A new versatile ratio recording spectrophotometer with double detectors has been developed for measurement of absorption spectra of any transparent, translucent or opaque materials in U .V.and visible region.Sharp absorption bands of translucent materials can be obtained by placing the sample and the refrence closely to the end-on photocathodes of photomultipliers to capture all of the transmitted light beams.In the measurements of opaque materials, the light diffusely reflected from the sample is captured by the detector, and the light specularly reflected on the surface is totally left out of measurement.One can thus obtain sharp absorption bands even of glossy meterials.The instrument accommodates both electronic and optical systems to measure highly dense materials and to set the base line of a spectrum on any level of the absorbance scale.The scale can be expanded to measure difference spectra precisely.