One thing is for sure Sean. You are a genius. I don't know if I will
every completely understand what you have so eloquently said but I
now know there is more to lasers than just nm and mw. So I need to
find something affordable that works. Perhaps I can build my own
laser system or have someone build one for me that understands all of
this. My quest continues. Thanks for the great info.

Blessings
Steve

--- In Therapeutic-Laser_Therapy@yahoogroups.com, "Sean Tume"
<seantume@...> wrote:
>
> Hi Jennifer, Steve and everyone,
>
> I thought I would try and help with the line vs dot question with
some of
> the equations as to how this is worked out being the output power,
while
> important is not the only parameter we need to be aware of. Firstly
however,
> to simply answer your question.... If a laser manufacturer is using
a 5mW
> diode which is situated at the very tip of the laser probe using a
lens
> configuration, you will automatically lose (depending on the lens)
up to 10%
> of the power through the lens so you could be essentially starting
with a
> 4.5mW output power. Secondly, over time the diode will age (most
diodes
> have an approximate 10,000 hour life span so depending on how much
you use
> your laser you will lose output power over the life of the diode.
This is
> one reason why it is a good idea to get your laser tested regularly.
> Lastly, some manufacturers will use a limiting resistor on the
diode to
> reduce the output power and prolong the life of the diode
(basically a
> diodes output is based on the current it receives ie: max current =
max
> output, reduced current = reduced output) . For example, a
manufacturer may
> start with a 5mW diode but limit it to say 3mW with an appropriate
resistor
> hence running the diode at 60% of its max output and considerable
> lengthening the life of the diode. However, in this example you are
now
> starting with a 3mW diode and allowing for up to 10% loss through
the lense
> you are actually receiving a 2.7mW laser at point of sale which
will reduce
> over time as the diode ages. Therefore, yes, you can use a higher
output
> power diode such as a 20mW diode, limit the output power by
utilising an
> aprropriate resistor to limit the current so that the diode is
running at
> say 6mW and allowing for approximately 10% loss through the lenses
you are
> starting with an output power of 5.4mW. What does change however
between
> output powers, lenses used, whether the laser is pulsed (pulsed
will change
> the mean average output ) or continuous wave and where the diode is
sitting
> in the probe is the power density and hence the energy density
dosage given
> per treatment.
>
> The trick to all of this is what you are using the laser for in
relation to
> clinical applications. For example laser Acupuncture, or
neurovascular or
> neurolymphatic reflex points would typically only need a low output
power
> due to the superficial nature of the points being treated. For
standard
> musculo/skeletal remedial laser therapy much higher output powers
are used
> to gain deeper penetration into the tissue to affect a standard
remedial
> laser healing response. The use of laser therapy in relation to
> bioenergetic treatments is different again in that based on the
energetic
> level of what you are treating, the nature of tensegrity structures
and the
> treatment philosophy used; much lower powers can be used. At the
end of the
> day however, it is completely up to the individual practitioner and
their
> own experience and also based on what manufacturers are out there
and what
> target market the manufacturers are aiming the design of their
product too.
> No manufacturer is wrong in their design, just different.. And most
> manufacturers will modify specifications of a laser that is built
for a
> reasonable fee if the individual practitioner so desires.
>
> The difficulty for all laser manufacturers is to come up with a
laser with
> an appropriate beam diameter (ie: spot... Line etc) that covers
most
> requirements for clinical practice when it comes to laser therapy.
This
> isn't an easy thing to do hence most manufacturers will have a
range of
> probes and at the end of the day it is purely up to the individual
> application that the practitioner is using as I have said. Having
said
> this, there are a number of factors that are involved in the
nominal output
> power at the aperture of a laser probe such as:
>
> 1. Where the diode is situated in the probe: Some laser
manufacturers
> actually have the diode situated slightly back from the portion of
the probe
> that touches the skin (keeping in mind that most laser applications
are best
> applied with the laser in skin contact as this reduces any
reflection and
> loss of power from the skin etc) and some manufacturers have the
diode right
> at the tip of the laser probe so the diode is virtually in touch
with the
> skin (usually with a lense configuration of some type sitting over
the face
> of the diode). Depending on the lense use and where the diode is
situated,
> you may have vastly different power densities.
