"Photosynthetic" radiation is the part of the spectrum which is used in photosynthesis e.g. 300-700 nm. The range of wavelengths could be specified precisely by the bounds of a coordinate of radiation_wavelength. Omnidirectional spherical irradiance is the radiation incident on unit area of a spherical (or "4-pi") collector. It is sometimes called "scalar irradiance". Radiation incident on a 2-pi collector has standard names of "spherical irradiance" which specify up/downwelling.