JPH081459Y2 - Isothermal control type calorimeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an isothermal control type calorimeter for measuring the power of light such as a laser, and more particularly to improvement of a light receiving part.

<Prior Art> As an isothermal control type calorimeter of this type, one having a configuration shown in FIG. 4 is known.

In the figure, reference numeral 1 denotes a heat absorber forming a sensor portion S, which is composed of a cylindrical body 3 having an inner surface coated with a light absorbing paint 2 and a heat transfer plate 5 having a heater 4 embedded therein. Reference numerals 6 and 6a are temperature difference detecting elements, and 7 is a thermoelectric cooling element. These elements are formed of Peltier elements having the same performance, and the heat transfer plate 5
It is fixed in a state of being sandwiched by the reference jacket 8.
In order to stabilize the temperature, the outer circumference of the reference jacket 8 has an intermediate jacket 9 and an outer jacket 10 as shown in FIG.
And the sensor portion S is surrounded by a triple jacket to form a light receiving head A. In addition, the cylindrical body 3
The heat capacity of the heat transfer plate 5 and the heat capacity of the reference jacket 8 are about 1: 1000, and the reference jacket 9 is larger.

Reference numeral 11 is a constant current source connected to the thermoelectric cooling element 7. 12
Is an amplifier that amplifies the output from the temperature difference detection elements 6 and 6a, and this output is input to the filter 13 and the voltmeter 16,
The output signal of the filter is input to the adder 14. on the other hand,
The output from the voltmeter 16 is the arithmetic unit 17, programmable power supply 1
It is input to the adder 14 via 8 and added to the output from the filter 13, and the output is output to the heater 4 via the square root calculator 15. Reference numeral 19 denotes a digital voltmeter, which measures the voltage V _H applied to the heater 4 and returns the measured value to the arithmetic unit 17. These circuit portions constitute a main body B for the light receiving head A.

In the above configuration, when the measurement light is not input,
The reference jacket 8 is kept at room temperature, and the thermoelectric cooling element 7 made of a Peltier element is constantly supplied with a constant current I _A from the constant current source 11 to constantly cool the heat transfer plate 5 side. In this case, the reference jacket 8 side will be heated,
Since the heat capacity of the reference jacket 8 is large and the heating amount of the thermoelectric cooling element 7 is small, the temperature of the temperature reference jacket 8 cannot be raised.

Therefore, in the apparatus shown in FIG. 4, the thermoelectric cooling element 7 and the constant current source
11 always acts to increase the temperature on the reference jacket 8 side and decrease the temperature on the heat absorber 1 side.

On the other hand, the temperature difference detection elements 6 and 6a are
The amplifier 12 amplifies the output to (mV level) and outputs it to the filter 13 and the digital voltmeter 16. After removing the noise (high frequency) component, the filter 13
The signal V _f is output to the adder 14. Digital voltmeter 16
The temperature difference .DELTA.p measured in (1) is applied to the arithmetic unit 17 and a predetermined arithmetic operation (this arithmetic operation is a known arithmetic operation for controlling so that the temperatures of the heat transfer plate 5 and the reference jacket 8 coincide with each other quickly) is performed. After that, the calculated value is applied to the programmable voltage source 18. Programmable voltage source based on this calculated value
The output V _{p of} 18 and the output V _f from the filter 13 are added by the adder 14
And added to the square root calculator 15, where (V _p +
V _f ) ^1/2 is calculated. The output of the square root calculator 15 is applied to the heater 4 to raise the temperature of the heater 4 and control the outputs of the temperature difference detecting elements 6 and 6a to zero.

Therefore, in the apparatus shown in FIG. 4, the thermoelectric cooling element 7 and the constant current source
Square root calculator for the heat transfer plate 5 cooled by the action of 11.
A voltage (current I) is applied to the heater 4 from 15 to heat the heat transfer plate 5, and the temperature of the heat absorber 1 and the temperature of the temperature reference jacket 8 are controlled to match.

In this state, when the laser light La to be measured is incident from the upper part of the cylindrical body 3, the heat absorber 1 absorbs the light and the temperature rises according to the optical power. The heat is conducted to the heat transfer plate 5, and a temperature difference is generated between the heat transfer plate 5 and the reference jacket 8 that are in a temperature equilibrium state. The temperature difference detecting elements 6 and 6a detect this temperature difference, and the square root operator 15 reduces the voltage value sent to the heater 4. Therefore, the temperature of the heater 4 decreases, and the temperatures of the heat transfer plate 5 and the reference jacket 8 match again.

<Problems to be Solved by the Invention> However, the calorimeter having the above-mentioned configuration is
The combination of the main body B and the main body B is fixed, and the light receiving heads A having different shapes depending on the small power, the large power, the spatial beam, the optical beam such as the optical fiber cannot be exchange-connected to the common main body B.

That is, when trying to measure a plurality of types of light powers having different light beam shapes, it is inconvenient to prepare a calorimeter in which light receiving heads corresponding to the respective light beam shapes are combined. .

The present invention has been made paying attention to such a point, and an object thereof is to provide an isothermal control type calorimeter in which light receiving heads having different shapes according to the shape of a light beam can be exchange-connected to a common main body. It is in.

