Fast structured illumination microscopy with reflectance disturbance resistibility and improved accuracy

Area of Science:

• Optical microscopy
• Surface metrology
• Nanotechnology

Background:

• Conventional fast structured illumination microscopy (FSIM) struggles with non-uniform surface reflectivity, limiting its use for heterogeneous materials.
• Environmental fluctuations and material properties can cause reflectivity variations, affecting profile measurement accuracy.
• Existing methods lack robustness for samples with surface heterogeneity.

Purpose of the Study:

• To develop an improved FSIM (IFSIM) configuration for enhanced axial accuracy and suppressed reflectivity disturbances.
• To enable reliable surface profiling of samples with inhomogeneous reflectivity.
• To offer selective control over dynamic range and axial accuracy.

Main Methods:

• Utilized a digital micro-mirror device (DMD) to project sinusoidal patterns onto the sample.
• Employed two charge-coupled devices (CCDs) placed at different axial positions (in, behind, or before the focal plane).
• Developed a new response function by dividing the sum and subtraction of axial modulation response curves (AMRs) from the two CCDs.

Main Results:

• The proposed IFSIM effectively suppresses the influence of inhomogeneous reflectivity.
• Achieved enhanced axial accuracy and a wide dynamic range by controlling detector defocusing.
• Theoretical analysis and experimental results confirmed the method's feasibility.

Conclusions:

• The improved FSIM (IFSIM) offers a robust solution for accurate surface profiling of heterogeneous materials.
• This technique overcomes the limitations of conventional FSIM in the presence of reflectivity variations.
• IFSIM provides a versatile platform for advanced surface metrology applications.