08-03-2013, 06:18 PM
require seminar notes on working principle of vidicon and digital camera
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seminar notes of vidicon and digital camera working principles ppt
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require seminar notes on working principle of vidicon and digital camera
24-10-2013, 06:13 AM
i need vidicon and digital camera working principle materials
16-02-2014, 06:34 PM
plz send me the latest technical seminar topics based on IT field
30-06-2015, 07:37 PM
01-07-2015, 04:06 PM
seminar notes of vidicon and digital camera working principles ppt
Television camera or video camera, the camera used in X-ray fluoroscopic and digital imaging for converting the dynamic optical image into a standard video signal. Because of the recent importance that digital X-ray imaging has assumed, the television camera has been significantly refined to provide improved image resolution, increased dynamic range, and improved temporal resolution over the cameras used in non-medical imaging applications. Colour video cameras are not used in medical X-ray imaging. Points of importance include the light sensor, the image scanner, and the scanning format.
Although many types of video cameras are available, the camera basically consists of a small electronic vacuum tube surrounded by coils (focusing coils, horizontal and vertical deflecting coils). The image receptor (target) is composed of a thin field of photoconductive material. In one of the most commonly used video cameras, the vidicon, the photoconductive material is usually antimony sulphide (Sb2S3) suspended as globules in a mica matrix. In a plumbicon, the material is lead monoxide (PbO). The target is mounted next to a conducting plate (the signal plate) which is in turn mounted on a glass face plate. Each globule is about 0.025 mm in diameter and is insulated from the neighbouring globules and from the signal plate by the mica matrix. The light from the image is focused through the glass plate, the signal plate and mica matrix onto the photoconducting globules, and photoelectrons are emitted in proportion to the intensity of light. These electrons are attracted to the anode and are immediately removed from the tube. The globules are capacitively coupled to the signal plate, and the residual positive charge on the globules causes current to flow onto the signal plate. After exposure and emission of the photoelectrons, a residual image that is an exact replica of the light image focused on the target is stored in the photoconductor as a positive charge distribution.
The stored image is read out by scanning an electron beam across the globules. The electron beam is emitted from the cathode, which is located at the opposite end of the camera tube from the target. The cathode is heated indirectly by an internal electric coil. This heating causes electrons to be emitted from the cathode by thermionic emission, creating an electron cloud. These electrons are formed into a beam by the control grid which begins the electron acceleration towards the target. This cathode/grid assembly is called an electron gun because it shoots the electrons out of the end of the control grid. The electrons are accelerated by a 250 V potential difference toward the anode, which consists of a fine wire mesh in front of the signal plate. The signal plate is at a lower potential than the anode, and the electrons are decelerated as they approach the plate, reaching a net energy of about 25 eV. This decelerating field also straightens the path of the electrons, causing them to strike perpendicularly to the signal plate.
The electron beam is focused to a fine point as it hits the target and is scanned over the target by the deflecting coils. The beam discharges each globule, discharging the capacitor and causing current to flow from the signal plate. This current equals the charge stored in the photoconductor. By scanning the electron beam across the entire surface of the photoconductor, the entire image can be detected. The output signal, the video signal, is a one-dimensional voltage versus time curve presentation of the two-dimensional image. The video signal is amplified and later used in the "reverse" process in a television monitor. In digital fluoroscopy DF systems, the signal can be digitized and transferred to a computer memory for appropriate processing of the image.
A vidicon tube is a video camera tube design in which the target material is a photoconductor. The Vidicon was developed in the 1950s at RCA by P. K. Weimer, S. V. Forgue and R. R. Goodrich as a simple alternative to the structurally and electrically complex Image Orthicon.While the initial photoconductor used was selenium, other targets-including silicon diode arrays-have been used. Schematic of vidicon tube.
The vidicon is a storage-type camera tube in which a charge-density pattern is formed by the imaged scene radiation on a photoconductive surface which is then scanned by a beam of low-velocity electrons. The fluctuating voltage coupled out to a video amplifier can be used to reproduce the scene being imaged. The electrical charge produced by an image will remain in the face plate until it is scanned or until the charge dissipates. Pyroelectric photocathodes can be used to produce a vidicon sensitive over a broad portion of the infrared spectrum.
