The purpose of this article is to look at low level lasers up to 100 mW peak or average power within the lower end of the price range. LEDs seem to help with a lot of things but for deeper set problems a high peak power may be required, and this necessitates pulsing. There are a number of high end systems costing thousands of dollars, but are there lasers with similar parameters for a fraction of the cost?
Low Level Laser Therapy Specifications
There are a huge number of devices and systems on the market now but most of these devices do not state all relevant parameters and so it is impossible to assess them. Suppliers rarely answer enquiries and sellers rarely understand what they’re selling or the questions being asked. I’ve come up with only a handful of devices/makers producing potentially viable devices under 2,000 USD. There may be some that I have missed entirely and others that may be viable but do not make their specifications available. I’ll take a look at some constant wave low powered lasers and some pulsed lasers with high peak power but low average power, but first let me explain the reasons for these power considerations.
Guidelines For Laser Treatment of Musculoskeletal Disorders
Take the example of musculoskeletal disorders, where penetration depth may be important. The World Association for Laser Therapy (WALT) presents guidelines for low level laser treatment of musculoskeletal disorders. If we look at these recommendation for achilles tendon they list a maximum power of 100 mW/cm2 but they also list Peak pulse output >1 Watt [*]. This means that the laser should be pulsed with a peak output above 1 Watt (1,000mW). Watts and mW (milliwatts) are measures of the power of the light source. The greater the mW or Watt output the greater the penetration of the light through the body (all other things being equal). So, with some conditions, depth of penetration and therefore power is important.
Heat & Pulsing
Heat is a factor that we seek to avoid with LLLT, but increased power increases the likelihood of heating tissues, which can limit therapeutic effect or cause damage. This is the main reason for pulsing. By switching the laser on and off rapidly (pulsing) we can use higher peak power to penetrate greater depth while allowing “off” periods to dissipate heat.
Duty cycle and work cycle are terms used to describe the percentage of time that the laser is in the “on” mode when pulsing. So if a laser has a peak power of 2 Watts and a work cycle of 1% then the average power will be 20mW. (2 Watts is 2,000mW divided by 100 is 20). Often when you see low figures cited in a study which may need require deep penetration it is the average power which is quoted and not the peak power.
Reporting – Peak Or Average Power?
In my previous article on LLLT for shoulder pain [*] I noted a review which listed a treatment as using a 3mW laser. When tracing through the primary sources I found that the peak output was actually 10,000mW. The study reported using a 904 nm wavelength laser with 4.000 Hz frequency with 180 nanosecond pulses with a peak power output 10 W. The average power was 3 mW [*]. It seems extremely unlikely that a constant wave (not pulsed) 3mW beam would have the same effect as a beam with 10,000mw peak power. Unless clearly stated it might be better to read power statements as average and not peak power. This article gives a good overview of pulsing [*]. This paper gives an example of why pulsing may be required [*]. Testing different laser parameters, multiple power and energy densities, only the high powered constant wave beam caused neurological and tissue damage to the animals.
Continuous Wave Laser
There are many other claims and theories about pulsing benefits which are not the topic of this article but may be worth investigating. Generally is seems that non-pulsed (CW) lasers from 10-50mW, perhaps up to 100 mW may be useful in treating conditions where depth/power are not a factor. These devices are suitable for quite a lot of treatments. I had seen many laser devices with these type of specs listed but none which listed the specs specifically as optical output, which is what matters. So it was unclear what the mW rating was referring to (input or output). Sellers usually don’t respond or don’t give satisfactory answers. Recently, someone pointed out an ebay seller claiming to test output of lasers.
Laserland store has a few dozen non pulsed lasers with power specifications and a number of these fall into the 10-100 mW power range and red/near-infrared wavelengths. I was told that the 650nm 100mW cross laser module was effective for chronic back pain. 100 seconds per point using some pressure, about a 10J dose at the surface. A Joule is the measure of energy dose used in LLLT/PBMT. 100 (seconds) x 100(mW) = 10,000 millijoule (10 Joules).
They have a number of other interesting lasers:
- 50mW red 650nm cross laser
- 50mW focusable red 650nm dot laser
- 100mW focusable red 650nm dot laser
- 100mW focusable near infrared 808nm laser
- 50mW focusable near infrared 980nm cross laser
There are a range of other lasers either outside of the 10-100mW range or needing separate power supply listed on Laserland. I contacted Laserland store to enquire about their laser power testing equipment but they have not responded. These devices are interesting if they are as listed but the risk is that they are not as listed.
Next up is the B-Cure laser. I’ve mentioned this one before. B-Cure produce a number of handheld devices which are all based around pulsed infrared 810 nm, 250 mW peak power laser. There are different versions which have slightly different pulse rates, pulse durations and work/duty cycles. I suspect these small differences are irrelevant for most uses. The 250mW peak power will allow for deeper penetration than the non pulsed lasers above and the pulsing will decrease or eliminate the risk of heat damage. It is still a relatively low peak power but probably strong enough for most treatments, perhaps excluding thick bone and the brain.
The work cycle is 30% meaning that reaching a dose of 4-8J as per WALT recommendations for most musculoskeletal disorders will take a little over one or two minutes (per point). The B-Cure laser is somewhat unique in that it has a beam which covers a particularly large area of 4.5 cm2 (1 cm x 4.5 cm). The average power is 75mW (30% of 250mW), relatively high but still within WALT recommendations for musculoskeletal disorders.
