JPS5939174A - Picture acquiring device using flat mirror in spin type satellite - Google Patents

Abstract

PURPOSE:To attain easily a picture of objective in spin state, by obtaining an optical image of an objective located at the outside of a satellite on a screen of a camera in the spin satellite via a rotary flat mirror and a fixed flat mirror. CONSTITUTION:A rotation mechanism and control system 5 controls the rotary flat mirror 2 based on the spin rate data of the satellite main body detected with a sun sensor or the like so that the rotary flat mirror 2 is rotated in a half speed of the spin rate (omega) of the satellite main body 1 viewed from the inertia space and in opposite direction as the direction of rotation of the stellite main body 1. Thus, a still objective image is obtained on a mirror 3 fixed to the satellite 1. The mirror 3 leads the image to an optional position in the satellite, makes it incident to a two-dimensional image pickup device 4, allowing to attain the two-dimensional image of the objective in the spin satellite.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging device for obtaining an image of an object outside the satellite in a spin-type satellite.

The above-mentioned device (c) spins down the satellite to an extremely low spin or stops the satellite quasi-statically with respect to inertial space, and creates an image inside the satellite by imaging with secondary elements, etc. Conventionally, there has been a method of obtaining an image of a target object by scanning the target object with an imager on a satellite and processing it within the satellite or on the ground.

In the former method, when the Fi subject is dark and it is necessary to lengthen the exposure time, Wμ will be kept at an extremely low spin or stationary, but this may cause the satellite's attitude to become unstable. This has the disadvantage that distortion occurs in the acquired image.

In the latter method, a multi-axis processing circuit is required to obtain images from signals scanned inside the satellite, which inevitably increases weight. Also, when processing scan signals on the ground, computer processing is required, and the entire system is
1. There was a drawback that it became Mf.

In addition, in the scan type imaging method, since the imaging time for - times is determined by the scan rate, there is also a drawback that the sensitivity deteriorates when the target object is dark.

An object of the present invention is to provide an image acquisition device M'fe using a plane @ that can easily obtain an image of a target object within the satellite while maintaining the spin stability of the satellite.

In order to achieve the above object, an image acquisition device using a plane mirror in a spin-type satellite according to the present invention is installed on one end face of the spin-type satellite, and the rotation axis on the plane is set to be parallel to the rotation axis of the spin-type satellite. a rotating plane mirror provided on one end surface of the spinning satellite; a rotating plane mirror provided on one end surface of the spinning satellite; A rotation mechanism that rotates the spin satellite so that its rotation speed is 1/2 of the rotation speed of the spin satellite and its control system, and an optical image of a target object outside the satellite is transmitted between the rotating plane mirror and the fixed plane mirror. It is grooved so that it can be seen on the screen of a camera in a spinning satellite.

According to the above configuration, the spinning satellite can easily capture images of the target object in a spinning state, and the object of the present invention is completely achieved.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of an image acquisition device using a plane mirror according to the present invention, and is a plan view seen from the spin axis direction and a front view seen from the direction perpendicular to the spin 111.

In the figure, 1 is Mamoru's main body, 2 is a rotating plane mirror attached to Mamoru's IR parallel to its spin axis, 3 is a mirror fixed to the satellite, and 4 is
A two-dimensional imaging device such as an I/i two-dimensional CCD or an IDT, and 5 indicate a rotation mechanism and a control system, respectively. Based on the spin rate data of the satellite main body detected by the rotating machine tank and the control system 5Iri sun sensor, etc., the rotating plane mirror 2 is set at half the spin rate (ω) of the satellite main body 1 when viewed from inertial space, and the guard main body 1 The rotating plane mirror 2 is controlled so that it rotates in a direction opposite to the direction of rotation. This fixed it to the satellite @3
Is there a stationary target object image? FJ is done. Mirror 3 further guides this image to an arbitrary location within the satellite and displays it on a two-dimensional CCD+I
The light enters a two-dimensional imaging device 4 such as a DT. A two-dimensional image of the target object is obtained within the spinning satellite through the optical path described above. Here, it will be mathematically proven that a still image of the object can be obtained on the wing 3 by the above-described operation.

Since the property of mirror 3 to reflect a real image can be mathematically considered as a kind of coordinate transformation, the transformation matrix of the bell can be obtained as follows. Now, considering a rectangular coordinate system whose origin is an arbitrary point on the mirror surface, each vector is defined as shown in FIG.

