We present in this paper fabrication, simulation and measurement of low refractive index micropilar/microcavity structures where the optical properties are retrieved by white light Fourier image spectroscopy [1]. We aim to show with these results that organic micropillars and low refractive index cavities in 3D photonic crystals could be a suitable platform for organic based emitting devices. We also will show that the Fourier image spectroscopy technique allows measurement of, not just the dispersion relation of the microcavity modes, but also the numerical aperture of micropillars.