10.

[0026] Figure 4 compares the infrared measurement range (measurement field of view range) RM of the measurement object 10 with the diameter of the ring laser. This measurement field of view range indicates the inner edge of the circle of the infrared utilization range RU. At close distances, the infrared measurement range RM and the diameter of the ring laser do not match, but at commonly used measurement distances, such as about 250 mm, they roughly match, and at distances of about 500 mm or more, they match completely. In this way, this ring laser RL can accurately indicate the infrared measurement range RM of the measurement object 10, which changes depending on the measurement distance.

[0027] 5, the second laser reflecting mirror 9 is held by the lens barrel 12 via the second mirror holding part 11. The second laser reflecting mirror 9 and the second mirror holding part 11 block infrared rays and reduce the amount of infrared light received, so in the first embodiment, these are made smaller to improve the amount of infrared light received. <Examples and Comparative Examples>

[0028] The example shown in Figure 1 and the comparative example shown in Figure 10 are described in detail below. Figure 1 shows the case where the convex axicon lens 6 of the present invention is used, and Figure 10 shows the case where the concave axicon lens 16 is used as a comparative example (see, for example, Patent Document 1). Both axicon lenses generate a ring laser, but as shown in the cross-sectional views of axicon lenses shown in Figures 6(A) and (B), there are convex axicon lenses using a convex conical surface (A) and concave axicon lenses using a concave conical surface (B). The laser beam shrinks once after passing through the convex axicon lens 6 (A), while the laser beam expands uniformly after passing through the concave axicon lens 16 (B). <Example>

[0029] In Figure 1, the laser beam incident on the convex axicon lens 6 is a parallel beam with a diameter of approximately 2 mm. The material of the convex axicon lens 6 is, for example, polycarbonate, with a refractive index of 1.58 and a conical surface apex angle of 174°. The beam is smallest at a measurement distance of approximately 16 mm from the convex axicon lens 6, with a diameter of approximately 1 mm. The first laser reflecting mirror 8 is positioned near the position where the laser beam is smallest, and the second laser reflecting mirror 9 that reflects this laser beam and the infrared lens 2 are also positioned near the smallest positions. That is, the second laser reflecting mirror 9 is positioned at a measurement distance of approximately 19 mm from the convex axicon lens 6, and the diameter of the laser beam at this position is small, approximately 1.2 mm. The infrared lens 2 is positioned at a measurement distance of approximately 23 mm from the convex axicon lens 6, and the diameter of the laser beam at this position is small, approximately 1.4 mm.

[0030] By arranging the first laser reflecting mirror 8, the second laser reflecting mirror 9, and the infrared lens 2 near the position where the laser beam is smallest, the size of the first and second laser reflecting mirrors 8, 9, and the first and second mirror holding parts 7, 11 that hold them, as well as the size of the lens center window 2a of the infrared lens 2 can be made as small as possible.

[0031] The size of the second laser reflecting mirror 9 is approximately 3 mm square, and the size of the lens central window 2a is approximately 3 mm in diameter. The second laser reflecting mirror 9 and lens central window 2a are arranged on the combined coaxial line RLX, and the infrared rays necessary for radiation temperature measurement do not pass through them, resulting in a decrease in the amount of infrared light received. However, by making the size of the second mirror 9 and lens central window 2a as small as possible, it is possible to minimize the decrease in the amount of infrared light received. <Comparative Example>

[0032] In contrast, in the comparative example of Figure 10, the laser beam expands after passing through the concave axicon lens 16, so the laser beam becomes large at the position of the first laser reflecting mirror 18, and also at the positions of the second laser reflecting mirror 19 and the lens central window 15a. Therefore, the first and second laser reflecting mirrors 18, 19, the first and second mirror holders 17, 22 that hold them, and the lens central window 15a of the infrared lens 2 are large. The diameters of the laser beam at the positions of the second laser reflecting mirror 19 and the lens central window 15a are approximately 3.2 mm and 3.4 mm, respectively. Furthermore, the second laser reflecting mirror 19 needs to be large to accommodate the 45° oblique incidence, so the size of the second laser reflecting mirror 19 needs to be approximately 6 mm square, and the size of the lens central window 15a also needs to be approximately 6 mm in diameter. Due to these shielding factors, the usable range RU of the infrared light becomes very narrow. <Comparative evaluation>

[0033] In the embodiment in Fig. 1, the use of the convex axicon lens 6 causes the laser beam to first shrink, and then, when this laser beam has become smaller, it passes through the laser reflecting mirrors 8 and 9 and the infrared lens 2, so the laser reflecting mirrors 8 and 9 and the central window 2a of the infrared lens 2 can be made smaller, the infrared utilization range RU is expanded, and the infrared utilization efficiency is maximized. In contrast, in the comparative example in Fig. 10, the use of the concave axicon lens 16 causes the laser beam to continue expanding after passing through the concave axicon lens 16, so the laser reflecting mirrors 18 and 19 and the central window 15a of the infrared lens 15 cannot be made smaller, the infrared utilization range RU is narrowed, and the utilization efficiency is reduced.