N: Vector M in the plane of the mirror; Unit normal vector P of the mirror; Position vector t of the object; Position vector of the virtual image of the object due to the mirror Vector N,
Satisfies Mtill1 formula.

(NM)=o, IM+=1 −
--- B) Also, the position vector P of any object P
It is expressed by a vector equation of the H+21 formula.

P=tM×N (t: constant) ... (2)
Here, from equation (1), (MP)=t 1M12+(M・N)=t
Since (3), the substitution deviation of (31) into equation (2) is P = (M - P
)M0N...(4) Furthermore, from the geometrical properties of the bell, Kousumi fKarishihame=N-tM
...(5), and in equation (5), (
By substituting Equation 31 and Equation (4), we obtain Equation (6) as the vector equation of the virtual image.

d=p-2(M-P)M (6) Then, if it is, then the virtual image ys: From equation (6), it can be expressed as, and the mirror transformation ma) +7xM can be obtained.

However, as shown in Figure 1, when a mirror is mounted on a satellite, the virtual image of an object P that is stationary in inertial space is reflected in mirror 3.
Ask how it looks.

Figure 3 shows the coordinate system when rotating plane @2 is mounted on the satellite. However, it is assumed that K Z @ is in the plane of the rotating plane mirror 2, and the Z axis is parallel to the spin axis. Also, the rotating plane mirror 2 rotates around the Z axis at ω/2 when viewed from the satellite]2
, the satellite rotates at ω around Svinra 1 G-.

Now, GO=Y't, GP='l'2, op
If we set =p, then P=1'2n! l) ,? 2.2
1 If we look at &: in terms of the satellite fixed seat, where: rtrz: constant α; Since it can be set as the initial phase difference between the unit normal vector of the bell (M) and P, we can express P in the coordinate system 0. . Therefore, when observing celestial bodies from a satellite, IT* l >
ll' lI j From the satellite fixed system, equation (8) holds true.

Also, since it can be written as the unit normal vector M of the mirror seen from the satellite fixed system, the Nishiki conversion matrix material in this case is as follows from equation (7). Therefore, the virtual image of the object P seen from the satellite can be expressed by the +111 formula.

The virtual image f) of an object P seen from a satellite spinning at an angle of ω and through a mirror rotating at an angle of ω is independent of time tK, υ, which is obtained by the rotating plane mirror 2 in Fig. 1. This means that the image of the object P is stationary when viewed from the satellite.

As described in detail above, according to the present invention, it is possible to easily obtain an image of a target object within the satellite while keeping the entire spin of the satellite stable. In addition, in a spin-type satellite in which a wheel is mounted to obtain an image within the satellite, and the satellite is spun down or stationary during imaging, the use of the present invention has the advantage that the wheel can be eliminated. Also,
Since it is composed of a combination of simple optical systems, it is easier to handle than a scan type imaging system, and it also has the advantage that it is possible to use a two-dimensional CCD or the like as an image receiving device, reducing both the size and power consumption.

[Brief explanation of drawings]

FIG. 1 is a plan view and a front view showing an embodiment of an image acquisition @ apparatus using a plane mirror according to the present invention. Figure 2 is a diagram showing the coordinate system for determining the mirror transformation matrix, Figure 3 (
1 is a cost I star and 4. FIG. 3 is a diagram showing a coordinate system when a t. 1.--Satellite main body 2..One-rotation plane mirror 3..Fist fixed plane mirror 4.Fist.Two-dimensional imaging device 5.Me rotation mechanism and part 11: Introduction 11 series patent applicant NEC Co., Ltd. agent Patent attorney I ) Ro Hisashi Figure 1 Figure 3

Claims (1)

[Claims] a rotating plane mirror provided on one end surface of the spin satellite and set so that the rotation axis on the plane is parallel to the rotation axis of the spin satellite; a satellite fixed plane mirror for determining the elevation direction of imaging; A rotating plane mirror provided on one end face of the spin satellite is rotated in a direction opposite to the rotation direction of the spin satellite, and its rotation speed is 17 times higher than the rotation speed of the spin satellite.
2, and a control system for the rotation mechanism, to obtain an optical image of a target object outside the satellite onto a screen of a camera or the like inside the spinning satellite via the rotating plane mirror and the fixed plane mirror. An image acquisition device using a plane mirror on a spin-type satellite.