Stray Light and Ghosting
Stray light refers to any light that deviates from its intended optical path and contributes to unintended illumination, glare, background signal, or reduced image contrast within an optical system....
Glossary
Sag (Height)
Sag height is the vertical distance from the base of the microlens to its apex, and is directly related to the lens’s curvature and optical power. It is one of the most critical specifications in microlens array design, both from a performance and fabrication standpoint....
Radius of Curvature (RoC)
RoC defines the curvature of the lens surface and is a key factor in determining focal length and optical power. In microlens arrays, this value is commonly used as a design spec and is typically calculated based on a best-fit curve (usually spherical, unless otherwise...
Lens Pitch
Pitch is the center-to-center distance between adjacent microlenses in an array. It is a key geometric parameter in array layout and plays a significant role in determining the optical fill factor—the proportion of the surface that effectively contributes to light manipulation. Importantly, pitch is not generally...
Lens Diameter
Lens diameter refers to the width of each individual microlens. While there's no absolute physical limit to the diameter, practical design boundaries emerge from optical modeling and fabrication constraints. Lower Bound Considerations: When diameters approach ~10 µm, the system transitions from purely refractive behavior to a hybrid...
Focal Length
Focal length is the distance at which incoming parallel rays converge after passing through the microlens. It's governed by both the radius of curvature and the refractive index—but strongly influenced by the sag height. For a fixed diameter and material, increasing sag shortens the focal length,...
Fill Factor and Transition Zones
Each microlens in an array needs to blend smoothly into its neighbor. The transition zone is the boundary where the curvature...
Autofluorescence
Some materials fluoresce under UV or blue excitation, releasing light at longer wavelengths. This autofluorescence creates a non-coherent, unstructured signal, which can contaminate imaging data—particularly in fluorescence microscopy, biosensing, and quantum applications. Common in: Acrylate-based epoxies Lower-grade polymers Minimized in: Optical-grade silicones UV-stabilized polymers Specialty low-fluorescence epoxies Test...