JP2002195879A - Isothermal control type laser calorimeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems in a conventional calorimeter that uncertainty is increased due to increased factors of uncertainty because a light receiving part for receiving laser light comprises a disk absorbent on a bottom part and a cylindrical absorbent for absorbing laser light reflected by the disk absorbent and thus equivalent evaluation of laser power is complicated, and that a light receiving element is hard to replace because it is integrated in the meter. SOLUTION: This isothermal control type laser calorimeter has an NiP absorbent 27 formed on a flat light receiving surface. The NiP absorbent absorbs 99.9% or more of received laser light as heat. A thermistor base 26 having the NiP absorbent is separable from a heater base 21 and the NiP absorbent 27 can be replaced on the occasion of checking its change with time, its deterioration, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isothermal control type laser calorimeter according to a laser power standard in measuring a laser beam.

[0002]

2. Description of the Related Art In recent years, techniques using laser light have been proposed in various fields such as optical communication using optical fibers. The laser output device used for these needs to accurately measure the absolute value of the laser output and adjust based on the laser standard. As a device for measuring the laser light, a laser calorimeter is generally known.
As the calorimeter, for example, there is one described in “Laser power standard by high-sensitivity laser calorimeter” (Takeumi Inoue et al., Electronic Technology Research Institute, Vol. 11 (1992), separate volume).

FIG. 5 shows a schematic configuration of the calorimeter. This calorimeter employs an isothermal control type, includes a thermistor 41 for equivalence evaluation and a heater 42 for isothermal control, a light receiving unit 43 for receiving incident laser light and converting it into heat, a light receiving unit 43 and a reference. Temperature jacket 4
4, a thermoelectric detecting element 45 [T] composed of a Peltier element or the like for converting a temperature difference into an electric signal, a thermoelectric cooling element 46 [C] for cooling the light receiving section 43, and a thermoelectric cooling element 4
Cooling power supply 47 for driving 6 [C], preamplifier 48 for amplifying the temperature signal output from thermoelectric detection element 45 [T], filter 49 for removing noise from the amplified temperature signal, and not shown. A digital multimeter 50 that indicates the output value of the preamplifier 48 to the computer;
Voltage source 51 controlled by a computer (not shown)
An adder 52 that adds the temperature signal from the filter 49 and the voltage signal from the voltage source 51; and a root amplifier 53 that controls the temperature of the isothermal control heater 42 based on the output signal of the adder 52. Is done.

The light receiving section 43 is formed integrally with a base portion 61a such as aluminum which has good heat conductivity and a cylindrical portion 61b provided on the base portion 61a. The lower side of the base portion 61a (the thermoelectric detection element 4
On the [5 [T] side), a central portion is cut off in a concave shape, and an isothermal control heater 42 is arranged. The cylindrical portion 61b
Heaters 62 and 63 for evaluation of the light receiving unit 43 are provided on the front and rear sides of the outer periphery of the cylindrical unit 61b, and a cylindrical absorber made of a black paint applied is formed on the inner wall 61c of the cylindrical unit 61b. A disk absorber made of black paint applied in the same manner is provided on the bottom (light receiving portion) 61d. The equivalence evaluation thermistor 41 is arranged at the center of the disk absorber at the bottom 61d.

[0005] The measurement by the calorimeter will be described. Before the measurement, the temperature of the light receiving unit 43 is the same as the temperature of the reference temperature jacket 44. First, a current to be applied to the thermoelectric cooling element 46 [C] is set in advance so as to be cooled by expected heat generation (measured value) by the laser beam, and
The temperature of No. 3 is lower than the temperature of the reference temperature jacket 44. The temperature difference generated at this time is determined by the thermoelectric detection element 45 [T].
The preamplifier 48, the filter 49, and the adder 5
The feedback control of the temperature of the heater 42 is performed through a control system including the second and root amplifiers 53. As a result, a temperature equilibrium is obtained again between the light receiving section 42 and the reference temperature jacket 44. However, the closed loop control deviation of the analog control system remains. Then, the voltage applied to the heater 42 at the time of the equilibrium is measured and processed by a computer. This reduces the control amount,
Control deviations can also be reduced. This operation is repeatedly performed until the control deviation reaches the noise level. When laser light is incident under such isothermal control conditions, the bias DC component of the corresponding heater is reduced, and the power of the incident laser light can be measured from the change.