>
> 2. Obviously the output power of the diode.
>
> 3. Whether the diode is only a pulsed diode or whether the diode is
a
> continuous wave diode that can be pulsed. Pulsing will definitely
change
> the output power at the aperture based on duty cycles and pulse
rate.
>
> 4. Whether the diode is naturally divergent, collimated or focused
and what
> typical power losses occur through the lense used as all lenses
with produce
> some loss of output power.
>
> All laser diodes are naturally divergent with I think an
approximately 20 to
> 30 degree typical divergence across one axis and approximately 12
to 15
> degrees across the second axis being that most lasers utilise
elliptical
> beams, but this changes vastly depending on the manufacturer of the
diode
> and what it is manufactured for, however I think most diode source
rate
> their divergence in Milli Radians. Because of this reason, most
laser
> therapy probes will generally have a collimating lense which turns a
> divergent (widening over time) beam into a parallel line (rather
than the
> natural inverted cone shape of a divergent beam). This makes
output power
> and power density calculation much easier at skin contact in that
you are
> starting with a definite beam size! However, different lenses can
give you
> whatever configuration of beam that you wish, whether it be a very
small
> spot (focussing lense), a very neat stable beam size (collimating
lense) or
> a very large beam size (divergent lense). The last thing to
remember is
> that most laser therapy probe beam spots and lines are elliptical
beams not
> circular spots or actual rectangular lines. Lines produced by a
single
> diode will more often than not be an elliptical beam that has had
the
> circular edges cut off by the type of lense that is used.
>
> Before I use an example, the last thing I need to revise is the
power
> calculations (the real meat of the standard laser therapy story).
These
> are: Joules, Power Density (sometimes known as Power Intensity) and
Energy
> Density (sometimes known as Energy Intensity) . These three terms
regularly
> get mixed up and I must admit for the first few years of my "laser
therapy"
> life I struggled with them enormously!! The key to these is the
power
> density and as long as you definitely know the output power
>
> Joules is obviously an expression of laser energy. The calculation
for
> Joules is : Energy (Joules) = Mean Output Power (Watts) multiplied
by
> Treatment Time (secs)
>
> Power Density is a calculation to determine power of the laser for
the
> nominal beam size and is measured in Watts/cm. Sq: PD = Mean Output
Power
> (Watts) divided by Irradiated Area in sq. cm
>
> Energy Density is another Energy Calculation which is basically the
Power
> Density multiplied by Treatment time: Energy Density (Joules/cm
sq) = Mean
> Output Power (Watts) multiplied by Irradiation Time (secs) divided
by
> Irradiated area in sq cm.
>
> This may seem a little confusing at first but once you start going
through
> the calculations it does come easily enough.
