A method for the photothermal investigation of a sample (P), comprising the steps: a) irradiation of a first side of the sample (P) with an electromagnetic excitation pulse , b) detection of thermal radiation emitted from a second side of the sample (P) lying opposite the first side as a result of the excitation pulse , c) evaluation of the detected thermal radiation based on a model defined by the following equations: ∂ 2 T / ∂ x 2 = 1 / α × ∂ T / ∂ t for 0 < x < L , t > 0 k × ∂ T / ∂ x − h × T = − E t + η ′ × T 0 t − T L t for x = 0 , t > 0 k × ∂ T / ∂ x + h × T = − η ′ × T 0 t − T L t for x = 0 , t > 0 T x 0 = 0 for t = 0 wherein: T denotes the location- and time-dependent temperature of the sample, L denotes the thickness of the sample, x denotes the location coordinate viewed in the thickness direction of the sample, with x=0 at the first side of the sample and x=L at the second side of the sample, t denotes the time, with t=0 at the time of the excitation pulse, E(t) denotes the time-dependent radiation current density of the excitation pulse, α denotes the temperature conductivity of the sample, k denotes the thermal conductivity of the sample, h denotes the heat transfer coefficients at the sample surfaces, η' denotes an "overall transparency factor", wherein a mathematical compensation calculation is carried out, in which the parameter η' and one or more of the parameters α, k, h and/or parameters of the model derived therefrom are estimated on the basis of a course over time of the temperature T(L,t) at the second side of the sample (P) determined from the detected thermal radiation . a) irradiation of a first side of the sample (P) with an electromagnetic excitation pulse , b) detection of thermal radiation emitted from a second side of the sample (P) lying opposite the first side as a result of the excitation pulse , c) evaluation of the detected thermal radiation based on a model defined by the following equations: ∂ 2 T / ∂ x 2 = 1 / α × ∂ T / ∂ t for 0 < x < L , t > 0 k × ∂ T / ∂ x − h × T = − E t + η ′ × T 0 t − T L t for x = 0 , t > 0 k × ∂ T / ∂ x + h × T = − η ′ × T 0 t − T L t for x = 0 , t > 0 T x 0 = 0 for t = 0 wherein: T denotes the location- and time-dependent temperature of the sample, L denotes the thickness of the sample, x denotes the location coordinate viewed in the thickness direction of the sample, with x=0 at the first side of the sample and x=L at the second side of the sample, t denotes the time, with t=0 at the time of the excitation pulse, E(t) denotes the time-dependent radiation current density of the excitation pulse, α denotes the temperature conductivity of the sample, k denotes the thermal conductivity of the sample, h denotes the heat transfer coefficients at the sample surfaces, η' denotes an "overall transparency factor", T denotes the location- and time-dependent temperature of the sample, L denotes the thickness of the sample, x denotes the location coordinate viewed in the thickness direction of the sample, with x=0 at the first side of the sample and x=L at the second side of the sample, t denotes the time, with t=0 at the time of the excitation pulse, E(t) denotes the time-dependent radiation current density of the excitation pulse, α denotes the temperature conductivity of the sample, k denotes the thermal conductivity of the sample, h denotes the heat transfer coefficients at the sample surfaces, η' denotes an "overall transparency factor", <EOS>