JP3038810B2 - Observation spectrometer - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an observation spectrometer, and more particularly to spectroscopic observation of a spectrum of light in a range from ultraviolet to visible light radiated from the earth or the earth's atmosphere mounted on an artificial satellite. Observation spectrometer.

[Conventional technology]

2. Description of the Related Art Conventionally, an observation spectrometer for earth observation mounted on an artificial satellite of this type observes a spectrum from ultraviolet light to visible light (earth observation light) emitted from the earth or the earth's atmosphere. It is necessary to scan the earth in the north-south (S-N) and east-west (WE) directions.

Conventional observation spectrometers consist of an earth light sampling unit for introducing earth observation light, a spectroscope for spectrally dispersing the introduced earth observation light, and a single unit for detecting the spectrum-separated earth observation light and converting it into an electric signal. And a light receiving sensor of the element. In this observation spectrometer, in order to perform north-south and east-west scanning of the earth, a scanning mirror whose reflection surface changes according to the scanning direction is placed at any position between the earth lighting unit and the light receiving sensor. The spectroscope is rotated for scanning in the spectral direction.

The calibration of the reference level of the earth observation light is performed using sunlight, but the specific season, that is, the position of the sun and the earth, is almost the same direction with respect to the earth light sampling part of the observation spectrometer mounted on the satellite. In addition, calibration can be performed only in a season in which the incident angle of sunlight to the earth light collecting unit is almost 0 °.

[Problems to be solved by the invention]

The above-mentioned conventional observation spectrometer requires a mechanical mechanism for rotating a scanning mirror or a spectroscope for imaging the earth observation light, and thus requires a long time to take an optical image of the entire earth. In addition, the size and weight of the observation spectrometer became large, and it was difficult to adjust the alignment.

Furthermore, the reference level calibration of light can be performed only in a specific season, and the observation accuracy of light intensity is poor.

An object of the present invention is to provide a high-precision, lightweight observation spectrometer capable of performing global spectroscopic observation in a short time.

[Means for solving the problem]

An observation spectrometer according to one of the present invention is an observation spectrometer mounted on a spin-controlled geostationary satellite for spectrally observing the spectrum of earth observation light emitted from the earth or the earth atmosphere using sunlight as a calibration light source. An integrating sphere that emits the sunlight in a certain direction different from the incident angle, an earth light collecting unit that causes the earth observation light to enter at an angle different from the sunlight with respect to the spin axis of the geostationary satellite, A half mirror that irradiates the sunlight and the earth observation light incident from the terrestrial light collecting unit from orthogonal directions at different times from each other and emits the light in the same direction different from the incident direction, Of the earth observation light emitted from the half mirror, the earth observation light having a predetermined width in the east-west direction of the earth and a field of view in the north-south direction is passed, or A slit for passing a portion corresponding to a field of view of the Earth observation light of the sunlight that has exited from the mirror, the and Earth observation light and a spectroscope for spectral spectroscopy and reflects the solar light that has passed through the slit,
A two-dimensional array sensor that two-dimensionally images the earth observation light and the sunlight reflected by the spectroscope.

An observation spectrometer according to another aspect of the present invention is an observation spectrometer mounted on a three-axis control type geostationary satellite that performs spectral observation of the spectrum of earth observation light radiated from the earth or the earth atmosphere using sunlight as a calibration light source. In a spectrometer, a first scanning rotating mirror that receives the earth observation light emitted from the earth and scans the east-west direction of the earth, and an incident angle of the sunlight that enters at an angle different from the earth observation light And a second scanning rotating mirror that rotates in accordance with the direction and reflects the sunlight to the integrating sphere via a first folding mirror, and radiates the incident sunlight in a certain direction different from the incident angle. An integrating sphere, the earth observation light reflected by the first scanning rotating mirror and the second bending mirror, and the sunlight from the integrating sphere are incident in orthogonal directions, and are in the same direction different from the incident direction. Exit to A half mirror, and the earth observation light having a predetermined width in the east-west direction of the earth and a field of view in the entire north-south direction of the earth observation light out of the earth observation light emitted from the half mirror, or the sun emitted from the half mirror A slit that passes a portion of the light corresponding to the field of view of the earth observation light, a spectroscope that spectrally / reflects the earth observation light and the sunlight passing through the slit, and the light that is reflected by the spectroscope. A two-dimensional array sensor for two-dimensionally capturing the earth observation light and the sunlight.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

 FIG. 1 is a configuration diagram of a first embodiment according to the present invention.

