MEASURING WAVELENGTH DISCRIMINATION THRESHOLD ALONG THE ENTIRE VISIBLE SPECTRUM

The wavelength discrimination threshold can be characterized by the difference of two monochromatic lights´ wavelengths (Δ λ) that subject can hardly detect. The detection of small differences in hue, present in a colour simulation is of great interest from a scientific viewpoint. A new instrument was built to measure wavelength discrimination threshold. A bipartite light is located in 2° visual angles within a white adaptation field. A monochromatic reference light is projected into one half of the field, while an adjustable monochromatic target light is projected into the other half of the field. Both lights have the same brightness. The examined subject has to adjust the wavelength of the target light until the difference between the reference and the target light can be seen. Measuring wavelength discrimination threshold along the entire spectrum the Δ λ (λ reference light) function can be established. Wavelength discrimination threshold function describes the subject´s color discrimination ability. Our experiences with the newly set up instrument are presented in this paper