The value of diffuse reflectance spectroscopy for infrared analytical methods has some limitations caused by the low throughput efficiency of commercial accessories. We have redesigned a home-built diffuse reflectance accessory with an on-axis ellipsoidal collecting mirror which can also have benefits for the analysis of bulky samples. For illumination, use is made of the Circle cell optics which fits by adaption into the cone with a half angle of 30 degree(s) not considered for detection. Special features of the accessory are discussed, especially in view of our applications to the study of human tissue.