B-Cure Classic, which is the cheapest device in the range, is available on Ebay and Amazon.co.uk. The B-Cure Vet and B-Cure Sport Pro are listed on Amazon.com. I have listed the different specifications for the versions of B-Cure in this article [*].
B-CURE Laser Classic
- Laser Pulse frequency: 15 kHz
- Laser Pulse duration: 17 µS
- Energy per minute: 3.75 J (Joules)
- Work Cycle 30%
Handy Cure s’
Next up a little more power. There are a number of devices listed as manufactured by Terraquant. Some desktop terraquant devices list 2 x 25,000mW peak power at 904nm (near infrared). This device sells on eBay for about $6500 [*]. The average power is not listed on amazon but a few pages list an average power of 7.5mW, 1/10th of the B-Cure. Terraquant also make handheld devices with a 15,000mW peak pulse, same wavelength of 904nm for around 2500 USD [*].
I could not find an average power listing for handheld Terraquant devices. It seems that there are other devices with otherwise identical specifications being sold at much lower prices though. The Handy Cure s’ is listed in a few places with similar or identical specs to the Terraquant Solo handheld devices but the average power is listed for the Handy Cure s’ – up to 6.25mW – not far off the 7.5mW listed for the table top setup. The Handy Cure s’ sells for about 460 USD on ebay [*]. I suspect it’s similar to the 2500 USD game day laser [*].
The 25,000mw peak power makes the Handy Cure s’ hard to beat at the price, certainly for a production low level laser treatment product. A drawback is the low average power. At its maximum output it would take about 10 minutes to deliver 4 Joules to the surface, far longer than the B-cure, but the energy delivered to deeper tissues will be significantly higher, so the usefulness of each may depend on the treatment context, depth. Handy Cure s’ claims penetration up to 15 cm. It seems a better option than the B-cure up for deeper problems, even if the application times end up being significantly longer.
Magnetic Field &Pulsed LED
All of the Terra Quant and Handy Cure lasers also emit pulsed LED light and produce a static magnetic field. A number of claims are made about Terraquant/Handy Cure devices regarding biological interactions between the magnetic field and pulsed lasers. The only evidence I have found is a study with bacteria using a device similar to the Handy Cure s’ (average power range was lower, 0.4-1.4 mW vs 0,4 – 6,25 mW). [*] I don’t know anything about the effects of static magnets or how the results of that study could play out in the real world but it seems at least that the static magnet is safe.
- Static magnets for pain [*]
- Static magnets used worldwide for pain [*]
- Interaction of static and extremely low frequency electric and magnetic fields with living systems: Health effects and research needs [*]
- Safety of Strong, Static Magnetic Fields [*]
Finally we have Hedlab, the online store of E.Engin Hukum. I first came across mentions of Hedlab in some forum posts. After reading some positive reviews of devices used for tennis elbow I found the Hedlab eBay store. These are handmade constant and/or super pulsed lasers. Engin offers to make devices to specification and has a number of devices for sale on the ebay store.
Some of these devices have a very high peak power output, currently there are devices listed with up to 60 W per module. The higher powered devices have an average power of about 1/1000th of the peak power – so 60mW for the 60W modules, a duty cycle of 0.1% (see individual specifications). These devices will penetrate quite deeply and the treatment time will be reasonably short.
I contacted Hedlab to enquire about his methods of power rating the laser output. Engin uses 3 different laser power meters. IL1400A (International Light inc) with SPL024F probe for testing low peak power lasers and two different Ophir brand laser power meters for high power laser. You can see that these brands and models are used in experiments to verify and calibrate laser power, for example, [*]. Hedlab devices are produced within the range of manufacturer specifications for each part. Let’s take a look at some of the listings.
This is a 2x 80mW constant wave device. One laser is red 650 nm and the other is near infrared 780 nm. This device pulses at 2500 Hz but rather than simple on/off it cycles between the two lasers, so one is always in the on state when both lasers are switched on. It was one of these devices I first saw mentioned for treatment of tennis elbow [*].
Hedlabs also lists a laser with three of these dual pulsed systems in one unit. This is similar to the previous design but covers three spots simultaneously. Generally treatments require 3-8 spots to be treated in a session so this device would likely cut down treatment time.
This is 20 W peak power, less than or equal to 20mW avg power, 850nm infrared laser. The penetration might be similar to the Handy Cure s’ due to similar wavelength and peak power but the average power for this device is more than 3x higher, so it would take much less time to apply the same energy dose (Joules) to the surface.
This is a Super Pulsed laser with 60 W peak power, average power less than or equal to 60 mw, 905nm near infrared. Engin believes that these higher powered devices could penetrate up to 6 inches. These are quite small and light devices compared to others.
There is also a version listed with 4 of these 60W 905nm super pulsed modules that run at the same time, allowing for faster treatment of multiple spots. The higher powered lasers have very high pulse rates, up to 30,000hz.
Hedlab can also produce laser modules and diodes with different specifications in the same device. Though all of the devices listed on this page are interesting to me I decided to go with Hedlabs because of the specifications he offers and because of the information supplied regarding how the lasers are rated for power. Being able to get multiple laser types (power/wavelength/pulsing/constant) in one unit seems will be useful to help understand the different qualities of lasers in the real world. I’ll post some more on the Hedlab device when it arrives. I believe this is Engins blog, chrome can translate in browser if you do not read Turkish [*].
*Handy Cure s’ and B-Cure suppliers claim to have approval for use in the US and EU. Neither Laserland nor Hedlabs make these claims and I cannot recommend them for human use. This is for comparison purposes only. Please do your own research.*