JP3132088B2 - Scanning radiometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning radiometer which optically scans an object to be imaged and performs imaging.

[0002]

2. Description of the Related Art As is well known, a scanning radiometer scans an object to be imaged with a scanning mirror to acquire imaging light, condenses the light with an optical system, and stops the aperture at a focal position of the optical system. This is a device that forms an appropriate amount of light on the detector, forms an image on the detector, and performs signal processing on the output signal of the detector to obtain an image of the object to be imaged. When installed on the ground, flying objects such as artificial satellites and aircraft In some cases.

[0003] The spatial resolution of a scanning radiometer is determined by the instantaneous visual field (the ratio of the focal length of the optical system to the aperture of the detector (ie, the size of the aperture)) and the distance from the radiometer to the object to be imaged. The distance is defined by a distance, which is conventionally fixed.

[0004]

As described above, since the conventional scanning radiometer has a fixed spatial resolution, there is little trouble when installed on the ground. When mounted and used for observation of the ground surface, if the spatial resolution is fixed, it is difficult to perform observations according to ground surface conditions, such as performing coarse observations to some extent and performing fine observations in the event of a disaster, for example. There is.

An object of the present invention is to provide a variable resolution scanning radiometer capable of automatically variably setting a spatial resolution.

[0006]

To achieve the above object, a scanning radiometer according to the present invention has the following configuration. That is, a scanning radiometer of the present invention includes: a scanning mirror for scanning an object to be imaged; an optical system for condensing imaging light from the scanning mirror; A scanning radiometer comprising: a signal processing unit that processes an output signal of the detector; and a variable aperture mechanism that has a variable aperture size and changes the size of the aperture. ; a provided, said means for controlling the variable aperture mechanism to the signal processing section; the provided, the
It is possible to automatically change the spatial resolution during scanning of the imaging object
It is characterized by having done.

[0007]

Next, the operation of the scanning radiometer according to the present invention will be described. The spatial resolution of a scanning radiometer is defined by the instantaneous field of view and the distance from the radiometer to the object to be imaged. The instantaneous field of view is determined by the ratio between the focal length of the optical system and the size of the aperture. Therefore, in the present invention, the aperture is a variable aperture type, the size of the aperture is changed by a variable aperture mechanism operated under the control of the signal processing unit, the instantaneous visual field is changed, and the spatial resolution is automatically varied. .

As a result, when the scanning radiometer of the present invention is mounted on an artificial satellite or the like and used for observing the ground surface, the observation is usually made at a somewhat coarse resolution, and when a disaster such as a fire or earthquake occurs, the observation is made at a fine resolution. Observations can be made according to the surface conditions.

[0009]

FIG. 1 shows a scanning radiometer according to an embodiment of the present invention. In FIG. 1, a scanning mirror 1 scans an object to be imaged (not shown). The imaging light 2 acquired by the scanning mirror 1 is condensed by an optical system 3 and forms an image on a detector 4 disposed at a focal position.

At this time, a stop aperture 5 is provided on the front surface of the detector 4, that is, at the focal position, so that the light enters the detector 4 with an appropriate amount of light. The opening 5 has a variable opening size a and a variable opening mechanism 6 for changing the size of the opening.

The signal processing unit 7 performs signal processing on the output signal of the detector 4 to output a video signal of the object to be imaged. In the present invention, the signal processing unit 7 controls the variable aperture mechanism 6 to control the aperture 5
Means for setting the aperture size a of a to an appropriate value between a = 0 and a = d (d is the diameter of the light receiving surface of the detector 4 in the illustrated example) is provided, and the value of a, that is, the value of the spatial resolution is provided. In accordance with the above.

That is, the spatial resolution of the scanning radiometer is defined by the instantaneous field of view and the distance from the radiometer to the object to be imaged. The instantaneous field of view is determined by the focal length f of the optical system 3 and the size of the aperture 5. This is the ratio (a / f) to a. Therefore, in the illustrated example, since the aperture 5 is provided on the front surface of the detector 4,
As shown in FIG. 2A, the maximum value of the aperture size a of the stop aperture 5 is restricted by the diameter d of the light receiving surface of the detector 4, but the value of the aperture size a is one pair with the value of the spatial resolution. Corresponds to 1.

Therefore, the signal processing section 7 reduces the aperture 5 when increasing the spatial resolution, widens the signal band and shortens the sampling period while increasing the spatial resolution, and reduces the aperture 5 when decreasing the spatial resolution. Together with
The signal processing according to the resolution, such as narrowing the signal band and lengthening the sampling cycle, or performing the extraction (averaging) processing using the same short sampling cycle as in the case of the high resolution, is performed by a preset program. According to
Alternatively, it is executed in response to an external command.

As shown in FIG. 3, when the optical system 3 is composed of a condenser system 3a and a relay system 3b, the focal position is located between the condenser system 3a and the relay system 3b. Therefore, the aperture 5 and the variable aperture mechanism 6 are connected to the optical system 3 as shown in FIG.
The operation is the same as described above.

[0015]

As described above, according to the scanning radiometer of the present invention, the aperture is of a variable aperture type, and the size of the aperture is changed by the variable aperture mechanism operated under the control of the signal processing unit. Since the instantaneous field of view can be changed and the spatial resolution can be automatically varied, when the scanning radiometer of the present invention is mounted on an artificial satellite or the like and used for observing the ground surface, the observation is usually performed with a somewhat coarse resolution. For example, when a disaster such as a fire or an earthquake occurs, there is an effect that observation according to the condition of the ground surface, such as observation with a fine resolution, can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a scanning radiometer according to an embodiment of the present invention.

2A and 2B are diagrams showing the relationship between a detector and an aperture in the scanning radiometer shown in FIG. 1; FIG. 2A shows a case where the aperture size is the same as the light receiving surface of the detector; This shows a case where the aperture size is smaller than the size of the light receiving surface of the detector.

FIG. 3 is a configuration diagram of a scanning radiometer according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scanning mirror 2 Imaging light 3 Optical system 3a Condensing system 3b Relay system 4 Detector 5 Aperture aperture 6 Variable aperture mechanism 7 Signal processing unit

Claims (1)

(57) [Claims] A scanning mirror for scanning an object to be imaged;
An optical system that collects imaging light from the scanning mirror; a detector that receives the imaging light from the optical system through a stop aperture and converts it electrically; a signal processing unit that processes an output signal of the detector;
Means for controlling the variable aperture mechanism in the signal processing unit; provided with a scanning radiometer comprising: a variable aperture mechanism having a variable aperture size and changing the aperture size; Is provided , and the
A scanning radiometer characterized in that the spatial resolution in scanning can be automatically varied .