The observation spectrometer 11 is mounted on a spin-controlled geostationary satellite. Then, the terrestrial light collecting unit 8 collects the earth observation light A radiated from the earth 10, the solar light collecting unit 9 collects sunlight for correcting the light intensity, and the solar light collecting unit 9 receives the light. An integrating sphere 1 that absorbs fluctuations in the incident angle of sunlight, and two optical signals that are incident at orthogonal angles, that is, the earth observation light A that is incident from the earth light sampling unit 8 and the sun that is incident from the integrating sphere 1 A half mirror 2 for reflecting or passing (emitting) the light d in the same direction, a lens system 3 for condensing two optical signals emitted from the half mirror 2, that is, the earth observation light I or the sunlight d, and a lens A slit 4 for extracting sunlight 4 in a fixed east-west (EW) direction and a total south-north direction of the earth 10 of the earth 10 of the earth 10 having passed through the system 3 or a corresponding field of view 2 Spectrum of two optical signals alternately A spectroscope 5, a lens system 6 for condensing the optical signal reflected by the spectroscope 5, a two-dimensional array sensor 7 for two-dimensionally capturing the optical signal passing through the lens system 6, converting the optical signal into an electric signal, and sequentially reading the electric signal. Contains.

Here, the integrating sphere 1 is a structure in which, for example, a diffusion paint that reflects light in a random direction is applied to the inner surface of a hollow sphere, and light entrance holes and radiation holes are provided at arbitrary positions. When light enters the entrance hole of the integrating sphere 1, the light is irregularly reflected and emitted from the radiation hole with a considerable amount of attenuation. Then, even if the incident angle of the light to the incident hole changes, a part of the incident light is necessarily emitted to the radiation hole. The half mirror 2 emits half energy of the incident light to the lens system 3. The lens system 3 puts the optical signal on the slit 4 and the lens system 6
Makes the two-dimensional array sensor 7 form an image of an optical signal. The slit 4 allows the earth observation light I (optical signal) emitted from a narrow area in the east-west direction of the earth 10 to pass through a gap provided in the slit 4. The spectroscope 5 spectrally separates the incident optical signal by wavelength. In this configuration, the two-dimensional array sensor 7 performs imaging for each spectral spectrum in the horizontal direction on the paper surface in FIG. 1, and performs north-south imaging of the earth 10 in the vertical direction on the paper surface in FIG. The two-dimensional array sensor 7 sequentially reads out the spectral observation results of the earth observation light A radiated from the imaged earth 10 and outputs it as an electric signal.

This observation spectrometer 11 rotates (spins) around the spin axis of a spin-controlled geostationary satellite that is parallel to the rotation axis (almost north-south direction) of the earth 10.
(Scan) in the east-west direction.

As has been made clear in the above description, observation spectroscopy of the entire earth can be performed during one spin or one scan of the spin-controlled geostationary satellite.

The reference level calibration of the light intensity by the sunlight is performed when the earth observation light A is not observed. As one method for this, there is a method in which the incident angle of the terrestrial light collecting unit 10 and the incident angle of the solar light collecting unit 9 are made different in the spin axis direction. As shown in FIG. 1, the earth light lighting unit 8 and the sunlight lighting unit 9
If the positions of the satellites are changed by 180 degrees, the time difference between the incidence of the earth observation light A and the incidence of the sunlight on the observation spectrometer 11 according to the spin of the geostationary satellite can be maximized. The vertical angle of incidence of the sunlight on the observation spectrometer 11 with respect to the plane of FIG. 1 fluctuates according to the season because the earth axis (north-south) of the earth 10 is inclined with respect to the orbital plane with respect to the sun. The integrating sphere 1 absorbs the fluctuation of the incident angle and always emits sunlight to the half mirror 2. The field of view of sunlight passing through the slit 4 is equivalent to the field of view of the earth observation light b passing through the slit 4.

 FIG. 2 is a block diagram of a second embodiment of the present invention.

The observation spectrometer 27 is mounted on a three-axis control type geostationary satellite. The earth observation light A emitted from the earth 10 is introduced into the earth light collecting unit 25 and is incident on the scanning rotating mirror 21. The scanning rotary mirror 21 scans the earth 10 in the east and west directions.
A mirror surface is attached to the earth 10 at a 45 ° angle to a rotation axis extending in a direction parallel to the 10 earth axes. By rotating the rotation axis of the scanning rotary mirror 21, the earth 10 is scanned in the east-west direction. The earth observation light A reflected by the scanning rotary mirror 21 is reflected by the bending mirror 23 and enters the half mirror 2. The sunlight d is incident on the scanning rotating mirror 22, and the sunlight d reflected by the scanning rotating mirror is
The light enters the integrating sphere 1 via the bending mirror 24. The sunlight radiated from the integrating sphere 1 is incident on the half mirror 22. The mirror surface of the scanning rotary mirror 22 is provided at an angle of 45 ° with respect to a rotation axis extending in a direction parallel to the earth axis of the earth 10 and at an angle different from the incident direction of the earth observation light A. It is mounted facing the part 26. Then, the rotation axis is scanned in accordance with the incident direction of sunlight. In order to perform the calibration with sunlight at a large rate, the aperture angle of the sunlight collecting unit 26 needs to be a large angle in the direction perpendicular to the plane of FIG. As shown in FIG. 2, when the arrangement of the earth light collecting unit 25 and the solar light collecting unit 26 is different by 180 degrees, the observation spectrometer 27 of the three-axis control type geostationary satellite rotates the earth light collecting unit 25 by itself. Although it is always directed to the earth 10, the sunlight collecting part 26 can inject sunlight into the sun once a day.