>
> For an example, I will use a 5mW Laser probe with a beam diameter
> (elliptical beam) of 1mm x 2mm (let's call this the "laser spot"
from
> Steve's question) with the diode situated at the very tip of the
probe (so
> that skin contact will receive the energy that we calculate
specifically)
> with a treatment time of 10 seconds. If we go through our
calculations we
> find that:
>
> Power Density (Watts/cm2) = Mean Output Power (W) / Irradiated
area in
> cm2 (beam diameter)
>
> = 0.005 Watts (5mW) / 0.1cm x 0.2cm x
0.784
> (this is the calculation fro area of an ellipse)
>
> = 0.005 / 0.01568
>
> = 0.32 Therefore this 5mW laser has
a Power
> Density of 320mW/cm2
>
> Energy Density (Joules/cm2) = Mean Output Power (W) X Irradiation
Time
> (Secs) / Irradiated Area (cm2)
>
> = 0.005 (5mW) X 10 seconds / 0.01568
(from
> above calculation)
>
> = 3.2 Therefore this 5mW laser has an
> Energy Density of 3.2 Joules/cm2
>
> Joules = Mean Output Power (W) X
Treatment Time
> (secs)
>
> = 0.005 X 10
>
> = 0.05 Therefore this 5mW laser
applied for
> 10 Seconds will deliver a 0.05 Joules dosage
>
> For the second example, I will use a 20mW Laser probe with a beam
diameter
> (elliptical beam) of 1mm x 2mm (let's call this the "laser spot"
from
> Steve's question) with the diode situated at the very tip of the
probe (so
> that skin contact will receive the energy that we calculate
specifically)
> with a treatment time of 10 seconds. If we go through our
calculations we
> find that:
>
> Power Density (Watts/cm2) = Mean Output Power (W) / Irradiated
area in
> cm2 (beam diameter)
>
> = 0.02 Watts (20mW) / 0.1cm x 0.2cm x
0.784
> (this is the calculation fro area of an ellipse)
>
> = 0.02 / 0.01568
>
> = 1.28 Therefore this 20mW laser has
a
> Power Density of 1.28W/cm2
>
> Energy Density (Joules/cm2) = Mean Output Power (W) X Irradiation
Time
> (Secs) / Irradiated Area (cm2)
>
> = 0.02 (20mW) X 10 seconds / 0.01568
(from
> above calculation)
>
> = 12.8 Therefore this 20mW laser has
an
> Energy Density of 12.8 Joules/cm2
>
> Joules = Mean Output Power (W) X
Treatment Time
> (secs)
>
> = 0.02 X 10
>
> = 0.2 Therefore this 20mW laser
applied for
> 10 Seconds will deliver a 0.2 Joules dosage
>
> As you can see from the above examples, if a limiting resistor is
not used
> to bring the 20mW laser back down as Steve has suggested, the
treatment
> parameters will be quite different.
>
> For the third example, I will use a 5mW Laser probe with a beam
diameter
> (elliptical beam) of 1mm x 5mm (let's call this the "laser line"
from
> Steve's question) with the diode situated at the very tip of the
probe (so
> that skin contact will receive the energy that we calculate
specifically)
> with a treatment time of 10 seconds. If we go through our
calculations we
> find that:
>
> Power Density (Watts/cm2) = Mean Output Power (W) / Irradiated
area in
> cm2 (beam diameter)
>
> = 0.005 Watts (5mW) / 0.1cm x 0.5cm x
0.784
> (this is the calculation fro area of an ellipse)
>
> = 0.005 / 0.0392
>
> = 0.13 Therefore this 5mW laser has
a Power
> Density of 130mW/cm2 (nearly a 40% reduction from the spot size
> calculations)
>
> Energy Density (Joules/cm2) = Mean Output Power (W) X Irradiation
Time
> (Secs) / Irradiated Area (cm2)
>
> = 0.005 (5mW) X 10 seconds / 0.0392
(from
> above calculation)
>
> = 1.28 Therefore this 5mW laser has
an
> Energy Density of 1.28 Joules/cm2 (again approximately a 40%
reduction from
> the spot size calculations)
>
> Joules = Mean Output Power (W) X
Treatment Time
> (secs)
>
> = 0.005 X 10
>
> = 0.005 Therefore this 5mW laser
applied for
> 10 Seconds will deliver a 0.05 Joules dosage (notice the Joules
parameter
> doesn't change)
>
>
> For the fourth example, I will use a 20mW Laser probe with a beam
diameter
> (elliptical beam) of 1mm x 2mm (let's call this the "laser line"
from
> Steve's question) with the diode situated at the very tip of the
probe (so
> that skin contact will receive the energy that we calculate
specifically)
> with a treatment time of 10 seconds. If we go through our
calculations we
> find that:
>
> Power Density (Watts/cm2) = Mean Output Power (W) / Irradiated
area in
> cm2 (beam diameter)
>
> = 0.02 Watts (20mW) / 0.1cm x 0.5cm x
0.784
> (this is the calculation fro area of an ellipse)
>
> = 0.02 / 0.0392
>
> = 0.51 Therefore this 5mW laser has
a Power
