- Отрасли: Medical devices
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Manufacturer of medical devices and products, with particular focuses on treating hemophilia, immune disorders, infectious diseases, kidney disease etc.
Electronic pulsing of the laser driving circuit to produce a pulsed output (250-1000 times per second), with peak powers per pulse higher than the maximum attainable in the continuous wave mode. Average powers of superpulse are always lower than the maximum in continuous wave. Process often used on CO2 surgical lasers.
Starting from a continuous light source, the output power is constant. Regularly switching it on and off makes the output light pulsed. This can also be done by periodically block the light with a mechanical shutter. The duty cycle can be chosed between 100% and 0%. The most common value is 50%. Pulse frequency can be any. For high duty cycle values, the average outpu power is close to the output power of the non switched situation. When the duty cycle is 50%, the average output power is 50% of the non switched output power.
In pulsing in general it is not always possible that the light source can run in continuous mode. A good example of this one of the very first semiconductor lasers - the Gallium-Arsenide laser. In order to achieve lasing (inverse population), the current density in the crystal had to be in the order of 10,000 amperes per square centimeter. This causes, however a very high temperature raise which could only be handled by using a very low duty cycle, typically in the order of 0.1%. The advantage was that the momentary peak power could be made very high. Typical values of these parameters in todays applications is 100 - 200 ns pulse duration and peak power of 1 to 1000 watts and pulse repetition rates of 1- 100 kHz. The wavelength is typically 904, 905 or 890 nm. This semiconductor laser is today primarily used in therapeutic laser devices (LLLT, Low Level Laser Therapy) and in speed measuring cameras. Energy content of each pulse is relatively low, often in the order of micro joules.
Finally, a similar type of extreme pulsing is q-switching when both peak power and pulse energy can be very high, but with low pulse repetion rate. Q-switched lasers are today often used in bleaching of tattoo pigment in skin. Typical values can be pulse duration 100 ps, 100 - 10,000 megawatts in peakpower and pulse repetition rates of 1 to 10 Hz.
Industry:Medical devices
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