JPS58150831A - Solar beam incidence factor measuring apparatus for artificial satellite - Google Patents

Abstract

PURPOSE:To enable the measurement of an incidence factor of solar beam by obtaining an output ratio from a combination of two photodetectors each having a measuring diffusion reflector plate as view with the intensity of the solar beam as reference value. CONSTITUTION:Light from a pulse light source 2 driven by a pulse power source 8 irradiates an artificial satellite 1 to be measured with a reflector 3. A small measuring diffusion reflector plate 4 is placed at a preset measuring point. As the angle between the normal of the diffusion relfector plate 4 and the direction of an observing point therefrom and the distance between the diffusion reflector plate 4 and the observing pont are known from the arrangement of the measuring system, a totalized incidence value is obtained by measuring the intensity reflected light from the reflector plate 4. A photo detector 5 has the measuring diffusion reflector plate 4 as view and is set so as to admit no light from others. The incidence factor of solar beam is defined as totalized incidence value at a measuring point when the intensity of the solar beam is set at 1. Therefore, the incidence factor of the solar beam can be obtained by determining the ratio between the output of the photo detector 5 having the diffusion reflector plate 4 as view and the output of a photo detector 7 having a calibrating diffusion reflector plate 6 as view.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new device for measuring the optical characteristics of an artificial satellite, and its purpose is to measure the coefficient of sunlight incident on each part of two artificial satellites.

In order for the satellite mission to be successful.

In the space environment, the temperature of the JFR onboard equipment and each part of the satellite must be within the required range.

To validate thermal design and manufacturing.

Space environment tests are conducted at each stage of satellite development, namely the engineering model, grototype model, and flight model stages. The test equipment examines whether the temperature distribution approximates the predicted temperature distribution and whether the models operate normally when exposed to radiation equivalent to sunlight in a high vacuum and extremely low temperature environment. 10 for that
``It has a high vacuum that can be evacuated to over mmHg.

A shroud is provided near its inner wall which is cooled to about 20°K. Instead of sunlight, a pseudo-sunlight irradiation device consisting of a set of xenon lamps of several tens of kilowatts and an optical system, or an array of high-output infrared lamps is used.

In general, the absorptivity and reflectance of the surface of an object for light and thermal radiation differ depending on the wavelength of the electromagnetic waves contained in these radiations, and also vary depending on the directions of incidence and reflection.

The radiation from a xenon lamp approximates the solar spectrum fairly well, and the optics provide a parallel beam of light. Therefore, radiation from the sun can be approximated as a pseudo sunlight irradiation device. However, manufacturing a large-sized irradiation device based on this method is technically and economically difficult, and requires a great deal of effort for operation and maintenance. On the other hand, the spectral distribution of radiation from an infrared rung train is biased toward longer wavelengths compared to solar radiation, and the directionality is also diffuse. Although it does not approximate solar radiation, it is relatively easy to manufacture a large-scale device that uses radiation to generate heat. Currently, the standard space environment test device is one equipped with an irradiation device using a xenon lamp and an optical system, and many devices equipped with an irradiation device using an array of infrared lamps are manufactured for each of these devices. Detailed tests are being conducted to confirm this.

Let's summarize these space environment tests.

It can be said that the satellite at each stage of development is placed in a high vacuum, extremely low temperature environment, and the temperature distribution is measured by irradiating it with simulated sunlight. In other words, the aim is to investigate how an artificial satellite absorbs sunlight and the amount of heat generated by it is emitted into space in the form of thermal radiation.

However, according to the theory of radiant heat transfer, the spectral band of sunlight and the spectral band of thermal radiation can be considered separately in this radiant energy flow n. In the thermal design of satellites, we step-by-step predict the amount of sunlight incident on each part, predict the heat generation distribution due to the absorption of sunlight, and predict the temperature distribution due to this heat generation distribution and heat generation from other causes. There is.

The amount of sunlight incident can be immediately determined by knowing the sunlight incident coefficient, which is an optical property of the artificial satellite. Therefore, by measuring the sunlight incidence coefficient, you can analyze the temperature distribution measurement results from the simulated sunlight irradiation test, set the irradiation conditions when using an infrared lamp array, and examine the validity of the design and manufacturing method. You can obtain useful power information.

The present invention provides a means for simply and accurately measuring the sunlight incidence coefficient based on this principle. In other words, if the purpose is to measure the solar incidence coefficient, the two satellites should be placed in a high vacuum.

There is no need to place it in an extremely low temperature environment, and there is no need for a powerful simulated sunlight irradiation device to maintain the temperature.

It can be measured under normal laboratory conditions.

Furthermore, since it is better to perform irradiation in between to prevent the temperature of each part from rising, a low-output irradiation device may be used.

In the past, there have been proposals for measuring the sunlight incidence coefficient, but since this method uses natural sunlight directly, there are strict requirements regarding the installation location and weather conditions.
It has not yet come into general use. This invention is particularly designed for use in indoor measurements with a lighting device.