[0006]

When the laser beam in the form of a beam is received by the light receiving portion 43 of the above-described conventional calorimeter, it is once incident on the bottom 61d of the light receiving portion 43.
Since the applied black paint has a certain degree of reflectance, the disk absorber cannot completely absorb the laser light, and the reflected laser light is absorbed by the cylindrical absorber.
Therefore, it is necessary to add what is absorbed by the cylindrical absorber to what is absorbed by the disk absorber. For this reason, the equivalent evaluation of the laser power becomes complicated, and causes of uncertainty increase, and this uncertainty greatly affects the measurement result.

The factors of uncertainty when measuring the absolute value of the optical power by the calorimeter are as follows: (1) The optical power related to the heat generation of the received laser beam and the D added to the thermistor.
Equivalence with C power (equivalent uncertainty), (2) Non-uniformity of light receiving surface sensitivity, (3) Control deviation, (4) DC measuring instrument (for heater power measurement), (5) Variation due to comparative measurement (light source) Output stability).

[0008] Among them, (1) the equivalent uncertainty includes the total reflectivity of the absorber, the substitution coefficient between the optical power and the DC power, the substitution coefficient between the DC power and the heater power applied to the thermistor, and the like. That is, it is the uncertainty associated with the determination of the correction coefficient K in Expression (1) described later.

An equivalent evaluation thermistor 41 is arranged at the center of the upper surface of the bottom portion 61d of the light receiving portion 43, and an absorber is formed so as to cover the thermistor 41.
Only e has a convex shape. For this reason, there is a problem that the surface sensitivity distribution at the center of the disk absorber is reduced.

Further, for example, when the deterioration occurs due to the aging, it is necessary to replace it. However, since the base portion 61a and the cylindrical portion 61b are integrally formed, the replacement including the isothermal control heater 42 is performed. Have to be a complicated task. Further, even if the components are replaced, the equivalent evaluation thermistor 41, the isothermal control heater 42, and the heaters 62 and 63 mounted on the light receiving unit 43 are renewed, so that the characteristic variation due to these components is caused. Work is also required, and replacement is not easy.

Therefore, the present invention has a simplified structure for receiving light with an absorber having a flat surface, the light receiving portion can be easily replaced, the uncertainty due to the shape of the light receiving portion is eliminated, and a highly accurate laser power standard is provided. It is an object of the present invention to provide an isothermal control type laser calorimeter which realizes the above.

[0012]

In order to achieve the above object, the present invention comprises a nickel-phosphorus compound film formed on at least one principal surface of a flat thin-film copper substrate, and absorbs an irradiated laser beam as heat. NiP absorption means, a point heat source for equivalence evaluation disposed on the non-light-receiving surface side of the thin-film copper substrate, and a hole for making the heat conduction path between the point heat source for equivalence evaluation and laser light the same. An isothermal control type laser calorimeter provided with a light receiving unit having a base unit mounted with the point heat source for equivalence evaluation attached to the thin film copper substrate. Further, the base portion including the NiP absorption means is detachably attached to a heater portion for controlling the isothermal temperature of the light receiving portion of the isothermal control type laser calorimeter with a medium having high thermal conductivity interposed therebetween. .

In the laser calorimeter of the isothermal control type having the above-described structure, the total reflectance is 0.1% or less (wavelength 0.4 to 0.4%) by the NiP absorption means formed only from the flat light receiving surface.
2 μm), and most of the received laser light is absorbed as heat. Further, the base portion provided with the light receiving surface is detachably mounted on the heater base with the medium interposed therebetween.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of a block configuration of an embodiment of an isothermal control type laser calorimeter according to the present invention. The laser calorimeter of the present embodiment employs an isothermal control type system, and the constituent parts except for the light receiving part which is the gist are substantially the same as the constituent parts of the calorimeter shown in FIG. 5 described above. Has become. FIG. 2 is a sectional view showing a detailed configuration of the light receiving element 1a (1b) of the light receiving section 1 in the laser calorimeter.