> Density of 510mW/cm2 (right on the border between class3b and class
4
> lasers)
>
> Energy Density (Joules/cm2) = Mean Output Power (W) X Irradiation
Time
> (Secs) / Irradiated Area (cm2)
>
> = 0.02 (20mW) X 10 seconds / 0.0392
(from
> above calculation)
>
> = 5.1 Therefore this 20mW laser has
an
> Energy Density of 5.1 Joules/cm2 (an obvious reduction in energy
from the
> spot size)
>
> Joules = Mean Output Power (W) X
Treatment Time
> (secs)
>
> = 0.02 X 10
>
> = 0.2 Therefore this 5mW laser
applied for
> 10 Seconds will deliver a 0.2 Joules dosage (again this parameter
does not
> change)
>
> As we can see from the above examples, power densities and energy
densities
> will change with different output powers and will vastly affect the
energy
> delivery you are trying to achieve (Hence... Yes Steve, you will
lose
> significant amounts of power depending on the beam size of your
laser). I
> apologise for th elong winded nature of this response but I feel
it's
> important for everyone to know that the output powers are not the
only
> relative parameter to be aware of in that power density and energy
density
> calculations prove the difference of power gains or losses
depending on how
> your laser is set up). Again all of these factors are determined
by the
> variations mentioned above and need to be taken into consideration
when both
> choosing a laser to buy and what you want you laser to do and also
so that
> you know how to modify your treatment regimes based on knowing these
> parameters of the laser that you are using! All of the required
> specifications will be found in your laser operation manuals from
your
> manufacturer so that you can make these calculations.
>
> Another important point to remember is that while I am saying that
output
> power is only one aspect of the parameters you need to know, there
are two
> camps within the standard laser therapy world, one using Joules
dosage and
> one using Energy Density to calculate treatment delivery. As you
can see
> from the above examples, these differ when you do the calculations
so it's
> another thing to keep in mind. As stated above, this does not
necessarily
> relate to the more energetic uses of laser therapy directly but
still have
> some validity for reproducible results in some areas.
>
> I again apologise for the long winded response but hope that this
has been
> helpful in some way.
>
> Warm Regards
>
> Sean
>
>
>
>
>
>
> -----Original Message-----
> From: Therapeutic-Laser_Therapy@yahoogroups.com
> [mailto:Therapeutic-Laser_Therapy@yahoogroups.com] On Behalf Of
Jennifer
> Ruby
> Sent: Wednesday, March 15, 2006 1:34 AM
> To: Therapeutic-Laser_Therapy@yahoogroups.com
> Subject: Re: [Therapeutic-Laser_Therapy] Line vs Dot and power
output
> question..
>
> Hi Steve!
>
> I don't know the answer to this question.... Hoping someone with
laser
> manufacturing wisdom will give some insight to this question.
>
> Health, Hope, Joy & Healing :
> May you Prosper, even as your Soul Prospers 3John 2
>
> Jennifer Ruby
>
> Email advice is not a substitute for medical treatment.
>
> http://www.rubysemporium.com
> http://groups.yahoo.com/group/SymphonicHealth
> http://groups.yahoo.com/group/Therapeutic-Laser_Therapy
> http://www.lazrpulsr.com
> ______________________________________________
> «¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤
> ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
> ----- Original Message -----
> From: "esl5552001" <SCL555@...>
> To: <Therapeutic-Laser_Therapy@yahoogroups.com>
> Sent: Monday, March 13, 2006 1:56 PM
> Subject: [Therapeutic-Laser_Therapy] Line vs Dot and power output
question..
>
>
> | I have noticed that some lasers on the market (635nm healing
lasers)
> | use a dot and some lasers use a line. I have heard it said that
if you
> | are using a 5mw line then you are losing a significant amount of
power.
> | For instance the Erchonia is said to only produce .6mw output of
power
> | at the aperture. Wouldn't it make sense to just use 15-20mw diode
(or
> | whatever it takes) until you arrive at the desired 5mw output at
the
> | aperture for a line generated laser? Then you could cover more
area in
> | less time with greater effect using a true 5mw. Just trying to
arrive
> | at the bottom line of all this laser tech(pun intended).
> |
>
>
>
>
> --
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