Optical Filters for Machine Vision Applications

Introduction to Machine Vision Filters

In machine vision, optical filters enhance image quality by controlling light wavelengths. Understanding the types and technologies behind filters is key to leveraging their benefits in applications like inspection and imaging.

Colored Glass Filters

Colored glass filters are widely used in machine vision due to their affordability and simplicity. Created by doping glass with elements that alter its absorption and transmission properties, these filters offer:

• Cost-Effectiveness: Lower cost compared to interference filters.
• Angle Stability: No wavelength shift when used with wide-angle lenses.
• Applications: Common in IR cut-off filters to block infrared light, improving color accuracy in color cameras and contrast in monochrome cameras.

However, their broad cut-off bands and lower transmittance limit precision compared to interference filters.

Interference Filters

Coated interference filters provide sharper cut-off transitions, higher transmittance, and better blocking. They are manufactured by depositing dielectric layers on a substrate, creating precise spectral control through constructive and destructive interference. Types include:

• Bandpass Filters: Transmit a specific wavelength range, ideal for imaging applications.
• Longpass Filters: Block shorter wavelengths, transmit longer ones.
• Shortpass Filters: Transmit shorter wavelengths, block longer ones.
• Notch Filters: Block a specific wavelength range, transmit others.

Interference filters excel in applications requiring high precision but may exhibit blue shift with wide-angle lenses due to angle-of-incidence (AOI) effects, impacting wavelength transmission.

Applications in Machine Vision

Optical filters enhance contrast and block unwanted light in machine vision systems:

• IR Cut-Off Filters: Block infrared light to improve image clarity in color and monochrome cameras.
• Color Filters: Boost contrast, as seen in a gel capsule sorting application where a green filter increased contrast from 8.7% to 86.5%.
• Neutral Density (ND) Filters: Control brightness without altering exposure or f-number, ideal for high-intensity applications like welding.
• Polarization Filters: Reduce specular reflections for imaging shiny surfaces.

Why Choose Our Optical Filters?

As a trusted supplier of optical filters, we offer:

• High Precision: Filters with sharp cut-offs and high transmittance for superior performance.
• Custom and Standard Solutions: Stock filters and tailored designs for UV, VIS, NIR, and IR applications.
• Competitive Quality: Matching international standards at cost-effective prices.