This calorimeter is roughly divided into two light receiving elements 1a, 1b having the same configuration for detecting the light to be measured and for compensating the pressure and temperature to obtain the same thermal response.
, A reference temperature base 2 to be described later provided with these light-receiving units 1, and light-receiving elements 1a and 1
It comprises an adder 3 for adding the respective outputs of b, and a control unit 4 for performing feedback control (isothermal control) on the light receiving unit 1 and performing arithmetic processing on the received laser light.

The control unit 4 includes a computer 5 for performing overall control and various arithmetic processing, a cooling current source 6 for driving a thermoelectric cooling element 23 [C] provided in the light receiving element 1a,
Preamplifier 7 for amplifying the temperature signal output from adder 3
A main amplifier 8 for performing arithmetic processing of the amplified temperature signal, a digital multimeter 9 for indicating the output value of the preamplifier 7 to the computer 5, and a heater 24 provided in the light receiving element 1a via the main amplifier 8. A heater voltage source 10 for outputting a heater voltage (a part of the compensated heater voltage) to [H]; a digital multimeter 11 for monitoring the compensated heater voltage output from the main amplifier 8; It consists of. Also, the main amplifier 8
Is a divider 12 for inputting an output value of the preamplifier 8 and an output of the heater voltage source 10, a filter 13 for removing noise from an output of the divider 12, and an output of the heater voltage source 10 to an output of the filter 13. And an adder 14 for generating a compensated heater voltage.

The light receiving element 1 is arranged in series with a heater base 21 made of a metal such as aluminum and arranged on the lower surface (second surface) side of the heater base 21 so that the electrical polarity is reversed. Thermoelectric detection element 22 composed of a Peltier element or the like for converting a temperature difference from temperature base 2 into an electric signal
[T] is arranged. In the present embodiment, the thermoelectric detection element 22 [T] has a frame shape or an annular shape, and a thermoelectric cooling element 23 [C] is disposed at the center.

As shown in FIG. 2, the light-receiving element 1 includes the heater base 21 and the thermoelectric detection element 22 [T] described above.
And a thermoelectric cooling element 23 [C] arranged at the center of the thermoelectric detection element 22 [T] for cooling the heater base 21 and the like.
And a heater 24 arranged on the bottom surface of a concave hollow portion formed at the center on the lower surface (second surface) side of the heater base 21, and arranged so as to cover the upper surface (first surface) side of the heater base 21. The indium sheet 25 having a thickness of, for example, about 0.2 mm for enabling the thermistor base 26 and the heater base 21 to be attached to and detached from each other, and a metal having high thermal conductivity, such as aluminum, having insulating properties on both sides by alumite treatment Thermistor base 26, a nickel-phosphorus compound (NiP) film formed on the surface of the thin-film copper substrate, and a NiP absorber 27 for absorbing laser light, and a back (non-light-receiving surface) side of the NiP absorber 27 A thermistor that is attached to the center and serves as a point heat source for equivalent evaluation to calculate the substitution coefficient by adding an accurate DC component output corresponding to the heat generated by absorbing the laser beam 28 to be composed of.

The light-receiving element 1 includes a reference temperature jacket 2
In the case of mounting, the NiP absorber 27 and the thermistor 28 are integrated by a fixing jig, a light receiving unit mounting cover (not shown) and spacers 29a and 29b formed of resin or the like pressed by a pressure ring. And the thermistor base 26 is pressed against the reference temperature jacket 2 side. Even without using an adhesive member by this pressing,
Thermistor base 2 with indium sheet 25 interposed
6 and the heater base 21 are attached to the reference temperature jacket 2 in a state of being pressed. Therefore, the thermistor base 26 and the heater base 21 can be easily separated simply by removing the light receiving element 1 from the reference temperature jacket 2.

