Device for remote detection of radiation sources.
Patent 2706626 France, IPC G 01 T 1/16 .- Published 23.12.94.
Device for remote detection of radiation sources.
The subject of the invention is a device for remote detection of radiation sources, in particular gamma radiation. An important application of this invention may be the survey of areas of radioactive contamination. Several patent applications and patents are known in which such a detection device is proposed (for example, FR-A-2, 575821, EP-A-0188973 and USA-4797701).
To detect radiation sources, this device uses a pinhole camera, in which a film sensitive to the expected radiation and a film sensitive to visible light in the area where the radiation source may be located are placed.
The shutter of the camera, which allows taking pictures in visible light, is transparent to the radiation of the source. After developing the exposed films and combining them, the presence of the radiation source can be detected. The disadvantage of this device is the relatively long exposure time.
This invention aims to eliminate this disadvantage, i.e. reduce the exposure time. The camera obscura used in the device is enclosed in a specially shaped housing with a front and back wall and shielding the camera from the radiation of the detected source.
The device body is made of a special tungsten alloy, the high density of which significantly weakens the radiation of the source. The camera has a collimator that forms a radiation beam in the form of a cylindrical cone falling on its diaphragm. An X-ray luminescent screen is inserted into it through an opening in the back wall of the body, installed behind the camera, on which a hidden image of the radiation source is formed. After installing the screen, the opening in the back wall of the body is closed with a plug, and the screen is fixed in a given position with a leaf spring.
A video camera is attached to the device body, transmitting images of the area being examined in the form of electrical signals. The optical instruments of the device are adjusted so that the video camera transmits the same image that is formed on the X-ray luminescent screen by the pinhole camera. The video camera signals are sent to the analog-to-digital conversion and storage unit, and the latent image from the screen is read by a special circuit, the signals from which are also sent to its own analog-to-digital conversion and storage unit.
The digital image signals from these two units are transmitted to the next common image superposition and alignment unit. A video monitor or printer is used to visualize the image signals. The reproduced and aligned images make it possible to determine the location of radiation sources in the area.
The procedure for using the radiation source detection device is as follows: after selecting the examination area, the X-ray luminescent screen of the pinhole camera is placed in the device body and the video camera is oriented to film this area. The video image signals and the latent image on the screen are processed as described above. The device, which is the subject of this invention, can also be used for mapping areas of radioactive contamination. For this purpose, it must be installed on an appropriate carrier (airplane, helicopter).