Why Effective Bandwidth Matters

Bandwidth is an essential component to measuring spectral resolution accurately and determining the objective scientific properties of color. Spectrophotometers rely on effective bandwidth measurements to accurately give wavelength readings and assist with product quality assurance, forensic analysis, biochemical testing and more. 

Effective bandwidth allows analysts to measure wavelengths of testing samples by isolating narrow bands of radiation to use as interference filters. Spectrophotography relies on effective bandwidth to test color wavelength objectively. Because radiation cannot isolate single wavelengths from a continuum of sources, a wavelength selector uses nominal wavelength and effective bandwidth to determine the wavelength’s true properties. Effective bandwidth is most easily defined as the width of a sample’s radiation at half of its maximum output. 

Why Is Effective Bandwidth Important?

Without effective bandwidth, spectrophotometers cannot perform accurate measurements. The ideal wavelength selector has a narrow effective bandwidth and a heavy throughput of radiation. With a high radiation throughput, more photons can pass through your wavelength selector and produce a strong signal with little background noise, which is essential for easily reading your spectrophotometric results. By decreasing effective bandwidth, you can improve resolution at the price of increasing background noise. Essentially, larger effective bandwidth gives a smooth and noiseless signal at the expense of sacrificing resolution. 

Which Signal Carries Color Information?

Color information is located on the visible part of the electromagnetic spectrum. The electromagnetic spectrum is based on the molecular and atomic transitions that cause the emission or absorption of photons, leading to a visible effect on color wavelength. A photon’s amplitude, energy, frequency, propagation direction, polarization, phase angle and velocity all directly influence its electromagnetic properties. Spectrophotometers use a photon’s interaction with a sample to gather wavelength information. If a photon does interact with a sample, the spectrophotometer cannot get an accurate electromagnetic reading. 

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How Do Spectrophotometers Use Bandwidth? 

All spectrophotometric equipment requires an energy source to get accurate readings. Spectrophotometers work by taking in light, breaking down its spectral components and digitally determining and signaling a wavelength’s function through a display. The spectrophotometric process relies on bandwidth throughout the following procedure:

  1. Light enters the spectrophotometer through a physical slit-width and is dispersed through a monochromator system.
  2. The instrument separates light into distinct, finite wavelengths using adjacent peaks on a spectral bandwidth scale.
  3. The spectrophotometer improves the image resolution by reducing effective bandwidth.
  4. The spectrophotometer decreases noise at the expense of sacrificing resolution by decreasing effective bandwidth. 

Effective bandwidth is essential for producing high-resolution readings of wavelengths and decreasing noise. 

Browse Spectrophotometry Solutions From HunterLab

At HunterLab, we’ve been on the cutting-edge of spectrophotometry for over 60 years. We understand color measurement is key to indicating color accuracy, product safety and brand integrity. To help your business with this, our spectrophotometry experts develop intricate equipment that delivers spectrophotometric results at the highest degree of accuracy and precision. 

Explore our spectrophotometry solutions or contact us online today to learn how we can help you quantitatively assure the quality of your liquid, powder and solid samples with efficiency and ease.