JPH03122532A - Light power sensor - Google Patents

Abstract

PURPOSE:To improve sensitivity by a method wherein each thermocouple piece of a plurality of thermocouples arranged in series on a substrate is laminated with an insulating layer interposed. CONSTITUTION:alpha Ge is deposited on the whole of the surface of an alumina substrate 4, so that a pattern of a thermocouple element (a) having a hot contact of 7mmphi and a cold contact of 16 mmphi be formed. Ta2N is sputtered for a resistance of a heater 2 for calibration on the back side of the substrate 4, and first an NiCr alloy and then Au are evaporated sequentially and patterned thereon as electrodes for the heater, so that the resistance shaped in a ring and the electrodes thereof be laminated. The resistance of this heater for calibra tion is adjusted to be prescribed value by heat treatment. On the thermocouple element (a) in the surface, an SiNx layer and an SiO2 layer are laminated and patterned, so that an insulating layer 8 be formed. An NiCr alloy is evaporated on the whole of this layer and patterned, so that a thermocouple element (b), a heat-equalizing film and an electrode be formed. A copper leaf and an electroless Ni P plating layer are laminated on the heater 2 for calibration on the back side and a light-sensing body subjected to a blackening process is bonded thereon.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to an optical power sensor, and more specifically to a photoreceptor that absorbs incident light and converts it into heat, and a thermocouple that measures the converted heat as thermoelectromotive force. The present invention also relates to an optical power sensor including a calibration heater that calibrates the detected thermal energy of a thermocouple.

[Prior art 1] Fig. 3 is a back view of an optical power sensor conventionally used for measuring optical power, and a plan view showing the arrangement pattern of thermocouple groups. A cross-sectional view is shown.

In FIG. 4, a photoreceptor 31 as a sensor and a calibration heater 32 are bonded onto a substrate 34 with an adhesive, and on the opposite side of the substrate 34 there is a group of thermocouples (thermobar , il) is attached.

The thermocouple group, as shown in FIG.
Hot junctions 36 are arranged, respective thermocouples are arranged radially, and adjacent thermocouples and cold junctions 37 are connected in series to detect thermoelectromotive force.

The photoreceptor is usually a copper foil coated with a black coating, and focusing was used as the black coating. A temperature distribution calibration film 35 is adhered to the back surface of the substrate, in a portion corresponding to the photoreceptor, to make the temperature distribution uniform and to make the electromotive force of the high-temperature contacts of several sub-thermal lightning pairs arranged around it uniform. ing.

As a photoreceptor, an all-black film has a low total reflectance, is easily peeled off due to mechanical vibration or friction, and also has the problem of absorbing moisture and increasing the reflectance under high-temperature conditions.

In contrast, a black film developed by the inventors (patent application filed in 1983)
-231761 and Japanese Patent Application No. 6:1-231760) is obtained by forming an electroless plating film of nickel-phosphorous alloy and oxidizing it, and its total reflectance is 0.2. %, and has excellent performance in that its light absorption properties have little wavelength dependence.Moreover, it has sufficient strength, so it is difficult to peel off due to mechanical vibration or friction, and is not affected by ambient temperature conditions. It has the advantage of not absorbing moisture easily.

[Problem to be solved by the invention 1 When the above nickel-phosphorus black film is used as a sensor for measuring optical power, in order to increase its sensitivity, the number of thermocouples of the thermopile that measures the heat generated in the photoreceptor should be increased as much as possible. It is preferable to increase the amount.

However, in conventional optical power sensors, the fourth
As shown in the figure, thermocouples 1, for example bismuth and antimony, were arranged adjacent to each other by vacuum evaporation on the back surface of a substrate 34, and a hot junction 36 and a cold junction 37 were connected in series to form a thermomobile. Therefore, when the number of thermocouples is increased, the width of the thermocouple wire becomes extremely narrow, which increases the resistance, so there is a limit to increasing the number of thermocouples, and it has therefore been difficult to improve sensitivity.

The object of the present invention is to provide such an optical power sensor,
The purpose of the present invention is to provide an optical power sensor with excellent sensitivity.

[Means for Solving the Problems 1] The present invention solves the above problem by arranging the metals constituting a thermal lightning pair adjacently on a substrate, but by arranging them in layers with an insulating layer interposed therebetween. It is resolved.

