|
With the development of high energy laser, optical thin films used in this laser system are required with higher qualities which include the weak absorption and its uniformity. When the films are irradiated by a sufficiently energetic laser pulse, any local point on films which has more strong absorption may be damaged. In addition, the absorption uniformity of bistable thin films is also required because the different bistable properties occur at the different absorption points. Therefore it is very important for detecting correctly the absorption distribution on optical thin film and providing trustly the information for the coating of optical thin films. There are various techniques [ 1] for measuring weak absorption on thin films, but most of them are local measurements and difficult to detect the absorption distribution on the whole surface of films. Since the early 1980, scanning photothermal microscopy (SPIM) which based on the photothermal effect has been developed [ 2] . It can not only detect the absorptivity in the localized region of a sample in fast and high sensitivity by using a simple experiment setup, but also easily measure the absorptivity distribution on the whole surface by scanning the sample. Therefore, it is a novel technique for measuring the absorptivity distribution on optical thin films with the prospect of development and application.
|
