When test force is F (mN) and an indentation depth in a sample is h (µm), dynamic hardness (DH) is defined by the following formula:
DH =a*F/h^2 [kgf/mm^2]
For the triangular 115 indenter (Berkovich indenter):
a= 3.8584
FYI: https://www.shimadzu.com/an/products/materials-testing/hardness-testing/duh-210duh-210s/features.html
Any idea on how Shimadzu engineers came up with 3.8584?! Just wonder seeing the formula and calculation..