We have built a simple and high performance inverse photoemission spectrometer using a BaF2window and a Cu–BeO electron multiplier with KBr as the photocathode for low‐ and high‐pass filters, respectively. It is found that using the BaF2low‐pass filter improves the resolution by 0.2 eV to compare with SrF2. The intensity was reduced to a quarter of that with SrF2, although it is enough to obtain good inverse photoemission spectra.