The NiP absorber 27 is formed, for example, by
A nickel phosphorus compound (NiP) film is formed on the surface of the thin-film copper substrate, and the formed surface is roughened so as not to be reflected. When the present embodiment is performed, the NiP absorber 27 has been formed into a thin film of copper on a substrate by a known plating technique, vapor deposition, it may be used a thin film forming technique in semiconductor technology such as CVD or PVD. The NiP absorber 27 may be formed on both main surfaces of the thin-film copper substrate, or may be formed on one main surface.

Although the thickness of the thin-film copper substrate is set to 20 μm, the thickness is not limited to this. The thinner the thickness, the higher the accuracy with respect to the thermistor 28 and the flatness is ensured. It may be about 5 μm. In the present embodiment, the thin film copper substrate is used. However, it is needless to say that the present invention is not limited to this, and a metal having high thermal conductivity, such as aluminum, can be used instead. The indium sheet 25 has high heat conductivity,
Any member may be used as long as it acts so that the lower surface of the thermistor base 26 and the upper surface (first surface) of the heater base 21 are in close contact with each other. For example, a sheet made of a resin having high heat conductivity may be used.

A part of the thermistor base 26 facing the thermistor 28 disposed on the NiP absorber 27 is provided with a penetrating window having a diameter of 1 mm at the center in order to make the heat conduction path (heat path) of the thermistor 28 and the laser beam the same. (A hole) is provided, and a slot is formed through the hole so as to accommodate the lead wire of the thermistor so that the contact surface becomes flat even when the thermistor is mounted. In the present embodiment, the size of the opening is about 0.3 mm. Therefore, the size of the opening is preferably about three times as large as φ1 mm. The slit is provided for accommodating a lead wire connected to the thermistor body and flattening an adhesive surface. The slit is formed in accordance with the lead wire shape of the thermistor.

FIG. 3 is a diagram showing a cross-sectional configuration of the laser calorimeter main body of the present embodiment to which the light receiving section 1 is attached. This laser calorimeter body has a triple structure,
Reference temperature jacket 32, middle jacket 33 from inside
And the outer jacket 35 in this order.

The reference temperature jacket 32 covers a member having a large heat capacity to which the two light receiving elements 1a and 1b are attached, for example, a reference temperature base 2 made of copper (Cu), and a mounting surface side of the light receiving elements 1a and 1b. Light receiving unit mounting cover 31 having two windows 30 opened in front of each light receiving element
It is composed of Further, the intermediate jacket 33 is capable of storing the reference temperature jacket 32, has a window 34 opened at the front of the light receiving element 1a when stored, and is provided with an aluminum ( Al) or the like.

The outer jacket 35 accommodates the intermediate jacket 33 and can be opened and closed for opening and closing.
is formed of aluminum or the like to which a is attached. A beam adapter 37 is attached to the front side of the outer jacket 35 and has a light guide tube section 36 for guiding a beam-like laser beam to the window 34 of the intermediate jacket 33. In addition, outside the outer jacket 35,
A pedestal 38 for mounting on a stationary or measuring system,
A carrying handle 39 is provided.

These jackets are only provided with an optical path that is opened so that laser light is emitted from the outside to the front of the light receiving element 1a, so that extraneous external light does not enter from other than this optical path. The light receiving unit 1 is shielded from light, and is configured to shut off even heat so that a change in the outside air temperature does not affect the light receiving unit 1. In this embodiment,
Due to the triple jacket structure, the result is that the temperature stability around the light receiving section is 10 ⁻⁶ ° C. or less under an ambient temperature environment of 1 ° C./30 minutes.

Next, the operation of the laser calorimeter configured as described above will be described. The measurement principle is the same as that of the isothermal control type described in the section of the related art. First,
A constant current always flows through the thermoelectric cooling element 23 [C] of the light receiving element 1a, and the output of the thermoelectric detection element 22 [T] is "
Feedback control is performed as a drive voltage for the heater 24 provided in the light receiving element 1a with a predetermined gain through the main amplifier 8 so that the NiP absorber 27 and the reference temperature base 2 become equal to "zero".

