Can Lightsheer Diode Laser Remove Very Fine Black Hairs?

Regardless of the caliber of the hair, as long as there is pigment the laser will work.  The target for the laser energy is the color, ideally, hair darker than the skin will respond.  A thin hair has less total pigment than a thick hair simply because it is smaller.  There is less target for the laser. This means that higher energy and/or more treatments will be needed to eliminate the tiniest hairs. You should see results but you may need more patience.

As long as the hair is dark in color the Lightsheer laser is the best. It works faster for coarser hair, just because there is more pigment to get absorbed by the light. The very fine black hairs might take a few more treatments, but the end result is great.

The greater the contrast between the hair and skin colour, the better the result.  The Lightsheer diode laser will remove fine black hair.