Hereinafter, the content of this invention will be explained with reference to examples. Figure 1 is a conceptual diagram showing the configuration of the device, where (1) is the artificial satellite to be measured, (2) is the pulsed light source, and (3) is the optical system to obtain a wide cross-sectional parallel beam. For example, a parabolic mirror, (
4) is a measurement diffuse reflector placed at the measurement point, (5) is a photodetector whose field of view is the measurement diffuse reflector (4), (6) is a calibration diffuse reflector, and (7) is a calibration plate. A photodetector whose field of view is the diffuse reflection plate (6).

(8) is a pulse power supply, (9) is a signal processing device, and Q
l is an electronic computer.

The light emitted from the pulsed light source (2) driven by the pulsed power source (8) is sent to the artificial satellite (to be measured) by the optical system (3).
1) A cross-sectional area (approximately 2 in diameter) large enough to irradiate
~7 mφ).

The parallelism of the light beam depends on the size of the light source (2) and the optical system (3)
By choosing the size appropriately, it is kept at about 9.3 milliradians, corresponding to the parallelism of sunlight.

Now, the light in the luminous flux can be incident on each part of the surface of the second artificial satellite (1) directly or after being reflected from other parts of the surface. There are parts where both direct light and reflected light enter, parts where only one of them enters, and parts where neither of them enter. The number of reflections is not limited to just one. The intensity of reflected light depends on the angle of incidence of the incident light, the surface characteristics of the reflecting surface, and the direction from the reflecting surface, and it is generally difficult to obtain it analytically with sufficient accuracy, so knowing its contribution is important in measurement. This is an important item.

Therefore, a small diffuse reflection plate (4) for measurement is placed at the measurement point. The reflection from the diffuse reflector (4) is diffuse, and does not depend on the relative relationship between the direction of the observation point where the reflected light is strong and the angle of incidence of the incident light, but the relationship between the normal of the reflecting surface and the direction of the observation point. related to the angle of This is because the angle between the normal line of the measurement diffuse reflection plate (4) and the direction of the observation point and the distance between the two are known based on the arrangement of the measurement system.

By measuring the intensity of the reflected light from this reflection plate (4), the total incident amount including direct light and light reflected from other surfaces can be obtained. Photodetector (5)
The field of view ν is the diffuse reflection plate (4) for measurement, and the surface characteristics of such a reflection plate (4) are different from the original reflection characteristics at the measurement point. This affects the exchange of reflected light between the various parts of the satellite's surface, but since the area is sufficiently small compared to the total surface area, this effect can be ignored.

The reflected light from the calibration diffuse reflector (6) similarly affects the incident light, but this n is also sufficiently small.

The sunlight input coefficient is defined as the total amount of incidence on the measurement point when the intensity of sunlight is 1. Therefore, by taking the ratio of the output of the photodetector (5) whose field of view is the diffuse reflection plate for measurement (4) and the output of the photodetector (7) whose field of view is the diffuse reflection plate for calibration (6), The incidence coefficient is determined. This is performed by a signal processing device (9) for this purpose. On the other hand, the intensity of light from the optical system (3) is calibrated using the output of the photodetector (7), and by making this equal to the irradiation intensity of sunlight, the amount of sunlight incident on the measurement point is determined. You can also do that. The sunlight incident coefficient and simulated sunlight incident amount measured at each point on the surface are calculated using an electronic computer 01 for convenience of use.
Store in.

FIG. 2 is a diagram showing an example of a pulsed light source (2) and an optical system (3) for obtaining a wide cross-sectional area parallel light beam.
υ is the light source, (a) is the support mechanism for the light source, and (3) is the animal surface mirror. A xenon gas discharge flash lamp is used as a light source (2), and pulsed light is repeatedly generated by a pulsed power source (8). The spectral distribution of the emitted light from the xenon lamp closely approximates the spectrum of sunlight, and sufficient peak light output can be obtained. The light source (2) is placed at the focal point of the animal mirror (3), so that the symmetry axes of both mirrors coincide.

The parallelism of the reflected light from the animal mirror (3) is given by a/f, where d is the effective diameter of the light source (2) and f is the focal length of the parapet surface. Now, if d is set to about 3 crn, d/f<0.01 radian, which is equal to the parallelism of sunlight, can be obtained. The part of the light beam that hits the light source (2) and its support mechanism (1) is blocked from the artificial satellite (1) that is the measurement target, but this is about 00001 square meters with respect to the total cross-sectional area of the light beam. It can be completely ignored.

Fig. 3 is a diagram showing another embodiment of the light source (2) and optical system (3), in which (21A) and (21B) are pulse lasers, (2) is a mirror surface for laser switching, and (C) is a beam diameter. Magnifying lens system.

04) is a random phase plate, (3I is a support rod, (31
) is an elliptical convex mirror, and (32) is a spherical mirror.

This is because the output light from a laser is almost monochromatic.

Those having different oscillation wavelengths (21A) and (21B) are used in combination. 3 points from the sunlight spectral band 1 For example 044,05? and 0.75 μm are selected, and two to three dye lasers such as rhodamine, which have a wide range of single oscillation, are combined and used by switching with a laser switching mirror (2). , in this example, three colors are switched,
Mix 3 colors.

