Constant ZERNIKE_UNIT_PEAK 

pub const ZERNIKE_UNIT_PEAK: u8 = 0;

Leave the radial polynomial unnormalized: $R_n^m(1) = 1$ for every mode.

Coefficients then read as peak wavefront amplitude in whatever unit rho is measured against. See the module docs for the trade against ZERNIKE_ORTHONORMAL.