Prior to the design and construction of the Galileo probe to Jupiter in the late 1970s to early 1980s, NASA used Vidicon cameras on most of their unmanned deep space probes equipped with the remote sensing ability
Television camera or video camera, the camera used in X-ray fluoroscopic and digital imaging for converting the dynamic optical image into a standard video signal. Because of the recent importance that digital X-ray imaging has assumed, the television camera has been significantly refined to provide improved image resolution, increased dynamic range, and improved temporal resolution over the cameras used in non-medical imaging applications. Colour video cameras are not used in medical X-ray imaging. Points of importance include the light sensor, the image scanner, and the scanning format.
Although many types of video cameras are available, the camera basically consists of a small electronic vacuum tube surrounded by coils (focusing coils, horizontal and vertical deflecting coils). The image receptor (target) is composed of a thin field of photoconductive material. In one of the most commonly used video cameras, the vidicon, the photoconductive material is usually antimony sulphide (Sb2S3) suspended as globules in a mica matrix. In a plumbicon, the material is lead monoxide (PbO). The target is mounted next to a conducting plate (the signal plate) which is in turn mounted on a glass face plate. Each globule is about 0.025 mm in diameter and is insulated from the neighbouring globules and from the signal plate by the mica matrix. The light from the image is focused through the glass plate, the signal plate and mica matrix onto the photoconducting globules, and photoelectrons are emitted in proportion to the intensity of light. These electrons are attracted to the anode and are immediately removed from the tube. The globules are capacitively coupled to the signal plate, and the residual positive charge on the globules causes current to flow onto the signal plate. After exposure and emission of the photoelectrons, a residual image that is an exact replica of the light image focused on the target is stored in the photoconductor as a positive charge distribution.
The stored image is read out by scanning an electron beam across the globules. The electron beam is emitted from the cathode, which is located at the opposite end of the camera tube from the target. The cathode is heated indirectly by an internal electric coil. This heating causes electrons to be emitted from the cathode by thermionic emission, creating an electron cloud. These electrons are formed into a beam by the control grid which begins the electron acceleration towards the target. This cathode/grid assembly is called an electron gun because it shoots the electrons out of the end of the control grid. The electrons are accelerated by a 250 V potential difference toward the anode, which consists of a fine wire mesh in front of the signal plate. The signal plate is at a lower potential than the anode, and the electrons are decelerated as they approach the plate, reaching a net energy of about 25 eV. This decelerating field also straightens the path of the electrons, causing them to strike perpendicularly to the signal plate.
The electron beam is focused to a fine point as it hits the target and is scanned over the target by the deflecting coils. The beam discharges each globule, discharging the capacitor and causing current to flow from the signal plate. This current equals the charge stored in the photoconductor. By scanning the electron beam across the entire surface of the photoconductor, the entire image can be detected. The output signal, the video signal, is a one-dimensional voltage versus time curve presentation of the two-dimensional image. The video signal is amplified and later used in the "reverse" process in a television monitor. In digital fluoroscopy DF systems, the signal can be digitized and transferred to a computer memory for appropriate processing of the image.
A vidicon tube is a video camera tube design in which the target material is a photoconductor. The Vidicon was developed in the 1950s at RCA by P. K. Weimer, S. V. Forgue and R. R. Goodrich as a simple alternative to the structurally and electrically complex Image Orthicon.While the initial photoconductor used was selenium, other targets-including silicon diode arrays-have been used. Schematic of vidicon tube.
The vidicon is a storage-type camera tube in which a charge-density pattern is formed by the imaged scene radiation on a photoconductive surface which is then scanned by a beam of low-velocity electrons. The fluctuating voltage coupled out to a video amplifier can be used to reproduce the scene being imaged. The electrical charge produced by an image will remain in the face plate until it is scanned or until the charge dissipates. Pyroelectric photocathodes can be used to produce a vidicon sensitive over a broad portion of the infrared spectrum.
Prior to the design and construction of the Galileo probe to Jupiter in the late 1970s to early 1980s, NASA used Vidicon cameras on most of their unmanned deep space probes equipped with the remote sensing ability
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