Hair-holder, hair-reader comprising the same, and methods for optically acquiring data from hair

A method for optically acquiring data from hair, the method comprising:

• providing a hair-holder including:
• upper and lower plate assemblies respectively having downward-facing and upward-facing opposing surfaces defining a fixed gap therebetween defining a gap therebetween, the lower plate assembly having a window-void therein, the upper plate assembly further comprising a sideward-facing sample-thickness-regulating surface above the gap;
• and
• an alignment-wall mechanically coupled to both plate assemblies and having a side-facing alignment surface within gap or sideward-facing into the gap, the alignment surface being straight along a longitudinal direction parallel to both of the opposing surfaces;
• receiving an externally-tensioned sample of hair onto the hair-holder such that the externally-tensioned sample of hair is laterally moved towards the alignment surface and a presence of the sideward-facing sample-thickness-regulating surface regulates an amount of hair permitted to enter the gap, thereby regulating a thickness of hair above the window-void to a fixed value of at least 0.5 mm and at most 2mm;
• and
• after the loading and after release of the external tension, the side-facing alignment surface applies static friction upon shafts of the hair sample so as to maintain alignment of hair above the window-void.