Kenneth C. Jungling

Properties of TiO2 and SiO2 thin films deposited using ion assisted deposition

TiO2 and SiO2 films deposited using ion assisted deposition are investigated as a function of ion energy and current density. Optical constants, possible ion source contaminants, and optical scatter are examined for samples deposited at ambient (∼75°C) and elevated (∼250°C) substrate temperatures.

Float-polishing process and analysis of float-polished quartz

A fluid-mechanical model is developed for the float-polishing process. In this model laminar flow between the sample and the lap results in pressure gradients at the grooves that support the sample on a fluid layer. The laminar fluid motion also produces supersmooth, damage-free surfaces. Quartz substrates for applications in high-stress environments were float polished, and their surfaces were analyzed by optical scatterometry, photoacoustic spectroscopy, and atomic force microscopy. The removal of 100 µm of material by a lapping-polishing process, with final float polishing, left low levels of subsurface damage, with a surface roughness of approximately 0.2-nm rms.

Subsurface damage identification in optically transparent materials using a nondestructive method

Total internal reflection microscopy has been applied to image subsurface damage sites in conventionally polished fused-silica flats. This technique can differentiate between surface and subsurface features by changing the illuminating polarization. The method is nondestructive, and no surface preparation is required other than a thorough cleaning of the surface. The intensity distributions in the illuminated region of interest are discussed. The technique has been used successfully as an optical fabrication in-process diagnostic.

Defect formation in hafnium dioxide thin films

Hafnium dioxide thin films were deposited by reactive electron-beam evaporation at six different substrate temperatures on fused-silica substrates. During the depositions, the scattering of light caused by the growth of defects in the films was recorded with in situ total internal reflection microscopy. After deposition the films were analyzed by angle-resolved scatterometery, spectrophotometric measurement of film reflectance and transmittance, atomic force microscopy, and x-ray diffraction. We explore the effects of film defect formation on film optical properties and film surface topography using these data.

INFLUENCE OF CRYSTAL STRUCTURE ON THE LIGHT SCATTER OF ZIRCONIUM OXIDE FILMS

The relationship of light scatter by a thin film to thin-film morphology is examined. Light scatter by reactively evaporated ZrO(2) thin films is analyzed by using in situ total internal reflection microscopy and angle-resolved scatterometry. Film crystal structure is analyzed by transmission electron microscopy and x-ray diffraction. Relations between film crystal structure and film scatter are established by using this information. Surface topography is analyzed by the use of scanning force microscopy. Results of a spectrophotometric determination of the film refractive index are reported. The film scatter is found to be sensitive to the crystal phase of the film, which is a function of substrate deposition temperature. A simple method of separating bulk from surface scatter is described.

Correlation between substrate preparation technique and scatter observed from optical coatings

We present experimental evidence of the dependence of coating scatter on a substrate preparation technique for fused silica substrates. Samples included conventionally polished, superpolished, andfloat-polished substrates. We used scatterometry and total internal reflection microscopy to investigate the effects of substrate preparation on the performance of zirconium oxide thin films. Results indicate that scatter from coatings dominates the scatter signature of the coated optic. They also demonstrate that substrate preparation can affect the level of scatter produced in optical coatings. In addition it is observed that the substrates with the lowest scatter do not necessarily result in the coatings with the lowest scatter.

Contamination of surfaces prior to optical coating by in-situ total internal reflection microscopy

Scatter in thin film optical coatings may arise from a variety of sources. Our previous investigations have used total internal reflection microscopy (TIRM) to monitor scatter site generation during film growth. These studies have reported the effects of substrate cleaning techniques and certain deposition parameters on scatter site generation. The present investigation using TIRM to monitor the coating process has yielded new insight into defect generating mechanisms for films of HfO2 and ZrO2. Of particular interest is surface contamination apparently caused by electrostatic effects. Introduction of high electric potentials in the vacuum chamber has been observed to cause surface contamination prior to deposition, resulting in a significant increase in the number of scatter sites.

Fabrication of optical surfaces with low subsurface damage using a float polishing process

The attempt to eliminate subsurface damage in polished materials is a major objective in optical and semiconductor fabrication. The level of subsurface damage in optical components is proportional to the surface scatter and related to the laser damage threshold of the optic. The float polishing process has been shown to produce surfaces with low subsurface damage on ferrite materials. We have ground samples of rough cut Corning 7940 fused silica using synthetic polycrystalline diamond. These samples were then float polished on a precision machine manufactured by Toyoda Machine Works Limited. Our surfaces were characterized using differential phase interference microscopy, total internal reflection microscopy, and scatterometry. We will describe the fabrication process and report the results of the surface and subsurface characterization.

20 years of graduate optics education at the University of New Mexico

The year 2003 marks the 20th anniversary of introducing interdisciplinary graduate optics education at the University of New Mexico. The Ph.D. program in Optical Sciences has produced over 75 graduates. A new M.S. program in Optical Science and Engineering, introduced in Fall 2002, is rapidly gaining popularity. This paper reviews both programs, focusing on their unique features.

Ion Beam Reduction Of Optical Scatter From Coated Metal Surfaces

Deposition of thin (0.2 - 2.0 μm) metal film on a polished metal substrate changes its scatter characteristic. The light scatter due to high spatial frequency structure is reduced by as much as a factor of ten; total integrated scatter is reduced by as much as a factor of four. The effect is strongly influenced by the deposition mechanism employed, film and substrate materials and film thickness. The effect is most apparent when using simultaneous Ar+ bombardment during film deposition (i.e., ion assisted deposition).