Infrared (IR) bandpass and dual band filters
Featured Product from Alluxa, Inc.
Precision Infrared Narrow Bandpass and Dual Bandpass Filters Featuring Low OH-Band Absorption
Alluxa’s new precision infrared bandpass and dual bandpass filter technology brings new levels of performance with higher transmissions, steeper slopes, and flatter pass bands than traditional evaporated coatings.
Alluxa’s new class of Infrared (IR) bandpass and dual band filters bring the precision of dielectric filters to the IR between 2 and 5 microns. They are manufactured with an advanced, plasma enhanced PVD process using durable, hard metal-oxide, and durable semiconductor front surface thin films. The films have excellent environmental stability. The OH (water) band at 2.7 microns shows loss below the measurement limit even after 10 days of harsh Mil-810G temperature and humidity cycling.
Applications
The narrowband and dual band IR filters are the latest innovation in the Ultra product line to come from Alluxa’s novel plasma hard coating process. The filters will offer performance improvements and new design options in a wide range of applications from gas sensing, chemical monitoring, and night vision, to LIDAR and FTIR Spectroscopy.
Bandpass Filter Review
Resonant cavity bandpass filters’ basic design principles are well known and relatively simple. The filters are composed of stacked, resonant Fabry-Perot cavities where quarter-wave stack reflectors are spaced apart by a cavity layer. An excellent book describing the subject further is “Thin Film Optical Filters” by Dr. Angus Macleod. Designing filters to have improved squareness, or steeper slopes, is a relatively straightforward matter of increasing the number of cavities in the filter design. To make a filter narrower, the designer increases the optical thickness of the spacer layer or increases the reflectivity of the quarter-wave stack mirrors. This is analogous to increasing the finesse in any other resonant cavity.
An alternative design approach commonly used in this industry is to combine a Long Wave Pass filter (LWP) with a Short Wave Pass filter (SWP). This design approach is favored for wider filters, and for filters which may have asymmetric slope requirements. Slopes can be increased by simply adding layers to the LWP or the SWP.
Adding cavities to the resonant cavity or layers to the edge filters challenges the deposition process control system, and invariably introduces undesirable ripple and loss to the pass band of the filter. Alluxa has created a new low noise IR optical monitoring system that provides the utmost in layer thickness control, which enables significantly more cavities and layers to be added to designs that are still practical to manufacture. The novel, advanced computer control system constantly measures the filter function and compensates for thickness errors associated....more....
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INNOVATIVE ENGINEERING
Advanced plasma deposition. Precision wavelength control. New metrology techniques. Learn how our thin-film coating technology has enabled the routine production of optical components with performance and prices that were previously impossible. learn more...
Learning Center
Our technology enables the routine production of optical filters with performance and price characteristics that were previously impossible. These informative white papers help our customers and partners maximize the advantage they gain by using our filters.
Why Alluxa
Alluxa is an ISO 9001:2015 certified, ITAR registered manufacturer of high-performance optical filters and thin-film coatings. Alluxa has rapidly grown from a small startup to a world leader in precision thin films. Our engineering team has been instrumental in achieving this growth by refining our advanced SIRRUS™ Plasma Deposition process, designing and building our coating equipment, and dedicating a large amount of resources to research and development. Meanwhile, our leadership team has been reinvesting in the business and creating a progressive company culture that benefits both our customers and our people.
