Optical Bandpass Filter Interactive Demo

Adjust the center wavelength, FWHM, and light source to see how an optical bandpass filter shapes the output spectrum. The output plot shows the actual filtered light intensity, not normalized, so you can compare the real effect of the filter and source.

An optical bandpass filter only allows light within a certain wavelength range to pass through, blocking all others.

• Center Wavelength: The wavelength at the center of the filter's transmission window (where the filter transmits the most light).
• FWHM (Full Width at Half Maximum): The width of the filter's transmission band, measured between the points where the transmission drops to half its maximum value.

Light Source Differences:
Halogen emits a smooth, broad spectrum similar to a warm blackbody (like an incandescent bulb).
White LED combines a strong blue peak with a broad yellow emission, resulting in a cooler, spiky spectrum.
Sunlight (AM1.5) provides a smooth, broad spectrum across visible and near-infrared, similar to a 5800K blackbody, representing natural daylight.