Can Laser/Maser Pass Through Tissue without Interacting?

[Thiago]

Can some kind of Laser/Maser pass (not interacting) through a large amount of tissue?

I know that some medical lasers can penetrate over 10cm of tissue, and the visible ones stop almost in the skin surface.

the problem resides (til I've understood) in the problem that penetrating lasers tend to be highly absorbed by water molecules.

 

[mikeph]

Sure, just chose a wavelength with high transmission through a human. My guess would be radio waves. I don't think radio wave lasers exist though.

Water does absorb a lot of frequencies, but not all of them.

 

[Thiago]

Radio waves lasers exists, but water absorbs radio waves a lot, (thats why radio can't be used by subs)

This was one of my first toughs.

 

[DaveC426913]

Well, an X-ray laser would work...

 

[Thiago]

I tend to believe that one x-ray laser will cause some kind of harm at the tissue Dave, I really can't explain why (probably some bias of my part), I also don't know if x-ray lasers exists, I know instead that FEL (free-electron lasers) can be tuned in x-ray frequencies.

Do you know some paper about the theme Dave? Tissue related experiences mostly.

 

[DaveC426913]

I tend to believe that one x-ray laser will cause some kind of harm at the tissue Dave,

Yes. My bet is that any EM that can pass through a thickness of tissue is also energetic enough to damage it.

 

[mikeph]

Radio waves lasers exists, but water absorbs radio waves a lot, (thats why radio can't be used by subs)

This was one of my first toughs.

Certainly in the microwave region , but I think with a long enough wave (energy below fundamental rotation transitions) it should pass straight through... wiki: "VLF even penetrates sea-water".

 

[Thiago]

MikeyW,

True, they use VLF, but, I don't know a laser that use this kind of wave, even if it is feasible.

Don't you agree?

 

[xts]

Any reason to insist for laser-like solution?
Can't be just some electronics and antenna?

 

[Thiago]

Resolution and accurateness, if it was just pass waves, any thing like pet scan or tomography would suffice.

 

[xts]

Resolution and accurateness, if it was just pass waves, any thing like pet scan or tomography would suffice.

Can you explain what is more accurate in maser than in electronic generator with apropriate antenna running at the same frequency? Or what is more acurate in red light made with laser than with LED? And what maser does more than 'just passing waves'?

 

[Thiago]

http://en.wikipedia.org/wiki/Optical_coherence_tomography

something like it xts.

but, why do you ask that kind of question? it's like if I've asked if a plane can travel the Atlantic? and instead of answering it you ask me why don't I go by boat?

 

[xts]

why do you ask that kind of question? it's like if I've asked if a plane can travel the Atlantic? and instead of answering it you ask me why don't I go by boat?

Yeah. Maybe it is not a best metaphore, but if we live in 1920, and I would get impression that your goal is to get quickly to New York, I would wonder why you ask about airplanes, rather than thinking about steamliners or maybe zeppelines.

If you think about some kind of imaging, like you may get using optical coherence tomography, you should rather forgot about masers and hypothetic radio-lasers running at 100kHz frequencies.
You require wavelengths smaller than desired resolution of your imaging. OCT (as says the wiki page you quote) resolution is 10 times worse than wavelength. Theoretical limit is wavelength.

Such requirement redefines your original question: only waves of wavelenghts of 1mm or less should be considered.

 

[Thiago]

Ok I understood.

But let's go one problem at time. first I need to know if there is some kind of laser that can penetrate tissue without causing any harm.

I suppose I made a mistake radio-wave laser don't exist. Sorry.

 

[xts]

I still don't understand why you insist on laser-like solution. The resolution gain comparing to "classical" sources is not big, while restricts you to very limited range of frequencies.

Sub-milimeter microwaves won't penetrate body deeper than few mm, the same for visual band and ultraviolet. Only remaining band are X-rays and up (gamma), which, at low intensity do little harm. X-ray tomography is considered safe.

 

[Thiago]

the reason was that I was thinking in holograph (the real one not the movie one), then I remembered that we need one reflex of a laser, but I'm wondering if we can reconstruct the img with a laser that passed trough some thing, them since we use tomography i thought if it wouldn't be cool to have one holo of our heart ^^

If it's possible, I want my share in the patent^^

 

[Philster371]

TeraHz imaging systems penetrate tissue and are non-ionising
42 patents - most still applications are owned by Teraview.