That is, the present invention provides an optical power sensor comprising a photoreceptor that absorbs incident light and converts it into heat, a thermocouple that detects the converted heat as a thermoelectromotive force, and a calibration heater that calibrates the detected thermal energy of the thermocouple. The present invention provides an optical power sensor characterized in that thermocouple pieces of a plurality of thermocouples arranged in series on a substrate are laminated with an insulating layer interposed therebetween.

FIG. 1 shows an arrangement pattern of a thermocouple group in an embodiment of the optical power sensor of the present invention, and shows a stacked state with a part of the stacked body removed. FIG. 2 is a sectional view taken along line A--A in FIG. 1.

In the optical power sensor of the present invention, the arrangement pattern of the thermocouple group is performed as follows.

First, thermocouple elements are arranged radially around the heat-uniforming film 5 of the substrate 4, and then an insulating layer 8 is placed over the thermocouple elements, leaving the hot junction part 6 and the cold junction part 7 of the thermocouple element. Cover with Furthermore, the other element a of the thermocouple is laminated thereon, and its hot junctions 6a and 6b are joined to form a thermoelectric pair. In this case, the cold junction part 7a of this thermal lightning pair element a is directly joined to the cold junction part 7b of the adjacent thermal lightning pair element A.

That is, as shown in FIG. 1, the side part of the cold junction part of one element a of the thermocouples stacked with the insulating layer 8 in between protrudes toward the adjacent thermal lightning pair to form a joint part 7a. , are directly laminated and connected to the protruding joint portion 7b of the element of the adjacent thermocouple.

On the other hand, the cold contact portion on the side where bonding is not performed forms a pattern in which each element is cut out so that it does not come into contact with the bonding portion of other elements. Terminals 9 and IO for measuring thermoelectromotive force are provided at both ends of the series-coupled thermocouple group, respectively.

The insulating layer 8 that insulates the thermal lightning couple elements a and b is approximately disk-shaped except for the hot junction, and only the portion of the outer periphery corresponding to the cold junction junction 7 of the thermal lightning couple element is missing. It is formed into a pattern with recesses.

The substrate of the optical power sensor of Fujimoto's invention has insulating properties, and examples of the material include mica, ceramics, glass, mylar, and the like. Here the thickness is 30-601I+
n alumina was used.

As the photoreceptor used as the optical sensor element in the present invention, any photoreceptor can be used as long as it absorbs light and converts the energy into thermal energy.

In general, a thin film of black-treated metal with a small heat capacity is used, and it may be either the above-mentioned all-black coating or electroless nickel/phosphorus plating with a black coating, but it is difficult to use due to sensitivity and usage as a sensor. From the viewpoint of strength, a copper thin film with electroless nickel phosphorus plating treated with a black coating having extremely low total reflectance is preferred, especially as disclosed in Japanese Patent Application No. 63-2317.
60 and 63-2:11761, metal thin films having a black nickel-phosphorus alloy coating are preferred.

Although the dimensions of the photoreceptor are arbitrary, for example, a circular copper foil having a diameter of 6 mm and a thickness of 20 μm is plated with electroless nickel/phosphorus to a thickness of 50 μm, and a black film is formed by oxidation treatment. This photoreceptor may be glued onto the calibration heater, or an insulating film may be provided on the calibration heater, and the surface may be coated with a copper layer, electroless nickel/phosphorous plating, etc. by plating, vapor deposition, etc. The layers may be laminated and the surfaces thereof may be subjected to blackening treatment.

Calibration is performed using the amount of electricity required to heat the thermoelectromotive force heater, which is placed between the photoreceptor and the substrate and detected by a group of thermocouples.

The material of the heater is arbitrary, but tantalum nitride (Ta, N1
A conductive wire is drawn out from both ends of the ring-shaped pattern.

The soaking film is laminated on the opposite side of the substrate that corresponds to the photoreceptor.
Metal films with good thermal conductivity, such as gold or copper, are laminated using a method such as vapor deposition in a disc-shaped pattern that is approximately the same size as the photoreceptor. The heat generated in the photoreceptor is evenly transferred to the hot junctions of the thermal lightning pairs arranged around the heat-uniforming film.