[0034] In the embodiment in Figure 1, the infrared utilization efficiency in the infrared utilization range RU is approximately 2.38 times higher than that of the comparative example in Figure 10. Therefore, using a convex axicon lens 6 instead of a concave axicon lens 6 is extremely effective in improving the infrared utilization efficiency.

[0035] 1, the first and second laser reflecting mirrors 8 and 9 each have an irradiation direction adjustment mechanism for adjusting the irradiation direction of the aiming laser beam. Specifically, the first laser reflecting mirror 8 is rotatable around an axis (the central axis of the first mirror holder 7) parallel to the paper surface and vertical to the paper, as indicated by the arrow. The second laser reflecting mirror 9 is also rotatable around an axis (the central axis of the second mirror holder 11, an axis perpendicular to the combined coaxial axis RLX) perpendicular to the paper surface, as indicated by the arrow. Therefore, the ring laser RL irradiated onto the measurement target 10 can be adjusted along two axes, making it easy to align the infrared optical axis and the laser optical axis with the coaxial axis RLX. Furthermore, this adjustment mechanism allows the irradiated laser beam to be accurately aligned with the center of the second laser reflecting mirror 9 and the lens central window 2a, allowing the second laser reflecting mirror 9 and the lens central window 2a to be made smaller.

[0036] As described above, in the first embodiment, the laser reflecting mirror (first laser reflecting mirror) 8 is disposed at a position where the beam of the aiming laser beam, once narrowed by the convex cone-shaped lens 6, is near its minimum diameter, and the second laser reflecting mirror 9 is disposed to reflect the reflected light in the combined coaxial direction RLX, so that the reflected light is diffused in a ring shape on the surface of the measurement object 10. This ring-shaped aiming laser beam makes it easy to accurately adjust the measurement range RM on the measurement object 10, which changes depending on the measurement distance. At the same time, the laser reflecting mirrors 8 and 9 can be made smaller, so the entire radiation thermometer 1 can be made smaller, and the infrared utilization range RU can be expanded, thereby improving the infrared utilization efficiency.

[0037] In this embodiment, the first and second laser reflecting mirrors 8 and 9 each have an irradiation direction adjustment mechanism, but the irradiation direction adjustment mechanism of the first laser reflecting mirror 8 or the second laser reflecting mirror 9, or both of the irradiation direction adjustment mechanisms, may be omitted as necessary.

[0038] 7 is a cross-sectional view showing a main part of the second embodiment. In this embodiment, infrared energy is guided to an infrared sensor 27 by an infrared reflecting mirror 26, and a mirror center window 26a of the infrared reflecting mirror 26 is located near the minimum diameter of the beam of the aiming laser light once focused by a convex cone-shaped lens 25. The laser emitting unit 23 is located on the coaxial line RLX, and the infrared optical axis and the laser optical axis are combined on the coaxial line RLX. The aiming laser light irradiated in the coaxial line RLX passes through the mirror center window 26a of the infrared reflecting mirror 26 and the lens center window 21a of the infrared lens 21 and is diffused in a ring shape on the surface of the measurement object 10 to indicate the infrared measurement range RM. The other configurations are the same as those of the first embodiment.

[0039] Infrared rays emitted by the measurement object 10 are collected by the infrared lens 21, reflected by the infrared reflecting mirror 26, and received by the infrared sensor 22 to measure the temperature of the measurement object 10. The aiming laser light generated by the laser irradiation unit 23 on the coaxial line RLX is converted into parallel light by the collimator lens 24, and a ring laser RL is generated by the convex axicon lens 25 (conical lens).

[0040] The infrared lens 21 is made of a lens material such as silicon (Si) or germanium (Ge) that transmits infrared light but does not transmit visible laser light. A lens central window 21a made of a parallel plate of optical glass is formed in the center of the infrared lens 21 and is bonded to the lens material. The lens central window 21a transmits visible laser light but does not transmit infrared light.

[0041] Unlike the first embodiment, in which the infrared sensor 3 is arranged on the coaxial RLX, the laser irradiation unit 4 is not on the coaxial RLX, and the laser optical axis is synthesized into the infrared optical axis by first and second laser reflecting mirrors 8 and 9, the second embodiment arranges the laser irradiation unit 23 on the coaxial RLX, the infrared sensor 27 is not on the coaxial RLX, and the infrared light is guided by the infrared reflecting mirror 26. Even in this case, by using a convex axicon lens 25 and arranging this infrared reflecting mirror 26 near the position where the size of the laser beam is smallest, the size of the mirror center window 26a of the infrared reflecting mirror 26 can be reduced, and the efficiency of infrared light utilization can be maximized. Note that the infrared reflecting mirror 26 may have a reflection direction adjustment mechanism (not shown) that adjusts the reflection direction of the infrared light.