The laser beam to be measured is a NiP absorber 2
7 is irradiated and absorbed, the driving voltage of the heater 24 decreases in order to maintain the isothermal control. Here, the incident light power Pl of the laser light can be expressed by Expression (1), where Ph1 is the heater power when the incident light power is off and Ph2 is the heater power when the incident light power is on. P1 = K (Ph1-Ph2) (1) K is a coefficient (correction coefficient) representing the equivalence between the power obtained by the laser beam and the power for driving the heater.
Ideally, it is "1".

Therefore, the heater 24 is previously measured with a calorimeter.
Is measured in advance, and the heater voltage at the time of light reception is measured to calculate Ph1 and Ph2, thereby obtaining the incident light power Pl of the laser light. Note that the correction coefficient K
For more information, refer to "Improvement of Calorimeter for Optical Power Measurement Using NiP Absorber" disclosed by the present applicant (IME-00-22, IEEJ Measurement Materials, Masahiro Miyawaki, Takeumi Inoue 2000.
6.29), and a detailed description is omitted here. This correction coefficient K is given by the following equation (2).

[0030]

(Equation 1)

Here, kd is a substitution coefficient between the optical power of the laser light absorbed by the NiP absorber 27 and the DC power applied to the thermistor 28, and kh is a substitution coefficient between the thermistor power and the heater power. kr is N
This is the total reflectance of the iP absorber 27.

Next, with respect to the uncertainty in measuring the absolute value of the optical power, which is a problem in the prior art, the low uncertainty in the reflectance measurement of the NiP absorber used in the present embodiment will be described. . Total reflectance kr of NiP absorber 27
Is measured by two methods, a method using a photodiode reflectivity measuring device and a method using an integrating sphere, and the uncertainty is evaluated from the measurement results.

First, a method using a photodiode reflectometer measures a large-area silicon photodiode (four 18 mm square) 63a, 6 as shown in FIGS. 4 (a) and 4 (b).
Photodetector (PD) combining 3b, 63c, 63d
A laser beam (850 nm) 64 is applied from the center of 63 to Ni
The light is irradiated to the P absorber 27, and the reflected light is measured by the photodetector 63. Table 1 shows the results.

[0034]

[Table 1]

Since the photodetector 63 receives a part of the reflected light from the NiP absorber 27, it is necessary to correct the measurement result. The ratio is indicated by the reflected light receiving rate Qr of the photodetector 63 shown in Table 1. The reflected light receiving rate Qr is based on the assumption that the NiP absorber 27 has a diffuse reflection characteristic, the distance d from the photodetector 63 to the NiP absorber 27, and the photodetector 6
3 was calculated from the light receiving area. As a result, the NiP absorber 2
7 had a total reflectance of 0.06 to 0.07%.

In the method using an integrating sphere, the reference reflector (9
9.3%) and the NiP absorber 27, the total reflectance was determined to be 0.07 ± 0.01%. The results are shown in Table 1. The total reflectance was 0.005%, which was consistent with the two measurement methods, and the standard deviation in the reflectance measurement of NiP was 0.02%.

Next, the equivalence between the optical power of the laser beam received by the isothermal control type laser calorimeter in the present embodiment and the DC power applied to the thermistor 28 will be described. To evaluate this equivalence, N
A thermistor is attached to the back surface of the light receiving surface of the iP absorber 27 as a point heat source. The equivalence between these is that the thermal resistance A between the light receiving surface irradiated with the laser beam and the thermoelectric detection element 22 [T]
And the thermal resistance B between the thermistor 28 and the thermoelectric detection element 22 [T]. However, since it is difficult to directly determine the thermal resistance, the heat capacities C of these heat sources are assumed to be equal, and the time constant of the thermoelectric detection element output is determined and evaluated.

Let the thermal resistance A be τd = CRd and the thermal resistance B be τd
Assuming that t = CRt, the replacement coefficient kd can be expressed by the following equation (3). kd = τt / τd (3) The uncertainty of the equivalence is obtained from the standard deviation of the time constant measurement. The measurement of the time constant is obtained as follows.

