Microspectrophotometer (MSP) is an advanced optical system. The key difference with typical low cost reflectometer is in its capability to characterize optical properties of thin films over a micron region area. With unique design by Angstrom's professionals, user can enjoy digital imaging capability in Microspectrophotometers (MSP series) by live video, powerful digital editing, measurement tools for reflection, transmission, absorption spectra. Data acquisition only takes milliseconds. Microspectrophotometers have been used in various fields, like in nano fab, forensic, medical, MEMS, MEOMS, biological, chemistry etc...
Microspectrophotometer Working Principle
Microspectrophotometer integrates vision and spectroscopic measurement together. With vision, small area can be identified for measurement. The sampling area size is directly related to optical system's magnification; therefore, the spot size can be changed by user with selecting different objectives. Vision can be done with trinocular eyepiece or digital imaging via live video. Digital imaging processing is plus with using such tool even for geometry measurement.
Similar to reflectometry measurement, a reference or standard (known its reflection) must be used to calibrate light intensity Io. By acquiring signal (IReference) from this reference and known reflection (RReference), Light intensity Io under the same measurement condition can be obtained. By getting signal from sample, RSample is finally obtained over the sampling area.
RSample = ISample / Io
RReference = IReference / Io
RSample = RReference x ISample / IReference
If the film thickness or its optical constants are needed, then a mathematic fitting algorithm is applied to obtain them via an assumed model (Layer Stack).
where m is number of variables in fitting, q is total data points