A method of determining an effective thickness of a material deposited on a surface and optical constants of the deposited material; comprising the steps of: providing an oscillating means having a surface with a surface area, said oscillating means being part of an oscillator circuit such that it is caused to physically vibrate or support resonant or non-resonant acoustic waves when electrical potential is applied thereto; providing a chamber in which a fluid which contains a depositable material is caused to be present as well as said oscillating means; simultaneously or sequentially: allowing said depositable material to deposit onto the surface of said oscillating means before and/or while it is caused to vibrate and/or support resonant or non-resonant acoustic waves at a frequency; and causing a beam of electromagnetic radiation provided by an ellipsometer to interact with said surface area of said oscillating means and then enter a data detector; determining a relationship between a change in the frequency of said oscillating means against the effective thickness of material deposited thereupon, and providing a mathematical ellipsometric model of the oscillating means and deposited material system which includes said effective thickness, and optical constants of the deposited material; analyzing a change in frequency of said oscillating means to determine the effective thickness of said deposited material based on said relationship; and performing regression of the data detector provided data onto said mathematical ellipsometric model to determine optical constants of said deposited material in view of said determined effective thickness. providing an oscillating means having a surface with a surface area, said oscillating means being part of an oscillator circuit such that it is caused to physically vibrate or support resonant or non-resonant acoustic waves when electrical potential is applied thereto; providing a chamber in which a fluid which contains a depositable material is caused to be present as well as said oscillating means; simultaneously or sequentially: allowing said depositable material to deposit onto the surface of said oscillating means before and/or while it is caused to vibrate and/or support resonant or non-resonant acoustic waves at a frequency; and causing a beam of electromagnetic radiation provided by an ellipsometer to interact with said surface area of said oscillating means and then enter a data detector; allowing said depositable material to deposit onto the surface of said oscillating means before and/or while it is caused to vibrate and/or support resonant or non-resonant acoustic waves at a frequency; and causing a beam of electromagnetic radiation provided by an ellipsometer to interact with said surface area of said oscillating means and then enter a data detector; determining a relationship between a change in the frequency of said oscillating means against the effective thickness of material deposited thereupon, and providing a mathematical ellipsometric model of the oscillating means and deposited material system which includes said effective thickness, and optical constants of the deposited material; analyzing a change in frequency of said oscillating means to determine the effective thickness of said deposited material based on said relationship; and performing regression of the data detector provided data onto said mathematical ellipsometric model to determine optical constants of said deposited material in view of said determined effective thickness.