The new method of measurement of monochromatic flows of radiation by means of two-diode configuration of self-calibrating photodiodes, which is based on the measurement of photodiode reflectance, is proposed. The proposed method has the advantage over the traditional design of trap-detector, which is related with the possibility of measurement of non-coherent radiation of the wide directional diagram. This method is also proposed in the traditional design of trap-detector for determination and registration of the portion of the measured radiation flow that is reflected from the receiver, for this the corresponding methods of measurement are proposed. The design allows using both the traditional three-diode configuration, and the described two-diode configuration. The results of the research of corrections for the proposed methods of measurement related with the change of s and p components of the radiation flow at the reflection from the photodiodes are given, for this the measurements of spectral reflectance for s and p components of the radiation flow in the wavelength range of 500 to 800nm were conducted. Besides, the influence of radiation polarization on the measurements uncertainty was analyzed. The experiment results of comparison of the proposed design and the traditional one of the trap-detector with the account for the portion of reflected radiation are given. The difference was not more than 0.071% at conducting measurements in the wavelength range of 500 to 800nm.