Figure 3
From: Optically Guided Epidural Needle Placement Using 405-nm Wavelength for Accurate Puncture
Optical-guided Location Device data displays. When reflection intensity is 0 meaning no reflected light received, in this case color bar will be green; When reflection intensity reaches 255 the color bar will turn yellow meaning needle tip has reached fat layer tissue; When reflection intensity decreases with advance of needle tip and drops to zero color bar will turn red bar indicating that the needle tip has reached the epidural space.
