Synthetic diamond, deposited by Chemical Vapour Deposition (CVD), is becoming an interesting alternative for ZnSe as a window material for high power CO lasers. Although the infrared absorption of CVD-dianiond is higher than of ZnSe, this drawback is largely overruled by its better thermal conductivity, leading to smaller temperature gradients in the window and hence a less distorted laser beam. Electronic Speckle Pattern Interferometry (ESPI) is applied to study the on-line deformation of ZnSe and CVD-diamond anti-reflective coated output coupler windows exposed to a high power CO laser beam. It is seen that a ZnSe window already starts deforming at moderate beam power (100 W), while a diamond window does not deform considerably up to a beam power of 700 W.
A technique and device for recording and copying reflection holograms (Denisyuk's holograms) with a semiconductor laser, emitting in the visible spectral range ((lambda) equals 672 mm), are described. Superfine-grain silver halide Bulgarian materials HP-650 are utilized, ensuring high values of diffraction efficiency without bleaching after development. The major operating characteristics are determined and the possibility of holographic recording of real objects with vertical and horizontal positioning is demonstrated. The technique and device can find application in the realization of replicas of museum items, unique and rare specimens in the premises where they are stored, or archeological excavation findings during excavation, without the need of transporting the objects to the holographic laboratory.
We report on the characterization of the refractive index homogeneity in large blanks of Czochralski-grown Germanium, for thermal imaging use. With a phase-measuring Twyman-Green interferometer working at 10.6 micrometers , a map of the index of refraction with an accuracy better than 1 10<SUP>-5</SUP> can be obtained for blanks which do not exhibit high birefringence.In the other case, principal stresses in the disks can be determined through the effect of birefringence on the interferogram, if the stresses are distributed cylinder-symmetrically in the plane of the disk. Relations between stresses, transmittance, and electrical resistivity of the material are observed.
We report on the characterization of infrared materials using a phase measuring Twyman Green interferometer at 10.6 micron. Parameters studied are refractive index, wavefront distortion and optical homogeneity. The materials which were considered are CVD diamond, germanium and zinc selenide. Residual stresses coming from the manufacturing process and thermal stresses generated by absorption of carbon-dioxide laser light were measured and modeled.