Patent ID: 7652762

Claim:
A support intended for observing between crossed polarisers an object placed on the support or in the vicinity thereof in a medium ( 3 ) of refraction index n 0 with spatially incident convergent spatially incoherent illumination under an angle θ 0 at a wavelength λ, including a substrate ( 1 ) of complex refraction index n 2 , and a layer ( 2 ) of complex refraction index n 1 and of thickness e 1 on said substrate, said substrate and said layer being in a medium of index n 0 and being configured for observation with spatially incident convergent non-coherent illumination under an angle θ 0 at a wavelength λ, said angle θ 0 being with respect to and axis normal to an observation surface of the support wherein, the value of the thickness e 1 of the layer ( 2 ) is within 2% so that: ⅆ 2 ⅆ e 1 2 ⁢ ln ⁢ ⁢  σ  2 = 0 with σ = σ 01 + σ 12 ⁡ ( 1 + π 01 ) ⁢ ⁢ ⅇ ( - 2 ⁢ j ⁢ ⁢ β 1 ) + σ 01 ⁢ π 12 ⁢ ⁢ ⅇ ( - 4 ⁢ j ⁢ ⁢ β 1 ) ( 1 + r 01 ⁢ ( p ) ⁢ r 12 ⁢ ( p ) ⁢ ⅇ ( - 2 ⁢ j ⁢ ⁢ β 1 ) ) ⁢ ( 1 + r 01 ⁢ ( s ) ⁢ r 12 ⁢ ( s ) ⁢ ⅇ ( - 2 ⁢ j ⁢ ⁢ β 1 ) ) a formula wherein σ ik and π ik represent respectively the sum and the product of the Fresnel coefficients of the different interfaces [(i,k)=(0,1) or (1,2)] r ik ⁡ ( p ) = n k ⁢ ⁢ cos ⁢ ⁢ θ i - n i ⁢ ⁢ cos ⁢ ⁢ θ j n k ⁢ ⁢ cos ⁢ ⁢ θ i + n i ⁢ ⁢ cos ⁢ ⁢ θ k and r ik ⁡ ( s ) = n i ⁢ ⁢ cos ⁢ ⁢ θ i - n k ⁢ ⁢ cos ⁢ ⁢ θ k n i ⁢ ⁢ cos ⁢ ⁢ θ i + n k ⁢ ⁢ cos ⁢ ⁢ θ k and ⁢ ⁢ wherein ⁢ ⁢ β 1 = 2 ⁢ ⁢ π ⁢ ⁢ n 1 ⁢ e 1 ⁢ cos ⁢ ⁢ θ 1 λ , ⁢ with ⁢ ⁢ cos ⁢ ⁢ θ 1 = 1 - ( n 0 n 1 ) 2 ⁢ ⁢ sin 2 ⁢ ⁢ θ 0 .