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Picoseconds are a measure of time used in technology like lasers and microprocessors. Personal computers are approaching picosecond speeds, while supercomputers in the US and China already exceed it. Picosecond lasers emit light pulses, and there are different designs that can operate at these speeds. In nuclear medicine, PET machines construct images at optimal rates of about 170 picoseconds, but reconstructing an image is a slow process.
A picosecond is one trillionth of a second. It’s a measure of time that comes into play with types of technology like lasers, microprocessors, and other electronic components that run at extremely high speeds. Nuclear physics research also includes measurements approaching the picosecond range, as well as imaging related to nuclear medicine using positron emission tomography (PET).
Personal computers are gradually approaching the speed where a single calculation can be performed in a picosecond. A home computer with a microprocessor operating at three gigahertz executes three billion cycles per second. This means that it actually takes about 330 picoseconds to perform a single binary operation.
Supercomputers in the United States and China already exceed the speed of one picosecond per operation. One of the fastest supercomputers in the United States can perform 360 trillion operations per second, slightly faster than one operation per picosecond. China revealed a supercomputer in 2010 capable of performing 2.5 petaflops per second, or 2.5 quadrillion operations per second, meaning that each picosecond optimally performs 2,500 calculations.
Lasers designed to operate in the picosecond range emit light pulses every one up to several tens of picoseconds over time. There are several types of laser designs that can operate at these speeds, including bulk solid-state lasers, mode-locked fiber lasers, and Q-switched lasers. Each model is built on the picosecond diode, which can be mode-locked or gain-switched, changing the pulse rate from nanosecond speeds that are in billionths of a second, to at least ten times faster in the 100 picosecond range.
While such ultrafast lasers are hard to imagine, there is an even faster level of models. A picosecond pulsed laser is 1,000 times slower than a femtosecond laser. This makes picosecond designs less cutting edge and significantly cheaper for uses such as component micromachining. Both types of lasers have similar levels of performance for the jobs they are entrusted with.
In the field of nuclear medicine, a PET machine constructs an image through gamma rays that interact with sparkling crystals to produce Compton electrons at optimal rates of about 170 picoseconds. In reality, this is usually much slower, requiring 1 to 2 nanoseconds in length per emission particle. PET time-of-flight research (TOFPET) is attempting to reduce effective time-of-flight to less than 300 picoseconds, through improvements in photodetectors, the sparkling crystals themselves, and associated electronics. While these speeds are already incredibly high, reconstructing an image of regions of the human body from these emissions is a slow and time-consuming process that often takes several days to complete.
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