Pulsed Wave, CW or Super Pulsed Laser, which is better?
Class 4 Lasers vs SuperPulsed Lasers and Cold Lasers – How do you choose?
Cold Lasers and Class IV Lasers emit light via laser diodes in three primary methods:
- Continuous Wave (CW)
- Pulsed Wave (PW)
- Super Pulsed Wave (SPW)
Continuous wave therapy lasers emit a beam of light that is uninterrupted and constant.
Pulsed wave therapy lasers cycle on and off in different ways and at different rates.
Super pulsed laser waves come from semiconductor laser diodes that typically only emit light pulses at 1,000th of a second, meaning its duty cycle is around 0.001% and average delivered power for a 25W super pulsed laser would be just 7-12mW.
Class 4 Lasers are most commonly available with laser diodes that can deliver CW or PW but do not offer super pulsing. CW lasers deliver the most therapeutic laser power to the target tissue than any other method, however the speed of delivery is dictated by the power of the laser diodes (measured in milliwatts (mW) and Watts (W). There are 1000mW in 1 Watt. Higher powered Class 4 lasers offer high speed photon delivery to target tissue, which makes it possible for busy therapists to effectively treat challenging musculoskeletal and soft tissue injuries within minutes. The higher the power in Watts, the faster the laser works. However, many practitioners like the therapeutic benefits that can be achieved from the addition of Hz frequencies. Utilizing these pulsed waves can double treatment times but offer additional frequency medicine benefits. Thus a 3 minute treatment with CW could be increased to a 6 min treatment with PW at 50% duty cycle:
- Class 4 Lasers – Choose from Over 20 Models of the best, most power and cost effective, FDA 510k Class 4 lasers that are on the market today.
All pulsed wave therapy lasers cycle on and off while operating – this cycle is called a “pulse”. However, the length of time that the laser is emitting light and turned off during each pulse varies between lasers. We can understand the length and frequency of a pulsed wave laser’s on and off cycles using the following parameters:
Pulse Duration (PD)
The amount of time, in seconds, that the laser is emitting light during each pulse.
Pulse Interval (PI)
The amount of time, in seconds, that the laser is off (not emitting light) during each pulse.
Pulse Frequency Rate (PFR)
The number of pulses (on and off cycles) that a pulsed wave laser goes through each second. This parameter is measured in hertz. Keep in mind that hertz are equivalent to cycles per second – so a laser with a PFR of 7Hz is emitting 7 pulses per second.
Duty Cycle (DC)
The Duty Cycle (DC) is the pulse duration (PD) multiplied by the Pulse Frequency Rate (PFR). A duty cycle is expressed as a percentage or a fraction and can be determined with the equation DC = PFR X PD
Duty Cycle Equation:
DC = PFR X PD
The duty cycle tells us the percentage of time that a pulsed wave laser is emitting light while operating. However, the duty cycle does not tell us the power output that a pulsed wave therapy laser is emitting while operating.
For example, a pulsed wave laser with a duty cycle of 50% (or ½) is emitting light only half of the time while in operation.
The maximum power output, in watts, that a laser diode is capable of emitting
Average Power – this is the true telling variable that has many people confused.
The average power output, in watts, that a laser diode is capable of emitting over time.
It’s important to identify the average power output of a pulsed wave therapy laser because laser therapy dosage is based on energy density.
This means that when a clinician keeps track of the Joules/cm2 being delivered to a patient, they account only for the average power output – not the peak power.
Average Power Equation:
Average Power = Peak Power x PFR x PD
Identifying the average power output of a pulsed wave therapy laser allows us to determine the energy density of a dosage delivered to a patient.
Hz Pulsed Therapy Lasers vs Super Pulsed Therapy Lasers
Pulsed wave therapy lasers are either:
- Chopped or
- Super Pulsed – with SP lasers the peak power can be quite high, rivaling the best class 4 lasers, however, the pulses are at a mere billionth of a second, which results in an average power output that is drastically low, typically averaging in the 5-50mW range at best. This is the reason that SP lasers never utilize standard laser protocols that requirements in joules/cm2.
A chopped pulse wave therapy laser is essentially a continuous wave therapy laser that uses a pulse generator to turn it on and off at programmed intervals.
This is different than Super Pulsed lasers, which use semiconductor laser diodes. A semiconductor diode creates a high-wattage output for a very short duration followed by an extremely long cool-down period.
A Super Pulsed laser diode will typically emit light for about 1,000th of the time it is in operation, meaning its duty cycle is around 0.001%. This is why they utilize much higher powered laser diodes or they wouldn’t work in comparison to the most common types of Cold Lasers that range in power from 5mW to 500mW and sometimes when they bundle multiple diodes they get up to 2400mW (2.4 Watts).
There is a significant difference of price between Class 4 Lasers and Super Pulsed Lasers which are often considered Class II. Class 3b Cold Lasers are Typically Use Near InfraRed (NIR) Laser diodes and Produce a maximum power output of 500mW per diode and up to 750mW if
Some brands of class III therapy lasers use a superpulsed gallium arsenide (GaAs) laser diode with a peak power output of 25-watts. While that may sound impressive, keep in mind that this GaAs superpulsed laser diode is only capable of emitting 25-watts of power in brief, 200-nanosecond bursts, with a duty cycle of 0.001% – resulting in an average power output of less than 25mw (0.25-watts).
Understanding the difference between peak power output and average power output is key when reviewing pulsed wave therapy lasers. Many manufacturers like to boast about the high-wattage peak power outputs of their Super Pulsed laser diodes without being upfront about the average power outputs of their devices. Don’t be fooled into thinking that a 25-watt Super Pulsed laser can deliver therapeutic results that are comparable to those you will see from a 25 Watt continuous wave therapy laser. There is a reason that the Super Pulsed Lasers are significantly less expensive that Class 4 Lasers. When a person invests in a therapeutic laser they have to weigh the pros and cons including the typical duration of treatment, which determines how much laser therapy you can deliver in a given amount of time. That said, if you want the fastest high quality treatment every time, then investing in a powerful class 4 laser with the most power you can afford up to 45 Watts is key. Any more than that is not necessary, nor desirable since psychologically if a laser works too fast it becomes hard to believe.
If you have significantly more time to use the laser or you want it just for home use or you simply can not scrape the money together for a class 4 laser, then a higher powered Class 3b CW & PW laser or a Class II Light Therapy Device such as the LZR UltraBright 10-20 Watt could be a good choice. The good ones do produce high quality clinical results with the delivery of a sufficient dose of photonic energy, which is measured in joules per cm squared (j/cm2). We are happy to help you to get a laser light therapy device that will meet your needs and budget.
You can get the individualized support that you need by calling a laser specialist for Complimentary Concierge Service and Support at Discover Lasers LLC.
USING THE LINKS BELOW YOU CAN SEE AND LEARN ABOUT THE ABOVE 3 TYPES OF LASERS: