Analogue difference holographic interferometry for two-wavelength contouring

Difference holographic interferometry uses holographic illuminations from the master object for the illuminations of the test object. The principle has been applied successfully for deformation measurement, phase object investigation and for contouring, as well – but in the last case within the two-refractive index method, only. Its application for contouring with the two-wavelength method is still missing – although it does exist already in the much later developed digital holographic interferometry.The present paper resolves this discrepancy and provides the better “analogue quality” by reporting the first realization of the analogue difference holographic interferometry in the two-wavelength contouring. Experimental evidence is presented not only for the existence of the application but for the numerical correctness of difference making, too. The measuring range extension achieved is threefold.