<Means for Solving the Problems> The present invention, which solves the above problems, compares a heat absorber having a heater that absorbs the amount of heat of light to be measured and the temperature rise of the heat absorber with the temperature of the reference jacket. Temperature difference detecting means for detecting the temperature difference, a light receiving head including a memory in which correction data based on the equivalent error of the heat absorber and calibration resistance data of the heater are stored, and temperature difference detection of the light receiving head. Control means for controlling an electric signal applied to the heater so as to remove the temperature difference detected by the means, computing means for reading the data stored in the memory and performing a correction computation for the measurement result, and the computing means It is characterized in that it is composed of a main body including a display section for displaying the calculation result in 1. and a cable for connecting the light receiving head and the main body in a replaceable manner.

<Operation> In the present invention, the calculation means of the main body reads the data of the memory provided in the light receiving head through the cable in order to perform the correction calculation for the measurement result.

Thereby, the light receiving head can be exchange-connected to the common main body.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.
The same parts as those in FIG. 5 and FIG. 5 are designated by the same reference numerals and their repeated description will be omitted. In the figure, the light receiving head A
Between the intermediate jacket 9 and the outer jacket 10 is provided a memory 20 in which correction data based on the equivalent error of the heat absorber 1 and calibration resistance data of the heater 4 are stored. The arithmetic unit 17 of the main body B is provided with a display section 21 for displaying the measurement result of the optical power. C is a cable that connects the light receiving head A and the main body B in an exchangeable manner. The memory 20 is accessed from the arithmetic unit 17 via the cable C.

The operation of the apparatus thus configured will be described with reference to FIG. In FIG. 2, it is assumed that the laser light output from the stabilizing light source D is incident on the light receiving head A through the attenuator E and the shutter F.

In the first step of the measurement operation, the shutter F is closed,
No light is incident on the light receiving head A. In this state, the heater power is controlled so that the reference jacket 8 and the heat absorber 1 are in thermal equilibrium. The heater power consumption at this time is PH ₁
And

In the second step, the heater power is controlled so that the reference jacket 8 and the heat absorber 1 are in thermal equilibrium with the shutter F open. The heater power consumption at this time is PH ₂
And

As a result, the incident light power P _L is replaced with the heater power consumption difference (PH ₁ −PH ₂ ), and the incident light power P _L can be known by knowing PH ₁ and PH ₂ , but the heat absorber 1 Has an equivalent error. The equivalent error refers to a replacement error between a temperature rise upon incidence of optical power and a temperature rise due to a heater.

There is an error in the equivalent error due to the bottom surface portion of the heat absorber, the side surface of the cylinder, reflection leakage, etc., and the replacement ratio between the optical power and the power consumption is not completely 1, and P _L = E (PH ₁ -PH ₂ ). E is an equivalent error.

The equivalent error varies depending on the structure and surface state of the heat absorber, and each light receiving head A has a unique value.

Therefore, when a calorimeter is used as the standard optical power meter, the equivalent error E is individually evaluated and obtained,
The incident light power P is calculated from the values of PH ₁ and PH ₂ using the equivalent error E.
You will be asked for _L.

On the other hand, the heater power PH is where the control deviation becomes zero, is determined by the voltage V _R and the heater resistance value R _H, which is applied to the heater resistor.

The voltage V _R is measured by the voltmeter 19 at the heater resistance terminal portion in order to avoid the influence of the wiring resistance from the output end of the square root operator 15 to the heater resistance 4 terminal.

As for the heater resistance value R _H, it is necessary to measure the resistance value of each light receiving head A. Therefore, the heater resistance value R _H
Has a value peculiar to the light receiving head. Heater power PH is obtained by calculation of ^{_{PH = (V R) 2 /}} R H.

The heater resistance value R _H can be obtained, for example, immediately after the power is turned on by adding a highly accurate constant current source 22 to the main body B side as shown in FIG. That is, a constant current Ir in addition to the heater resistor R _H, the heater resistance R _H of this time
The voltage V _c at one end of is measured with a voltmeter 19. This allows
The resistance value R _{H of the} heater is obtained by R _H = V _c / I _r . With such a configuration, it is not necessary to have resistance value data in the light receiving head A.

<Effect of the Invention> As described in detail above, according to the present invention, it is possible to provide an isothermal control type calorimeter in which a light receiving head having a different shape depending on the shape of a light beam can be exchangeably connected to a common main body.

Further, when it is used as a standard device, it can be convenient for cross-checking the light receiving head.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is an operation explanatory diagram of FIG. 1, FIG. 3 is a configuration diagram showing an essential part of another embodiment of the present invention, and FIG. FIG. 5 is a configuration diagram showing an example of a conventional isothermal control type calorimeter, and FIG. 5 is a configuration diagram of a light receiving head. A: Light receiving head, B: Main body C: Cable, 20 ... Memory

Claims (1)

[Scope of utility model registration request] 1. A heat absorber which absorbs the amount of light to be measured and which has a heater, and a temperature difference detecting means for comparing the temperature rise of the heat absorber with the temperature of a reference jacket to detect the temperature difference. A light receiving head including a memory in which correction data based on an equivalent error of the heat absorber and calibration resistance data of the heater are stored; and a temperature difference detected by a temperature difference detecting means of the light receiving head. A control means for controlling an electric signal applied to the heater, a main body including a calculation means for reading out the data stored in the memory and performing a correction calculation for the measurement result, and a cable for connecting the light receiving head and the main body in a replaceable manner. An isothermal control type calorimeter characterized by being constituted by, and.