Over recent years, a research of wide-band light interference has led to new hope for three-dimensional fluorescence detecting without scanning. The research is the Fresnel incoherent correlation holography (FINCH) based on splitting light with a spatial light modulator (SLM). However, the conventional FINCH system is not that much effective to record weak fluorescent signal. It is mainly because the key parameter, optical path difference (OPD), that affects wideband light interference is not small enough. We note that the OPD can be decreased by adopting a spherical reference wave whose focal length is close to that of the object wave. And the hologram recordable area can be shifted from the area that is at a long distance from image plane to its neighborhood. This leads to the improvements of signal-to-noise ratio (SNR) of images and makes this method more suitable for recording weak fluorescent signal. In this investigation, we analyze the OPD character of this fluorescence holographic system and present how the OPD effects the choosing of experimental parameters to obtain high quality interference patterns. We also find that the central part of a wavefront is more likely to be decoded compared with the edge part.