Abstract: The present invention relates to a method and an apparatus for measuring the thickness d of a transparent layer (10), and in particular to a method and an apparatus for measuring the thickness d of glass plates during wet-chemical glass thinning in the manufacturing process. The method for measuring the thickness d of a transparent layer (10) includes: determining an approximate thickness dFFT based on a precisely known dispersion n(1) of the material of the layer (10) by performing Fast Fourier Transformation, FFT, analysis on Fabry-Pérot oscillation, FPO, from the layer (10) in a spectral reflectance measurement (900); and performing a FPO full-spectral fitting procedure (910-0) with the approximated thickness dFFT as starting value d0,0 to determine an initial local best fitting thickness dFPO,0.

Abstract: The present invention provides for an apparatus for measuring a curvature of a surface of a wafer in a multi-wafer epitaxial reactor.

Abstract: A flat light emitting plate, a method for calibrating a pyrometer and a method for determining the temperature of a semiconducting wafer inside a processing chamber by said pyrometer. The invention provides a method for calibrating a pyrometer by means of a cold source which is also applicable to processing chambers with a narrow slit. According to the invention, a flat light emitting plate for simulating thermal radiation is provided, comprising a main body made of a transparent material, a light emission area located on an upper surface of the light emitting plate for emitting light, at least one light source located on a lateral surface of the light emitting plate, at least one detector located on a lateral surface of the light emitting plate, and a regulating circuit for adjusting the intensity of light emitted by the light sources.