Double optical monitoring of dip coating with a time-varying refractive index

Abstract

A brief overview of optical monitoring for vacuum and wet-bench film-deposition processes is presented. Interferometric and polarimetric measurements are combined with regard to simultaneous monitoring of refractive index and physical thickness in real time. Monitoring stability and accuracy are verified during dip coating with a transparent oil standard. This double optical technique is applied to dip coating with a multicomponent zirconyl chloride aqueous solution, whose resulting temporal refractive-index and physical-thickness curves indicate good reproducibility as well as significant sensitivity to changes of film-flow properties during the dip-coating process.

Analysis of dip coating processing parameters by double optical monitoring

“…2, where each interval between successive extremes corresponds to an optical thickness variation of ͞4. This procedure, combined with the refractive-index values provided by polarimetric monitoring [8], allows determination of physical thickness variation values, as shown in the resulting figures that follow.…”

“…For more complex fluids in which both refractive index and physical thickness vary during the process, a combination of polarimetric and interferometric (double optical) monitoring was introduced, and sensitivity of the method to changes in film-formation stages was demonstrated [8]. In the drainage stage, dominated by mass loss and use of a solgel sulfated zirconia colloid (SZC), the film was shown to be practically unaffected by evaporation and to flow as a Newtonian liquid [9].…”

Temporal evolution of sulfated zirconia sol–gel during dip coating: Analysis of mass drainage with time-varying refractive index

“…1a, can be described as follows. In the interferometric arm at normal incidence, the light transmitted by both beam splitters (4,13) is reflected by the sample (9), in which a liquid film is flowing (Fig. 1b), and is captured by the sample detector (11).…”

“…In this work, we return to the sulfated zirconia aqueous colloidal fluid system during dip coating, using a polarimetric approach recently developed for direct measurement of the refractive index in real time [13]. This allows determination of physical thickness variation values from the reflectance interferograms.…”

Spin-coating process evolution and reproducibility for power-law fluids

“…On other hand, interferometric optical monitoring has risen as a powerful and accurate method for real-time and in situ thickness monitoring in dipcoating [8][9][10] and spin-coating [11][12][13][14] processes. In fact, the interferometric monitoring method is able to provide the typical parameters of the power-law fluid [15] with good accuracy and reproducibility.…”