Neutral Density Filter

Neutral Density Filters (ND Filters) are essential precision optical components that absorb or reflect untransmitted light, uniformly reducing light transmittance across a specific spectral range without altering spectral characteristics. They are categorized into two main types based on their working principles: reflective and absorptive ND filters.

Reflective neutral density filters utilize thin-film interference to transmit a portion of light while reflecting the remainder, ensuring stable light attenuation. Absorptive neutral density filters, by contrast, rely on the intrinsic properties of their base materials or elements mixed into the materials to absorb specific wavelengths, with minimal to no impact on other wavelengths. It is important to note that absorptive ND filters typically feature a lower damage threshold and may generate heat during prolonged use, requiring cautious operation in application scenarios.

As key optical components for light flux control, neutral density filters effectively reduce the transmittance of specified spectral wavelengths, thereby lowering light intensity to protect sensitive sensors, electronic components, and other optical parts from damage. Widely applied in laser optics and optoelectronics fields, they play a critical role in optimizing performance for laser systems, imaging equipment, machine vision, and precision optical instruments.