The earth observation light A or the sunlight D incident on the half mirror 2 is transmitted through the lens system 3, the slit 4, the spectroscope 5, and the lens system 6 having the same configuration as in the first embodiment.
And converted into an electric signal. The behavior of the optical signal after the half mirror 2 is the same as in the first embodiment, and the description is omitted. As described above, the observation spectrometer 27 mounted on the three-axis control type geostationary satellite can also calibrate the light reference level by sunlight with great frequency.

[Effect of the Invention] As described above, according to the present invention, mechanical scanning is not required for scanning the north and south directions of the earth, and light intensity calibration by sunlight can be performed with high frequency. . As a result, there is an effect that spectroscopic observation of the entire earth can be performed with high accuracy in a short time, and a lightweight observation spectrometer can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention, and FIG.
It is a lineblock diagram of an Example of a. 1 integrating sphere, 2 half mirror, 3, 6 lens system, 4 slit, 5 spectroscope, 7 two-dimensional array sensor, 8, 25 earth light sampling unit, 9 , 26… Sunlight collecting part, 10… Earth, 11,27 …… Observation spectrometer, 21,22… Scanning rotating mirror, 23,24… Bending mirror, I ~ C …… Earth observation light, D ……Sun light.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01J 3/00-3/52 G01N 21/25-21/39

Claims (3)

(57) [Claims] An observation spectrometer mounted on a spin control type geostationary satellite for spectroscopically observing the spectrum of earth observation light emitted from the earth or the earth atmosphere using sunlight as a calibration light source. An integrating sphere that radiates in a certain direction different from the incident angle, an earth light sampling unit that causes the earth observation light to enter at an angle different from the sunlight with respect to the spin axis of the geostationary satellite, and an sphere emitted from the integrating sphere. A half mirror, in which the sunlight and the earth observation light incident from the earth light collecting unit are incident at different times from orthogonal directions and are emitted in the same direction different from the incident direction, and emitted from the half mirror. Of the earth observation light, the earth observation light having a predetermined east-west width of the earth and a field of view in the north-south direction is passed or emitted from the half mirror. A slit that passes a portion of the sunlight that corresponds to the field of view of the earth observation light, a spectroscope that spectrally / reflects the earth observation light and the sunlight that have passed through the slit, and is reflected by the spectroscope. And a two-dimensional array sensor for two-dimensionally capturing the earth observation light and the sunlight. 2. A first lens system for forming an image of the earth observation light and the sunlight emitted from the half mirror on the slit, and the earth observation light and the sunlight reflected by the spectroscope. And a second lens system that forms an image on the two-dimensional array sensor. 3. An observation spectrometer mounted on a three-axis control type geostationary satellite for spectroscopically observing the spectrum of earth observation light radiated from the earth or the earth atmosphere using sunlight as a calibration light source. A first scanning rotating mirror that receives the earth observation light and scans the east-west direction of the earth, and rotates in accordance with the incident angle of the sunlight that enters at an angle different from that of the earth observation light; A second scanning rotating mirror for reflecting the light on the integrating sphere via a first folding mirror, an integrating sphere for emitting the incident sunlight in a fixed direction different from the incident angle, and the first scanning rotation. A half mirror that receives the earth observation light reflected by the mirror and the second bending mirror and the sunlight from the integrating sphere in an orthogonal direction and emits the light in the same direction different from the incident direction; The earth observation light having a predetermined width in the east-west direction of the earth and the field of view in the north-south direction among the earth observation lights emitted from the earth, or the earth observation light out of the sunlight emitted from the half mirror A slit that passes through a portion corresponding to a field of view of light, a spectroscope that spectrally reflects and reflects the earth observation light and the sunlight that have passed through the slit, and the earth observation light and the sun that are reflected by the spectroscope An observation spectrometer comprising: a two-dimensional array sensor for two-dimensionally capturing light.