First, a current equivalent to 1.2 mW is applied to the calorimeter heater 24 and the thermoelectric cooling element 23 in this embodiment to perform isothermal control. After stabilization, a current of 1 mW is passed through the thermistor 28. After the output of the thermoelectric detection element 22 [T] was stabilized, the thermistor current was cut off, and the voltage drop of the output was measured. This voltage drop takes in data at high speed (at an interval of 0.044 seconds) by the data logger. An approximation formula is obtained by fitting the obtained data to an exponential function by the least square method, and a time constant for the DC power applied to the thermistor 28 is calculated from the approximation formula. Regarding the optical power of laser light,
The time constant is measured in the same manner. For example, Table 2 shows the results obtained by measuring four calorimeters.

[0040]

[Table 2]

As shown in Table 2, the replacement coefficient kd is
In each case, the result was close to "1" and the uncertainty was 0.03% or less. Table 3 shows an example of a correction coefficient in a calorimeter to which the present embodiment is actually applied.

[0042]

[Table 3]

Next, the equivalence of the DC power applied to the thermistor 28 and the drive power applied to the heater 24 of the isothermal control type laser calorimeter in this embodiment will be described. A constant power is applied to the equivalent evaluation thermistor attached to the back of the light receiving surface of the NiP absorber 27, and the driving power of the heater with respect to the DC power (point heat source) is measured. Here, Table 4 shows an example in which the measurement was performed at a measurement level of about 10 mW at two-minute intervals and the replacement coefficient kt was calculated.

[0044]

[Table 4]

As shown in Table 4, the standard deviation is 0.0
A very stable measurement result of 03% was obtained. as a result,
As shown in the total uncertainty in Table 5, the 632.8 nm 1
At 0 mW level, the expanded uncertainty is 0.05% (k = 2)
Is obtained.

[0046]

[Table 5]

In order to improve the accuracy of the optical power calibration, a NiP absorber having a very small reflectance is adopted for the light receiving section, a calorimeter with a devised structure is newly developed, and the uncertainty is evaluated comprehensively. Was. As a result, the total uncertainty is
It was reduced to 0.05% (k = 2), and a remarkably high accuracy was realized. This is used for calibrating the power meter for the laser beam and the optical fiber, so that the traceability can be improved with high accuracy.

The calorimeter according to the present embodiment described above has the following effects. First, by adopting the NiP absorber 27 on the light receiving surface (absorption surface) of the light receiving element 1, the total reflectance is 0.1% or less (wavelength 0.4%).
２2 μm). That is, 99.9% or more of the received laser light is absorbed as heat.

Secondly, since the thermistor base provided with the light receiving surface is attached to the heater base by being pressed against the indium sheet, the thermistor base and the heater base can be separated.

Therefore, by making the thermistor base and the heater base separable, and by making the front surface of the reference temperature jacket detachable, the light-receiving part is taken out and the change of the absorber using laser light with time is measured. It has become possible to replace only the thermistor base portion including the NiP absorber 27 at the time of confirmation and deterioration.

Third, since the light receiving element has only a flat light receiving surface, the effective light receiving diameter can be easily enlarged, and the size can be reduced in length.

In the conventional calorimeter, the reflectance of the black coating absorber (disk portion) is about 3%, and the absorber is surrounded by a cylinder, and the reflected light is absorbed in the cylinder. The uncertainty of power equivalence was relatively large. In addition, since the light receiving portion was bonded to the reference temperature jacket with an adhesive to form an integral structure, it was difficult to verify the change with time of each portion.

In order to solve these problems, the calorimeter according to the present embodiment has an extremely small Ni reflectance of 0.1% or less.
An absorber consisting only of a flat surface using a P absorber,
The measurement of the surface reflectance has made it possible to easily evaluate the reflection leakage accurately.

