A support designed for observing between intersecting polarizers an object located in its vicinity in a medium (3) of index n0 with incident convergent incoherent illumination under an angle θ0 at a wavelength λ. The support includes a substrate (1) with complex refractive index n2 and a layer (2) of refractive index n1 and thickness e1. The value of the thickness e1 of the layer (2) is at ±2% such that d2√/de21 lnIóI2=0 with Ó=Ó01+Ó12 (1+π01)e(−2jβ1)+Ó01 π12e (−4jβ1)/1+r01(p)+r12(p)e(−2jβ1))(1+r01(s)r12(s)e(−2jβ1)). Observation devices incorporating such a support are also disclosed.