Wideband antireflection film fabricated by glancing angle deposition

Graded-index ZrO2 films has been fabricated on K9 glass by glancing angle deposition. Because the index mismatch at the interface has been reduced, the film results in wideband high-transmission antireflection. From 400nm to 1200nm, the film reflection is lower than 0.8% and the lowest value is 0.2% at 432nm.

Layer uniformity of glancing angle deposition

Some results of an investigation on the layer thickness uniformity of glancing angle deposition are presented. A zirconia monolayer has been deposited by glancing angle deposition to analyze the layer thickness uniformity. The experimental results indicate that the thickness variation over the substrate is less than 0. 1%, which is considered as good uniformity. It is found that the non-uniformity of experimental results is larger than that of the theoretical results. (c) 2005 Elsevier Ltd. All rights reserved.

Structure and optical properties of ZnS thin films grown by glancing angle deposition

The glancing angle deposition (GLAD) technique was used to deposit ZnS films by electron beam evaporation method. The cross sectional scanning electron microscopy (SEM) image illustrated a highly orientated microstructure composed of slanted column. The atomic force microscopy (APM) analysis indicated that incident flux angle had significant effects on the nodule size and surface roughness. Under identical nominal thickness, the actual thickness of the GLAD films is related to the incident flux angle. The refractive index and in-plane birefringence of the GLAD ZnS films were discussed, and the maximum bireffingence Delta n = 0.036 was obtained at incident flux angle of alpha = 80 degrees. Therefore, the glancing angle deposition technique is a promising way to create a columnar structure with enhanced birefringent property. (c) 2005 Elsevier B.V. All rights reserved.

Surface morphology and properties of zirconia thin films prepared at different deposition rates

ZrO2 thin films were prepared on BK7 glass substrates by electron beam evaporation deposition method. The influence of deposition rate varying from 1.2 to 6.3 nm s(-1) on surface morphology and other properties of ZrO2 films were examined. With increasing deposition rate, the surface defect density increased. The decrease in half width at full maximum in X-ray diffraction pattern with deposition rate indicates an increase in crystal dimension with increasing deposition rate. Electron beam deposited ZrO2 films are known to be inhomogeneous. From the change of the peak transmittance value, it can be deduced that the inhomogeneity of ZrO2 films strengthened gradually with increasing deposition rate. The type of surface defects changed from nodules to craters when the deposition rate was high enough.

The laser-assisted cold spray process

Thick metal coatings are currently deposited via two well established routes, Laser or arc based cladding, and thermal spray. A new coating technique known as Laser-assisted Cold Spray (LCS), which aims to expand on the capabilities of the two process routes currently available, is under development at the University of Cambridge in the UK. LCS is a development of the Cold Spray process (CS) in which coatings are built up from powder particles which are entrained within a gas stream and accelerated through a de Laval nozzle, impacting the substrate at supersonic speeds that exceed a material dependent critical velocity.

Graded index 532HR/1064HT filter by glancing angle deposition

Glancing angle deposition is a novel method to prepare graded index coatings. By using this method and physical vapour deposition, ZrO2 is used to engineer graded index filter on BK7 glass substrate. Controlling the deposition rate and the periodic oscillation of oblique angle of deposited material, a 10-period graded index ZrO2 filter with high reflection near 532 nm and high transmittance at wavelength 1064 nm is fabricated. The causes of difference between the theoretical and experimental results are discussed in detail. The material properties and electron gun nonlinearity are possibly the main origins of the difference, which result in the variations in both thickness control and deposition rate of the Elm material.

Structural and optical properties of nanostructured TiO2 thin films fabricated by glancing angle deposition

TiO2 films deposited by electron beam evaporation with glancing angle deposition (GLAD) technique were reported. The influence of flux angle on the surface morphology and the microstructure was investigated by scanning electron microscopy. The GLAD TiO2 films are anisotropy with highly orientated nanostructure of the slanted columns. With the increase of flux angle, refractive index and packing density decrease. This is caused by the shadowing effect dominating film growth. The anisotropic structure of TiO2 films results in optical birefringence, which reaches its maximum at the flux angle alpha = 65 degrees. The maximum birefringence of GLAD TiO2 films is higher than that of common bulk materials. It is suggested that glancing angle deposition may offer an effective method to obtain tailorable refractive index and birefringence in a large continuous range. (c) 2006 Elsevier B.V. All rights reserved.

Preparation of high laser induced damage threshold antireflection film using interrupted ion assisted deposition

Single layers and antireflection films were deposited by electron beam evaporation, ion assisted deposition and interrupted ion assisted deposition, respectively. Antireflection film of quite high laser damage threshold (18J/cm(2)) deposited by interrupted ion assisted deposition were got. The electric field distribution, weak absorption, and residual stress of films and their relations to damage threshold were investigated. It was shown that the laser induced damage threshold of film was the result of competition of disadvantages and advantages, and interrupted ion assisted deposition was one of the valuable methods for preparing high laser induced damage threshold films. (c) 2007 Optical Society of America