The calorimeter of this embodiment has a structure that can be used for optical fiber power measurement by converting the front part from a beam adapter to a fiber adapter. The usable fibers are multimode fibers (N
(A: 0.20), the aperture angle can be increased by increasing the effective light receiving diameter of the absorber to φ8 mm and removing the cylindrical absorber of the conventional light receiving unit.

[0055]

As described above in detail, according to the present invention, the light receiving portion has a simplified structure for receiving light with a flat surface absorber, the light receiving portion can be easily replaced, and the uncertainty due to the shape of the light receiving portion. And an isothermal control type laser calorimeter that realizes a highly accurate laser power standard can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a block configuration of an embodiment of an isothermal control type laser calorimeter of the present invention.

FIG. 2 is a diagram showing a detailed configuration of a light receiving element of the light receiving unit shown in FIG.

FIG. 3 is a diagram illustrating a cross-sectional configuration of a laser calorimeter main body to which a light receiving unit is attached.

FIG. 4 is a diagram for explaining a method using a photodiode reflectometer.

FIG. 5 is a diagram showing a schematic configuration of a conventional calorimeter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light-receiving part 1a, 1b ... Light-receiving element 2 ... Reference temperature base 21 ... Heater base 22 ... Thermoelectric detection element 23 ... Thermoelectric cooling element 24 ... Heater 25 ... Indium sheet 26 ... Thermistor base 27 ... NiP absorber 28 ... Equivalent evaluation Thermistor

Continuing from the front page (72) Inventor Takeumi Inoue 1-4-1 Umezono, Tsukuba, Ibaraki Pref.

Claims (4)

[Claims] An NiP absorption means comprising a nickel-phosphorus compound film formed on at least one main surface of a flat thin-film copper substrate, for absorbing irradiated laser light as heat, and a non-light-receiving surface side of the thin-film copper substrate The equivalence evaluation point heat source disposed on the thin film copper substrate is formed with a hole for making the heat conduction path between the equivalence evaluation point heat source and the laser beam the same, and attached to the thin film copper substrate. An isothermal control type laser calorimeter characterized by mounting a light receiving section having a base section on which a laser beam is mounted. 2. The base including the NiP absorbing means detachably with a medium having high thermal conductivity interposed therebetween with respect to a heater provided for the light receiving section of the isothermal control type laser calorimeter to perform isothermal control. The isothermal control type laser calorimeter according to claim 1, wherein a part is mounted. 3. A laser calorimeter mounted on a reference temperature jacket for measuring received laser light, wherein a nickel phosphorus compound (NiP) is formed on a flat thin film copper substrate surface.
NiP for forming a film and absorbing the received laser light
An absorber, a thermistor for equivalence evaluation arranged at the center of the non-light-receiving surface side of the NiP absorber for adding a DC component output corresponding to heat generated by absorbing the laser beam to obtain a substitution coefficient; Is made of an insulated metal having a high thermal conductivity and adheres to the NiP absorber except for the thermistor portion, a heater base made of a metal having a high thermal conductivity, and a second surface side of the heater base A heater disposed on the bottom surface of the concave hollow portion formed in the heater base; an indium sheet interposed between the non-light receiving surface side of the thermistor base and the first surface of the heater base to conduct heat; A thermoelectric detection element that is arranged on the second surface side of the thermoelectric detection element and converts a temperature difference from the reference temperature jacket to be attached into an electric signal; A thermoelectric cooling element for cooling the heater base; and a laser power measurement based on the laser light received by the NiP absorber by isothermal control of the light receiving unit by feedback of the light receiving unit. When the light receiving section is mounted on the reference temperature jacket by a fixing jig, by pressing from the fixing jig, the thermistor base and the heater base are interposed with the indium sheet interposed therebetween. Wherein the thermistor base and the heater base are separated when the fixing jig is removed. 4. The laser calorimeter of the isothermal control type,
In order to obtain the same thermal responsiveness for detecting the light to be measured and for compensating the pressure and temperature, a second compensation absorber having the same configuration as the light receiving unit is further provided. Item 4. An isothermal control type laser calorimeter according to item 3.