Dependence of readback output on medium thickness in the presence of a permeable underlayer--Part 2: Wavelength responses of probe heads in the presence of a permeable underlayer

A rigorous solution for the field of a model two-dimensional electromagnet is presented. This model is equivalent to those for a ring head with arbitrary gap depth and a probe head in the presence of a permeable underlayer. Based on this solution, the wavelength responses of probe heads with arbitrary dimensions have been calculated. It is shown that the readback resolution of probe heads is quite inferior to the resolution of ring heads with conventional medium.