FiberSafe Microscope eye safety

The Fibersafe Microscope improves the state of the art of eye safety by adding optical filters in both the red and near infra-red regions.

Three major improvementsMicroscope VFL Red Filter

  1. The maximum safe input power is printed on the instrument. So, a user can check actual power levels aginst this if ever needed.
  2. The safety filtering is improved compared to other microscopes. An additional filter attenuates VFLs, 850 nm and pump lasers. The high safe power level (0.1 - 1 Watt, or +20 to + 30 dBm) is above that of operational systems which have connectors.
  3. Safety Filter integrity: If the infra-red filter fails (eg broken or absent) the instrument is useless, since there will be no image. The additional filter integrity is easily inspected by removing the eyepiece (picture shows filter in place)

The video capture option is intrinsically safe.

What is the maximum possible system power?

The highest possible optical power level in a single mode system is limited by connector damage. Continuous operation of a typical single mode connector above about +20 dBm has been found to cause damage due to the extreme power density heating the ferrule tips. The maximum fault power output of optical amplifiers for line operation is never more than +24 dBm, to avoid destroying the attached fiber system by "fiber fuse" etc.

To exceed eg +24 dBm even temporarily requires that the microscope is irrelevant, eg the system must be all spiced with no connectors, or use expanded beam connectors. The total allowable power in an expanded beam would be somewhat higher, owing to the larger area. At time of writing, Diamond have a high power connector with 35 dBm power capability.

Therefore the FiberSafe Microscope eye safety handily exceeds the maximum possible system power.

Safety standards compliance

The ISO60825-2 2021 eye safety standard limits are summarized here.

For practical eye safety, the power level exiting the microscope eyepiece must be either Class 1 or Class 2.
Eg < 2 mW for Class 1 @ 633 nm or above, or < 5 mW for Class 2 visible light

This microscope is 100% eye safety tested during production using traceable instruments, to ensure maximum eye safe power handling is 
640 - 680 nm: 60 mW / 18 dBm (visible red), which exceeds Class 3R (note: the most powerful VFL available is 50 mW @ 650 nm)
680 - 1700 nm: Class 3B (infra red)

 

An attenuation graph showing 1000nm attenuation of 76db for the fibersafe microscope, and 30db for competitors.

 

FiberSafe Instruments

Not sure?