Linear diode array
Encyclopedia
A Linear diode array is used for digitizing
x-ray
images. The LDA system consists of an array of photodiode
modules, The diodes are laminated with a scintillation
screen to create x-ray sensitive diodes. The scintillation screen converts the photon
energy emitted by the x-ray tube into visible light on the diodes. The diodes produce a voltage
when the light energy is received. This voltage is amplified, multiplexed
, and converted to a digital signal.
One of the unique characteristics of the LDA is that it has an excellent dynamic range. This means that it is capable of generating useful data when x-raying both very thick (tread) and thin (sidewall) sections of a tire
simultaneously. However, the human eye is capable of visualizing only a small fraction of the LDA’s full dynamic range. To compensate for the limitations of the human eye while still taking advantage of this feature of the LDA, a variety of selectable contrast and brightness enhancing tables are available.
Digitizing
Digitizing or digitization is the representation of an object, image, sound, document or a signal by a discrete set of its points or samples. The result is called digital representation or, more specifically, a digital image, for the object, and digital form, for the signal...
x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
images. The LDA system consists of an array of photodiode
Photodiode
A photodiode is a type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation.The common, traditional solar cell used to generateelectric solar power is a large area photodiode....
modules, The diodes are laminated with a scintillation
Scintillation (physics)
Scintillation is a flash of light produced in a transparent material by an ionization event. See scintillator and scintillation counter for practical applications.-Overview:...
screen to create x-ray sensitive diodes. The scintillation screen converts the photon
Photon
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
energy emitted by the x-ray tube into visible light on the diodes. The diodes produce a voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
when the light energy is received. This voltage is amplified, multiplexed
Multiplexer
In electronics, a multiplexer is a device that selects one of several analog or digital input signals and forwards the selected input into a single line. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output...
, and converted to a digital signal.
Use
One of the unique characteristics of the LDA is that it has an excellent dynamic range. This means that it is capable of generating useful data when x-raying both very thick (tread) and thin (sidewall) sections of a tire
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
simultaneously. However, the human eye is capable of visualizing only a small fraction of the LDA’s full dynamic range. To compensate for the limitations of the human eye while still taking advantage of this feature of the LDA, a variety of selectable contrast and brightness enhancing tables are available.