Refractive index or Abbe number (νd or νe) can be measured atdifferent wavelengths ranging from 450 to 1,550nm. This refractometer digitallys display measurement result of refractive index or Abbe number on the LCD. This measurement can be achieved by matching the boundary line with the intersection point of the cross hairs. This is connectable with Digital printer DP-AD(B) (Optional).