Rifle Scopes Off-topic green laser question

[mdmp5]

I lack the energy to even attempt to search for the answer for this, as it is at least a few years until google figures out how to emulate HAL 9000. I was in urology yesterday, and they were performing a TURP with a green laser machine. Apparently, the diode outputs a green laser through a fiber optic wire that glows really bright. The camera display is on a screen, showing the inside of the patient's urethra and bladder. The purpose of the TURP procedure is to ablate tissue of the prostate gland from the inside of the urethra, so that any obstruction to urine flow is relieved.

Anyway, on the screen, the laser output appears red. If the diode is emitting green, how is it possible to switch to red on the output? Seems to defy physics, since it is not fathomable how you can transform 1 wavelength of light into another. I asked the urologist, and he had no clue. Any of you guys have any ideas?

 

[condor22]

Re: Off-topic green laser question

Just a guess here. Colors on video displays can be changed by the Tint control on television, for instance. In this case, probably by software changing the green input video of the laser to red output video onto the display?

 

[zenbiker]

Re: Off-topic green laser question

Hmmm. Lasers are a big part of how I make a living; the laser used in TURP is a 532nm Nd:YAG or Nd:YP04 frequency-doubled diode; a much higher power version of the same green lasers currently marketed for firearms.

This wavelength of laser is highly absorbed in blood, making it a good choice for this type of surgery in that it clots the blood vessels up to a certain size as it melts/burns away tissue.

The red appearance: Condor's explanation is as good as any; another explanation is that you may be seeing a low power red aiming laser that shows the operator what tissue the green laser will ablate before it is activated. This is a common feature on medical lasers. Especially when doing delicate procedures like TURP, you <span style="font-style: italic">definitely</span> want to know what you're going to remove <span style="font-style: italic">before</span> you start to cut...