GentleMax Pro Plus Hair Removal Parameter Guide

The first installment in a three-part hair removal series.

The Parameter Guide delves into everything about laser hair removal parameters, including intensity (J).

A scene from a hair removal treatment

0. "몇 줄로 진행되나요?"

This is the question most frequently asked by people who have done some research on hair removal treatments.

My own hair removal card that I can view anytime, anywhere

At our clinic, we use all parametersare recordand track satisfactionand issuesfrom the previous session and send them via your cell phone, so you can view them conveniently at any time.

And... there's a very important reason why I started this.

The goal is to scientifically collect data that will provide a clear summary of the “laser hair removal parameters” that everyone is curious about (I’ll share the results in my next post!!)

First, the five major parameters of a laser are as follows.

1. Wavelength

2. 펄스폭(pulse duration)

3. Diameter (spot size)

4. Pulse Interval

5. Fluence

Shall we take a closer look at each one?

Since it would be too complicated to list information on every laser, I’ll focus solely on the laser parameters!

1. What is wavelength (nm)?

Source: "Parameters and Selection of Skin Lasers," by Lee Jae-dong

"Why 755 nm?"

There are various wavelengths used for hair removal, such as 755 nm, 810 nm, and 1064 nm, but

I prefer 755 nm the most. The reason is that it reacts most selectively with the melanin pigment found in facial hair.

(In the figure above, the range between 600 and 800 has a high absorption rate for purple melanin pigment. Although the ruby laser has higher selectivity, its shorter wavelength makes it difficult to penetrate to the skin layer where hair follicles are located; therefore, 755 nm is the most ideal wavelength.) 

At wavelengths of 1200 nm or less, the higher the wavelength, the greater the penetration depth. Source: dailyvet

Although the 1064 nm wavelength is sometimes used for deep facial hair, the 755 nm wavelength is the most stable and produces the best results, which is why most clinics use this wavelength.

2. 펄스폭(ms)이란?

펄스폭은 쉽게 말해 레이저가 나가는 시간단위 길이를 의미하며 주로 사용하는 펄스폭은 2ms, 3ms, 5ms, 10ms, 20ms가 있습니다.

"펄스폭이 왜 중요할까요?"

레이저의 타겟에는 고유의 타겟 펄스폭이 존재합니다(TRT라고 하며, 해당 조직이 레이저에 의해 가열된 후 열이 확산되어 퍼지는 시간을 의미합니다. 이 시간보다 길게 레이저가 조사되면 원하지 않는 부작용을 입을 수 있으며, 짧으면 원하는 효과가 나오지 않을 수 있습니다...! 복잡하므로 제모 설명에선 패스..)

간단히 말하자면, 이 원리 때문에 얇은 털일수록 펄스폭은 짧게, 굵은 털일수록 펄스폭은 길게 하는것이 좋습니다.

Even within the same area, hair thickness and follicle thickness can vary.

얇은 털의 모근은 얕고, 굵은 털의 모근이 깊은 것이 일반적이나 그렇지 않은 경우가 있습니다. 대표적으로 별로 굵지는 않은데 아무리 제모레이저를 반복해도 유독 빠지지 않는부위가 그 예시입니다. 이런 털은 펄스폭을 길게 하면 빠르게 제거됩니다.

"그럼 무조건 펄스폭을 길게 하면 모든 털이 반응하지 않나?"

펄스폭이 길어지면 같은 에너지가 들어갈 때 '단위시간'당 에너지값은 낮아지게 됩니다.(즉, 아래의 면적이 같을 때(=같은 에너지로 쏠 때), 시간이 줄어들수록 peak power(최대파워)가 올라갑니다)

펄스폭이 줄어들면, 최대 강도(peak power)가 올라간다.

그러므로 펄스폭은 무한정 길어져선 안되며, 제모에 적절한 조사시간은 2ms(매우 얇은 털) ~ 20ms(매우 굵은 털) 정도의 범위 입니다.

3. What is diameter (mm)?

"What is the ideal diameter for facial hair removal?"

The most commonly used diameters are 18 mm, 20 mm, and 24 mm.

The advantage of a narrow diameter is that it allows for detailed work in every nook and cranny.(It’s the same principle as being able to sweep every nook and cranny with a small broom.)

