3rd Millennium Filters fill the market position of high-performance commodity filters for widespread research and instrumentation applications. The most critical feature of filter design is the transition from blocking to transmission. Precise location of band edges, coupled with steep slopes, allows for optimal transmission of spectral energy. While industry standard filters are defined by Center Wavelength (CWL) and Bandwidth (FWHM), 3rd Millennium filters are specified by the critical cut-on and cut-off edges, resulting in much more accurate band placement and bandwidth. The 3rd

Millenniummanufacturing line incorporates CNC, robotics, and refined process allowing a high degree of consistency.

Improved Environmental Stability
The patented assembly provides an air and moisture-tight barrier for greater longevity. Durability is improved with outer anti-reflective coating per MIL-C-675C.

Improved Filter Life
Traditional filters use organic polymers and other sealants as an environmental barrier. Sealants degrade from exposure to light, water, and oxygen putting protected coatings at risk. Increased filter life in “natural, hot humid environment”; (3) routines of cycle I, per MIL-STD-810E test.

Improved Materials
Soft dielectric coatings deliver the most precise spectral performance, but are limited by protective glass layers and optical epoxies. 3RD Millennium filters use optimal soft dielectrics while eliminating polymeric adhesives, resulting in lower auto-fluorescence, improved transmitted wavefront, and improved heat tolerance. In addition the filter substrates are made of highly purified fused silica.

Reduced Auto-fluorescence
Pure SiO² substrates and the elimination of epoxies greatly reduces auto-fluorescence that often occurs at wavelengths identical to the signal in question. 10e-¹² photon/photon maximum auto-fluorescence.
Improved Transmitted Wavefront
The reliance of fused silica and the elimination of polymers eliminates variable shrinkage during cure—the single largest factor in transmitted wavefront errors. Defraction limited transmitted wavefront distortion; TWD range from ½λ to ¼λ .

Improved Heat Tolerance
The elimination of polymers and the lower coefficient of expansion of SiO² greatly improves the tolerance of filters to high radiant flux, which destroys and degrades epoxies. Tested filters maintained 165°C for more than 2 hours.

Improved Transmission
The removal of epoxies along with the use of highly purified SiO² substrates typically improves transmission by 10%.

Automated Manufacturing
3^rd Millennium filters are produced in custom engineered coating equipment that progresses from raw material to complete assemblies in a shortened manufacturing cycle. The coating chamber is load-locked so that it remains under stable high vacuum conditions between coating cycles.

Increased Yield & Uniformity
Control and design of manufacturing processes leads to yield and product uniformity.

Shortened Lead Times
Short manufacturing cycles result in controlled inventories and shorter lead times.

Alpha Technology
3^rd Millennium filters are manufactured using Omega Optical's proprietary ALPHA Technology, a process which produces exceptionally steep cut-on and cut-off slopes. This results in more precise location of cut-on and cut-off points, the ability to place transmission and rejection regions extremely close together, and higher attenuation between the passband and the rejection bands.

Minimized Coatings
Bandpass filters are made using a combination of an ALPHA longpass (cut-on) and ALPHA shortpass (cut-off) component. Longpass and shortpass filters are each made using a single coating.

Reduced Multiple Images
No more than two coatings are used in each filter— the cut-on and cut-off. Reducing the number of coated surfaces minimizes multiple images. Multiple images result from residual reflectivity of multiple coated surfaces.

Higher Throughput & Attenuation
3^rd Millennium stock filters have ALPHA slopes which are 10 times steeper than industry standard Fabry-Perot designs. As a result, passbands can be made wider and still achieve the blocking requirements of narrower, less steep designs. For example, a 20nm bandpass 3RD Millennium filter has 200% higher throughput, as well as better spectral purity at OD4, than a 10nm Fabry Perot industry standard bandpass filter. In other words, wider 3RD Millennium bandpass filters outperform narrower standard designs by providing improved transmission, better blocking, and higher signal-to-noise.