[0042] As described above, in the second embodiment, the mirror center window 26a of the infrared reflecting mirror 26 is disposed at a position where the beam of the aiming laser beam once narrowed by the convex cone-shaped lens 6 is near its minimum diameter, and is diffused in a ring shape on the surface of the measurement object 10, so that this ring-shaped aiming laser beam can easily and accurately adjust the measurement range RM on the measurement object 10, which changes depending on the measurement distance. At the same time, because the mirror center window 26a can be made smaller, the entire radiation thermometer 1 can be made smaller, and the infrared utilization range RU can be expanded, thereby improving the infrared utilization efficiency.

[0043] In each embodiment, a convex axicon lens having a convex conical surface is used, but instead of the convex conical surface, a convex polygonal pyramidal lens 31 having a hexagonal pyramidal surface as shown in Fig. 8 may be used. In this case, a beam of light consisting of multiple points arranged in a ring shape is generated, which similarly has the effect of indicating the infrared measurement range RM. Fig. 9 shows a laser RL1 generated by the convex hexagonal pyramidal lens 31, with six points arranged in a ring shape.

[0044] The present invention is not limited to the above-described embodiments, and various additions, modifications, and omissions are possible without departing from the spirit of the present invention. Therefore, such additions, modifications, and omissions are also included in the scope of the present invention. [Explanation of symbols]

[0045] 1: Radiation thermometer 2: Infrared lens 2a: Central lens window 3: Infrared sensor (thermopile) 4: Laser irradiation section 5: Collimator lens 6: Convex conical lens (convex axicon lens) 7: First mirror holder 8: Laser reflection mirror (first laser reflection mirror) 9: Laser reflection mirror (second laser reflection mirror) 10: Measurement object 11: Second mirror holder 20: Control unit 26: Infrared reflecting mirror 26a: Mirror center window RLX: Combined Coax RL: Ring laser RM: Infrared measurement range of the object being measured RU: Infrared range

Claims

1. A radiation thermometer that measures the temperature of an object by detecting infrared energy radiated from the object with an infrared sensor, an infrared lens for focusing and directing the infrared energy to the infrared sensor; a convex cone-shaped lens that first narrows the beam of the aiming laser light emitted from the laser irradiation unit and then diffuses it into a ring shape; and an optical system including a laser reflecting mirror and / or an infrared reflecting mirror that synthesizes an infrared optical axis and a laser optical axis coaxially toward a measurement object; a radiation thermometer in which the laser reflecting mirror or the central mirror window of the infrared reflecting mirror is positioned so that the beam of light once narrowed by the convex cone-shaped lens has a diameter close to its minimum at a position in the optical system where the aiming laser light is reflected by the laser reflecting mirror or where the aiming laser light passes through a central mirror window provided in the infrared reflecting mirror, and the beam of light of the aiming laser light is diffused in a ring shape on the surface of the object to be measured so as to indicate the measurement range of infrared rays emitted from the object to be measured.

2. In claim 1, A radiation thermometer in which a first laser reflecting mirror is disposed near the minimum diameter of the beam of light of the aiming laser light once narrowed by the convex cone-shaped lens, and the beam of light reflected from this first laser reflecting mirror is reflected by a second laser reflecting mirror disposed on the combined coaxial line and irradiated in the combined coaxial line direction, then passes through a lens center window provided in the infrared lens, and is diffused in a ring shape onto the surface of the object to be measured.

3. In claim 1, a radiation thermometer in which the infrared energy is guided to the infrared sensor by the infrared reflecting mirror, and a mirror center window of the infrared reflecting mirror is disposed in the vicinity of the minimum diameter of the beam of the aiming laser beam once narrowed by the convex cone-shaped lens, so that the combined aiming laser beam irradiated in the coaxial direction passes through the mirror center window of the infrared reflecting mirror and the lens center window of the infrared lens, and is diffused in a ring shape on the surface of the object to be measured.

4. In claim 2, a radiation thermometer, wherein the first and second laser reflecting mirrors each have an irradiation direction adjusting mechanism for adjusting the irradiation direction of the aiming laser light;

5. In any one of claims 1 to 4, A radiation thermometer, wherein the convex cone-shaped lens is a convex cone lens.

6. In any one of claims 1 to 4, A radiation thermometer, wherein the convex cone-shaped lens is a convex polygonal cone lens.

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