The advantage of a larger diameter is that the laser can penetrate deeper, and the procedure time is shorter. 

On the other hand, the disadvantage of a small diameter is that the laser cannot penetrate to a sufficient depth.

The disadvantage of using a large diameter is that, due to the nature of the facial area—which has many curved surfaces and features (such as the eyes, nose, and mouth)—it is difficult to cover the entire area if the diameter is too large.

레이저의 직경에 따른 침투 깊이 차이 (출처 : Ash, C., Dubec, M., Donne, K. et al. Effect of wavelength and beam width on penetration in light-tissue interaction using computational methods. Lasers Med Sci 32, 1909–1918 (2017). https://doi.org/10.1007/s10103-017-2317-4)

This is a famous paper. The laser’s diameter is 20 mm, there is virtually no difference in penetration depth even if the diameter is larger than that.

즉, 18mm는 시술시간이 길어져서 통증을 느끼는 시간이 함께 길어지고, 24mm는 구석구석 모든 범위를 커버하기가 힘듭니다. 

"In that case, 20 mm is the most ideal."

A 24mm spot size is best for body hair removal. Since there are few structures to be concerned about on the body, a larger spot size is preferred because it allows for greater laser penetration and reduces treatment time.

4. What is the sampling rate (Hz)?

The scanning frequency refers to how many times per second the laser is emitted.

Among the parameters for hair removal lasers, this is the one that is practically the least important.

Most are between 1 Hz and 2.5 Hz, and this does not significantly affect the results.

5. What is intensity (J)?

"How Many Lines? Why This Is a Half-Baked Question"

Key Parameters of Hair Removal Lasers Key Parametersand a parameter that many people are curious about.

To put it simply, the higher the intensity, the hair removal effectivenessincreases, and so do the risk riskalso increases.

Therefore, selecting the most appropriate intensity is of the utmost importance for hair removal laser treatments that maximize effectiveness and minimize side effects.

However, when looking at intensity, you shouldn't consider this figure in isolation. 

Since the total intensity increases as the diameter increases, the intensity must decrease, and,

Since the maximum intensity increases as the pulse width decreases, the intensity must also decrease.

"펄스폭이 줄어들면, 최대 강도(peak power)가 올라간다."

I’ll explain this in more detail using the graph below.

펄스폭이 줄어들면, 최대 강도(peak power)가 올라간다.

같은 강도(Fluence, J/cm^2)라도 펄스폭이 늘어나면 면적값은 같으므로 y축인 power는 증가하게 됩니다. 

즉, 펄스폭이 짧을 땐 강도를 낮춰야 하고 펄스폭이 길 땐 강도를 높혀야 합니다.

(그럼 굵은 털은 큰 모낭을 타겟하기 위해 펄스폭을 늘려야하고, 이에 따른 peak power는 낮아지기 때문에 강도는 올려야 하고.. 복잡하죠?^_ㅠ)

"As the diameter increases, the total energy increases."

The reason is that the unit of laser intensity is J/cm². 

Since this represents energy per unit area, the total energy increases as the area increases, assuming the intensity remains the same. 

The guidelines table below also states that, under the same conditions, you should set the intensity lower as the spot size increases.

General guidelines. Why did they write them down only in general terms?

The guidelines above do not specify a fixed value for fluence but instead provide a range. Why is that?

Since the parameters vary depending on the condition of the hair and skin, 

In a well-equipped hospitaluse higher intensities and personalized parameters. 

This is why hair removal is less effective when performed at a constant intensity.

In addition, even from an official standpoint, the skin’s reaction to the hair removal laser skin’s reactionand and gradually increase the intensity. 

"The choice of laser energy for hair removal depends on the condition of the hair, the condition of the skin, and whether there are any side effects,

"A comprehensive assessment of the parameters—energy, diameter, and exposure time—must be conducted."

So far, I’ve explained the parameters of the GentleMax Pro Plus hair removal laser, which many of you have been curious about.

In our next post, we’ll cover the core of our clinic: hair removal card, and 

Using the data accumulated through this hair removal card, I’d like to discuss.

If you have any questions, please leave a comment, and I’ll be happy to answer them in detail.

Thank you for reading this far.