Schlieren masks: square root monomials, sigmoidal functions, and off-axis Gaussians

Area of Science:

• Optical imaging
• Image processing
• Coherent optics

Background:

• Spatial filters are crucial for phase rendering in optical imaging.
• Effective transfer functions simplify the analysis of nonlinear mappings between structures and their images.
• Comparing different spatial filtering techniques requires a standardized analytical approach.

Purpose of the Study:

• To introduce three novel nonconventional Schlieren techniques.
• To analyze the similarities between these new techniques and existing Schlieren methods.
• To demonstrate the utility of the effective transfer function in comparing spatial filters for phase rendering.

Main Methods:

• Development of three nonconventional Schlieren techniques utilizing absorption masks with specific amplitude distributions (square root monomials, sigmoidal functions, off-axis Gaussian functions).
• Application of an effective transfer function to model the nonlinear mapping between input structures and image irradiance.
• Comparative analysis of the proposed masks and other Schlieren techniques using the effective transfer function.

Main Results:

• The effective transfer function provides a convenient method for describing nonlinear mappings in optical imaging.
• The proposed nonconventional Schlieren techniques offer new possibilities for phase rendering.
• Similarities between the novel absorption masks and other Schlieren techniques were successfully analyzed.

Conclusions:

• The effective transfer function is a valuable tool for comparing spatial filters in phase rendering applications.
• The developed nonconventional Schlieren techniques show promise for advanced optical imaging.
• This work advances the understanding and application of Schlieren imaging for transparent structure analysis.