Optical filters are central to diverse contemporary optical technologies, playing a critical role in various medical, scientific, consumer, and industrial applications.
These devices are designed to selectively reflect, transmit, or block specific wavelengths of light, enabling precise spectral control over a range of settings.
As technology advances, optical filters’ potential grows, particularly in exciting new and emerging applications such as virtual and augmented reality, environmental monitoring, advanced medical imaging, and satellite communications.
Applications of Optical Filters in Modern Technology
Optical filters are integral to techniques used throughout the medical imaging industry, including fluorescence microscopy and optical coherence tomography. These filters improve applications’ capacity to provide detailed images of biological structures and distinguish between different types of tissues.
Optical filters are also employed in environmental monitoring applications and are routinely used in devices designed to analyze atmospheric conditions and detect pollutants.
These filters enable the isolation of specific wavelengths of light, allowing scientists to accurately identify chemical compounds present in the environment—an essential tool for monitoring climate change, analyzing air quality, and more efficiently managing natural resources.
Optical filters are also regularly used in free-space laser optical communications, helping to facilitate data transmission via ground-air, air-air, and satellite networks.
These filters help maintain a signal’s spectral integrity, reducing noise and enabling more rapid, reliable communication. As high-speed internet and data services become increasingly in demand, optical filters’ central role in supporting these infrastructures becomes increasingly important.
Ongoing developments in laser technology also showcase optical filters’ importance, especially in applications involving ultrafast pulsed lasers with pulses in the femtosecond to picosecond range. These lasers are increasingly used in medical procedures, precision machining, and scientific research.
Types of Optical Filters
Multiband Filters
Chroma Technology’s range of multiband filters has been developed to transmit multiple wavelengths while blocking others simultaneously. These filters are key to many applications where high-speed acquisitions are important, including machine vision, fluorescence microscopy, and semiconductor inspection.
Technical Specifications and Applications
Wavelength range: Multiband filters can feature several distinct bands ranging from UV to SWIR, all in the same filter, making the possibilities of these filters almost limitless.
Numbers of bands and bandwidth variation: Chroma Technology regularly manufactures four- and five-band filters, and the company has also demonstrated its capacity to create multiband filters with seven distinct bands.
Optical density (OD) performance: Chroma Technology’s multiband filters can achieve OD6 between passbands, ensuring high precision and minimal crosstalk.
Use Case
A demanding life sciences application required a multiband filter with seven narrow bands ranging from UV to VIS and a long pass for NIR light for sequential laser excitation.
Speed was paramount in this instance, and traditional filter wheels had proven too slow to accommodate the millisecond switching times required. Chroma Technology’s multiband filter offered a static solution, allowing rapid sequential acquisition without moving parts.
Image Credit: Chroma Technology Corp.
Tunable Filters
Chroma Technology’s tunable filters allow users to alter their angle of incidence to dynamically adjust the filter’s transmission band. These filters are especially valuable in multispectral imaging and spectroscopy, where flexibility and precision are particularly needed.
Technical Specifications and Applications
Angle of incidence adjustment: These tunable filters adjust the angle of incidence, prompting a shift in the passband. For example, a 10 nm wide tunable bandpass filter could have a 0 ° AOI center wavelength at 630 nm, shifting this to a center wavelength of 550 nm at 60 ° AOI. This could be performed while maintaining the 10 nm bandwidth, ensuring high transmission and excellent near-band and out-of-band blocking.
Image Credit: Chroma Technology Corp.
Image Credit: Chroma Technology Corp.
Wavelength range: These tunable filters can cover the UV to SWIR wavelengths with a single set of filters.
Precision: Precise angle control is required to ensure accurate wavelength tuning.
Use Case
A customer used Chroma’s tunable filters to offer customizable wavelengths for different applications using a broadband light source. This setup significantly reduced costs and complexity by allowing customers to cover a broad spectral range with fewer filters.
Tristimulus Filters
Chroma Technology’s tristimulus filters are central to the accurate measurement of color in display technology. These filters have been specifically designed to match CIE color-matching functions, a vital tool in calibrating and verifying color accuracy in consumer electronics.
Technical Specifications and Applications
Low f1 prime score: These filters are highly accurate and can achieve less than 1 % deviation from the CIE standard.
Field of view considerations: They are also customizable where required, allowing them to match specific cone angles in various systems.
Use Case
In the display manufacturing industry, these filters support color reproduction on screens, ensuring they meet the highest standards. The precise match to CIE functions contributes to consistent quality across devices by reducing noise and improving the reliability of color measurements.
Image Credit: Chroma Technology Corp.
Mid-Wave Infrared (MWIR) Filters
Chroma Technology’s expanding SWIR and MWIR range has allowed the company to move into new application spaces, including gas analysis and remote sensing. These filters provide steeper slopes, superior transmission, and deeper blocking than many of the company’s competitors.
Technical Specifications and Applications
Wavelength range: These filters offer a precise wavelength range of 3 to 6 µm.
Material adaptation: Silicon or sapphire substrates can improve MWIR performance.
High transmission and blocking: These filters enable precise remote sensing and gas detection applications.
Use Case
Chroma Technology’s MWIR filters are used extensively in environmental monitoring applications due to their ability to distinguish between similar gases, such as CO and CO2. This level of precision is essential in applications such as Earth observation from satellites, where accurate gas differentiation is central to pollution tracking and other climate studies.
Image Credit: Chroma Technology Corp.
Image Credit: Chroma Technology Corp.
Custom Solutions
Chroma Technology’s strength and versatility stem from its capacity to offer custom solutions to accommodate specific customer needs. The company successfully leverages its expertise in precision engineering and thin-film coating to develop filters that meet unique requirements, whether for a specific application environment, wavelength, or angle of incidence.
Chroma Technology’s experts support its customers throughout custom filter development.
Technological Edge
Chroma Technology’s advanced sputter-coating process enables precise deposition for highly accurate filter performance. This is coupled with the company’s broadband monitoring capabilities, which ensures consistent quality throughout the manufacturing process.
Its approach involves working closely with customers, allowing Chroma Technology to understand customers’ challenges and provide solutions that enhance their applications.
This customer-centric approach has led to several innovations that set Chroma Technology apart in the optical filter industry.
Its ongoing advances in optical filter design and manufacturing highlight its commitment to innovation and quality. Chroma Technology can provide solutions to meet the specific and rigorous demands of current applications, whether these involve multiband, tunable, tristimulus, MWIR, or any other type of optical filter.
Acknowledgments
Produced from materials originally authored by Chroma Technology Corp.
This information has been sourced, reviewed, and adapted from materials provided by Chroma Technology Corp.
For more information on this source, please visit Chroma Technology Corp.