Abstract: Method for checking the surface and/or shape of at least one surface, or part thereof, of an object made of transparent material, by means of a checking system which comprises a light source, a sensor and a processing unit connected to the sensor. By an appropriate positioning of the light source and sensor it is possible to overcome the problem of multiple reflections and to identify in a unique manner the rays scattered from the surface to be checked and received by the sensor which are useful for the purposes of checking. According to one of the embodiments, it is also possible to determine the thickness of the object to be checked.

Abstract: Method for checking the surface and/or shape of at least one surface, or part thereof, of an object made of transparent material, by means of a checking system which comprises a light source, a sensor and a processing unit connected to the sensor. By an appropriate positioning of the light source and sensor it is possible to overcome the problem of multiple reflections and to identify in a unique manner the rays scattered from the surface to be checked and received by the sensor which are useful for the purposes of checking. According to one of the embodiments, it is also possible to determine the thickness of the object to be checked.

Abstract: A device measuring the optical absorption in thin layer materials by using the photothermal deflection spectroscopy (P.D.S.) comprises a laser source, an optical doubler between the laser source and the probe intended to divide the laser beam in two equal, parallel measurement and control beams, a cylindrical lens between the doubler and the probe, and a pair of position sensors which receive the beams focused by said lens and send them to an electronic circuit supplying a signal output which is not influenced by the noise due to the instability in the direction of the analyzer beam and to the mechanical vibrations.