Light reflected from a non-metallic surface becomes polarized, resulting in specular glare. Common applications that produce glare include smooth surfaces or surfaces covered with grease, oil or liquid. Reduce glare and achieve the best image results by using a polarizing filter over the lens and polarizing film over the light source. MidOpt offers three types of polarizers: “PR/PL” Series Linear Polarizers, “PC” Series Circular Polarizers and “Pi” Series Infrared Polarizers. PR/PL are the most common polarizers used to decrease glare over the 400 to 700 nm wavelength range. PC Polarizers are effective in the 400 to 700 nm wavelength range, popular in photography and recommended when a camera has a light metering or auto-focus function. Pi Polarizers are sophisticated wire grid linear polarizers that decrease glare over the 700 to 1,100 wavelength range.
Optimal glare reduction is achieved when a linear polarizer is orientated to pass only light polarized in the direction perpendicular to the reflected light (the glare). Aside from reducing reflections, polarizers help improve contrast, increase color saturation, allow for evaluation of stress in transparent plastic and glass and can be used in pairs to form a variable neutral density filter.
Original Color Image: PCB with flux on copper leads
Monochromatic Image without Filtering: Copper leads on PCB reflect light, making clear liquid flux detection nearly impossible.
MidOptAfter Filter: Clear flux detection is made possible with polarizer film used over the DCM High Powered Ring Light and a polarizer filter over the GOYO 35mm Lens.
Before: Reflections off of a sealed cap illuminated by ambient light and a white LED light source result in specular glare that renders the cap unreadable.
MidOptAfter: A PR032 Polarizing Filter installed on the lens and PS030 Polarizing Film over the light source greatly reduces specular reflections.
Before: Multiple beer bottles imaged at the same time present dark, specular, cylindrical surfaces that are challenging to image because of their tendency to produce glare no matter how the bottles and lighting may be oriented.
MidOptAfter: Polarizing filters used in tandem over the lens and light source significantly reduce glare from the application lighting. In addition, due to the curvature of the bottle, ambient light also creates glare, so a BP635 Light Red Bandpass filter used together with 625nm red LED lighting effectively eliminates glare completely.
Before: Reflected glare from shiny, curved surfaces affect the performance of the cameras auto-gain feature and interferes with reliable pattern detection.
MidOptAfter: Linear Polarizing Filters on the lens and light source, carefully aligned for maximum glare extinction, completely eliminate specular reflections off of the offending part, thus narrowing the dynamic range.
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Optimal glare reduction is achieved when a linear polarizer is orientated to pass only light polarized in the direction perpendicular to the reflected light (the glare). Aside from reducing reflections, polarizers help improve contrast, increase color saturation, allow for evaluation of stress in transparent plastic and glass and can be used in pairs to form a variable neutral density filter.