The components of the Yukozuki thermocouple are formed by vapor deposition or CVD.
It is laminated on a substrate by means such as. As thermal lightning protection material,
B1-5b, Au-αGe, etc. are used, but gold (Au
) and amorphous germanium (αGe) is preferred.

In this case, after an αGe pattern is laminated on the substrate as a thermocouple element, an insulating layer pattern and an Au pattern with a Ni-Cr base as the thermocouple element a are successively laminated.

Lamination of these patterns is performed using a combination of lamination methods such as vapor deposition, sputtering, and CVD, resist patterning, and etching, depending on the respective materials.

Silicon nitride and silicon oxide can be used as insulating materials, but coating with one type of insulating material tends to cause insulation defects due to pinholes, etc., so it is recommended to have a multilayer structure with two or more types of materials. Preferably, when the thermal lightning couple element a is laminated after being coated with an insulating layer,
The hot junctions are joined and the cold junctions are coupled in series in the part where there is no insulating layer, thereby forming a thermocouple group.

[Example 1 Examples of the present invention will be shown below, but the present invention is not limited by these Examples.

Example 1 12 having the shape and pattern shown in FIGS. 1 and 2
An optical power sensor with a pair of thermocouple groups was fabricated.

α was applied to the surface of the alumina substrate 4 with a thickness of 5 ha by CVD.
Ge was deposited to a thickness of about 2 am on the entire surface, and a pattern of a thermocouple element a having a hot junction diameter of 7a+mφ and a cold junction diameter of 161101 as shown in FIG. 1 was formed by photoetching.

Ta is used as the resistance of the calibration heater 2 on the back side of the alumina substrate.
About 0.11101 aN was sputtered, and then a NiCr alloy 500 was first applied as a heater electrode (not shown).
Then, AullIn+ was sequentially deposited, patterning was performed twice by photoetching, and ring-shaped resistors and their electrodes were laminated. The resistance of this calibration heater is adjusted to a predetermined value through heat treatment.

On the thermocouple element a on the front surface, a SiN m layer of 0.2 am and a SiO□ layer of 0.51111 mm were sequentially laminated in two layers by CVD, and a pattern of the insulating layer 8 was formed by photoetching.

Furthermore, NiCr alloy (500 people) and Au (l
11 ml of the solution was sequentially deposited over the entire surface, and patterns of a thermocouple element, a soaking film, and an electrode were formed by photoetching.

There is a 20 μm copper foil and 3011 on the calibration heater on the back side.
A 6-order diameter photoreceptor obtained by laminating a 1t+ electroless nickel-phosphorus plating layer and blackening the surface was adhered.

Comparative Example 1 As an example of a conventional product, an optical power sensor having six thermocouple pairs shown in FIG. 3 was manufactured.

The photoreceptor, the calibration heater, the substrate, and the thermocouple element ab are the same as in Example 1, and the thickness and width of the thermocouple element are also substantially the same as in the example. They were not stacked with an insulator in between, but were placed adjacent to each other on the substrate and connected in series as shown in FIG.

Comparative Example 2 The structure was the same as that of Comparative Example 1 except that the number of thermocouples was 12. That is, the widths of thermocouple elements a and b were approximately half.

The following table shows a comparison of the above 31Φ optical power sensors.

Table [Function and Effect 1] The optical power sensor of the present invention stacks the thermal lightning pair elements of the thermocouple group via an insulating layer, so the logarithm of the thermal lightning pair can be increased and the sensitivity of the detected thermoelectromotive force can be increased. You can make one hit. Furthermore, when the logarithm is not increased, the width of the thermocouple element can be made wider, and the resistance value for thermoelectromotive force measurement can be lowered. In either case, this has the effect of reducing measurement noise on the measured value of thermoelectromotive force, making it possible to measure optical power at a lower level than in the past.

Procedural amendment document February 16, 1990

Claims (1)

[Claims] (1) An optical power sensor consisting of a photoreceptor that absorbs incident light and converts it into heat, a thermocouple that detects the converted heat as thermoelectromotive force, and a calibration heater that calibrates the detected thermal energy of the thermocouple. An optical power sensor characterized in that each thermocouple piece of a plurality of thermocouples arranged in series is laminated with an insulating layer interposed therebetween.