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llarava
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HBA fiber optic light - can be seeing directly from the transceiver?

Can you see the light directly from an HBA card that’s connected to a transceiver (looking through the transceiver back of the servers hba) or do you need a FC cable-connected to be able to see the light on the end of the cable?
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andyalder

8/22/2022 - Mon
Dr. Klahn

Fiber wavelengths used for Fiber Channel are 1310 nm (infrared) to 1550 nm (deep infrared).  You won't see either of them without a night-vision viewer, and then probably only in a dark room.
andyalder

You can use the camera on your phone.Although it will be in low power mode when not connected it's still enough for a digital camera to pick up.
noci

It might not be wise to look into laser light. Too long exposure will hurt tissues. 

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andyalder

That's one reason they use low power mode until comms is established.
Dr. Klahn

noci has a very good point.  When I started holography as a hobby I thought "A two milliwatt laser is certainly harmless."

Consider a two milliwatt laser with a spot 1/2 millimeter by 1/2 millimeter.  The equivalent irradiance is 8 kilowatts per square meter.  This is 8 times the irradiance of the sun.  It takes very little time to permanently damage the retina at those power levels.

Never look into communication fiber optics.  Not if there is nothing connected at the other end, not if the transmitter is off.  Somebody can always flip a switch at the other end.  And since the infrared beam is invisible to the eye the damage will occur without even knowing it.
llarava

ASKER
so the answer is yes you will be but will be very weak and possibility difficult to see? i understand the risks.
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llarava

ASKER
ok, so when the HBA is connected  to a fiber aqua cable does the same apply to it? can you see the light in a dark room?
andyalder

It does not matter what the colour of the cable is but aqua is multimode which operates between  850 and 1300 nm, The human eye will respond to wavelengths from about 380 to 740 nm so your eye cannot see it, If you have a pet python you could ask that to tell you if it was on or not or you could carry a jar of pyrophilous insects with you and see if they move towards it (but a smartphone is more convenient).
llarava

ASKER
smartphone sounds the best option, it’s interesting because I’ve always been able to see light when connected to a fiber cable, again not a lot but some but I was curious to know if you could see it from the directly transceiver connected in the port of the HBA? do you think that one is easier than the other to see?
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rwheeler23
andyalder

You may have very sensitive eyes, https://www.ecmag.com/section/systems/tester-your-pocket says some people can see multimode.

Is it red light you see? With some HBAs you can see a red/purple glow but that does not travel through the fibre.
andyalder

"Can you see the light directly from an HBA card that’s connected to a transceiver (looking through the transceiver back of the servers hba) or do you need a FC cable-connected to be able to see the light on the end of the cable? "

Yes, you can see the light if it is a LED in the transceiver because a LED's emission is not a single frequency but a fairly broad spectrum. The visible light is outside of the bandwidth of the fibre so you can't see it at the end of the cable,