It may also be irradiated. Moreover, a semiconductor laser or a solid-state laser can also be used instead of a two-dye laser. The output beam from the laser is narrow, making it difficult to manufacture small reflecting mirrors.
This is expanded to an effective diameter of about 3 crrLφ through a lens system (c). Furthermore, since coherent light and non-coherent light interact differently with substances, the light exiting the lens system 231 is made non-coherent by the random phase plate Q(a).

In order to obtain a luminous flux with the required cross-sectional area, an elliptical convex mirror (61) is used as a small reflecting mirror and a spherical mirror (61) is used as a main reflecting mirror.
32) is used in combination with the Cassegrain method. Since the main reflecting mirror (32) is a spherical mirror, it is easier to manufacture than an animal-shaped mirror.

But instead of a combination of spherical and elliptical mirrors.

A combination of large and small confocal animal mirrors may also be used.

FIG. 4 shows the configuration of the main parts of a further improved embodiment. 0
υ and a are synchronous detectors. The light source (2) is driven repeatedly at a constant cycle by the pulse power source (8), and in synchronization with this pulse, the output of the detector (5) (71) is detected to separate and measure the surrounding optical noise. In addition, instead of synchronous detection, the intensity or integrated intensity of two individual pulses may be measured.This method also allows the separation of ambient optical noise.In terms of accuracy, synchronous detection is superior to synchronous detection. Although inferior, accuracy can be improved by averaging a large number of measurements.

As another use of this device, it is possible to use this device to measure the performance of a solar cell system mounted on a satellite.

As described in detail above, this invention provides a point-like pulsed light source with a light spectrum that approximates that of sunlight, a point-like pulsed light source that has a large cross-sectional area that is large enough to irradiate the entire satellite with the luminous flux emitted from this light source, and a an optical system that spreads the beam into a parallel light beam with parallelism approximating the parallelism of , a small-area measurement diffuse reflector disposed on the irradiated surface of the above-mentioned satellite, and a first light whose field of view is only this reflector. a detector, a small-area calibration diffuse reflection plate disposed in the optical system, a second photodetector whose field of view is only this reflection plate, and the first photodetector. It is equipped with a signal processing device that compares the detection value of the second photodetector and calculates the sunlight incidence coefficient of the area where the measuring diffuser of the artificial satellite is installed, and uses optical pulses. In addition to small light source lamps and pulsed lasers, it is possible to determine the sunlight incidence coefficient and simulated sunlight incidence under normal laboratory conditions1.
Measurements of optical properties of artificial satellites are performed economically.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure is a detailed diagram of the pulsed light source, and FIG. 3 is a conceptual diagram showing the configuration of another embodiment of the pulsed light source and an optical system for obtaining parallel light flux.
FIG. 4 is a block diagram showing the configuration of main parts of another embodiment of the present invention. In the figure, (1j is an artificial satellite, (2) is a pulsed light source, (3) is a reflector, (4) is a diffuse reflector for measurement, (5)
, (71 is a photodetector, (6) is a diffuse reflection plate for calibration,
(8) is a pulse power supply, (9) is a signal processing device, αO is an electronic computer, and 0υ. α) is a synchronous detector, (21A) and (21B) are pulse lasers, (A) is a mirror surface for laser switching, c23 is a lens system, CI'4) is a random phase plate, (31) is a left circular convex mirror, ( 52) is a spherical mirror. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Shin Kuzuno - (1 other person)

Claims (4)

[Claims] (1) A point-like pulsed light source with a light spectrum that approximates sunlight, and the light emitted from this light source! l. An optical system that spreads the beam into a parallel beam with a cross-sectional area large enough to electrically seal the entire satellite and a parallelism approximating that of sunlight; Diffuse reflector for area measurement, first with only this reflector as field of view
a photodetector, a small-area calibration diffuse reflection plate disposed in the optical system, a second photodetector whose field of view is only this reflection plate, and the first photodetector. The solar light incidence coefficient of the artificial satellite is equipped with a signal processing device that compares the detected values of the second photodetector and calculates the solar light incidence coefficient of the area in which the measurement diffuser of the artificial satellite is disposed. measuring device. (2) The sunlight incidence coefficient measuring device for an artificial satellite according to claim 1, wherein the point-like pulsed light source is a flash lamp. (3) The point pulse light source is a plurality of pulse laser light sources that emit selected light dispersed within the sunlight spectrum, and the light beams emitted from the light sources are sequentially or simultaneously diffused by a diffusing optical system and a random phase plate. 2. A solar light incident coefficient measuring device for an artificial satellite according to claim 1, characterized in that the optical system is configured to irradiate the artificial satellite with an optical system that converts the beam into an expanded parallel light beam. (4) 1st. The solar incidence coefficient measuring device for an artificial satellite according to claim 1, comprising a periodic detector for detecting the output of the second photodetector.