An optical bandpass filter is a spectrally selectively transparent component capable of transmitting select wavelengths of light while blocking others. They are fully customisable to varying center wavelengths and bandwidths, enabling their application in a broad range of practical applications including fluorescence spectroscopy, microscopy, and flow cytometry.
Delta Optical Thin Film previously explored the range of optical bandpass filters available from our extensive range of products, but this article will explore the working principles of an optical bandpass filter in more detail:
Defining Optical Bandpass
Optical bandpass filters are defined by their transmitted wavelength range as opposed to the light that the filter attenuates. This transmitted wavelength range can be precisely determined to accurate bandwidths of nanometer (nm) proportions from across much of the wavelength range.
Visible optical bandpass filters operate within the visible spectrum, passing wavelengths between 380 – 780 nm. Ultraviolet optical bandpass filters can eliminate all visible light and near infrared radiation to transmit wavelengths of below 380 nm – while near-infrared filters are passing near-infrared radiation of close to 780 – 2,500 nm.
Each of these is designed to a specific passband, which is determined by the optical filter’s center wavelength, its bandwidth, and its peak transmittance. The center wavelength of an optical bandpass filter is the midpoint of its transmitted wavelengths, while the peak transmittance is the maximum amount of transmitted light. Its bandwidth is the range of wavelengths able to pass through the filter at a transition value of half. These values all determine the accuracy of a filter’s transmission, its attenuation, and its reliability over the course of multiple experiments.
Optical density is also considered an important factor, and Delta Optical Thin Film have been pioneering the application of Ultra-Hard-Coatings (UHC) for optical thin film components. These complex materials are exclusively used for our filters, allowing for the manufacture of optical bandpass filters of improved durability and unparalleled bandpass stability. UHC-optical bandpass filters exhibit exceptional mechanical qualities, withstanding multiple uses with incident light and radiation, with extreme resistances to light intensity, humidity and heat.
Optical Bandpass Filters from Delta Optical Thin Film
Delta Optical Thin Film are innovators in the design and manufacture of robust optical thin film components for a broad range of analysis and research applications. We provide multiple optical bandpass filters, including customized multiband bandpass filters with bespoke dimensions.