Stabilife® optical filters and coatings are manufactured using two patented processes for the deposition of metal oxide thin film optical coatings; Reactive Ion Plating (RIP) and Hybrid Plasma Enhanced Sputtering (HPES). Both processes yield highly dense, thin film coatings with extraordinary hardness, abrasion resistance, and adhesion to the substrate. Our Stabilife® processes were developed by our Corion coating facility where these products are manufactured.
Optical components which directly effect the spectral performance of an optical system, must be able to deliver repeatable and accurate wavelength vs transmission response, regardless of the operating conditions. In some applications, conventionally deposited optical coatings are adequate to meet the required performance parameters. However, for some of the more demanding applications such as fluorescence detection, wavelength stability is absolutely critical to insure dependable results. Stabilife® optical filters and coatings provide the solution for these high accuracy applications.
Film density is a critical factor effecting the spectral stability of an optical coating. Conventionally deposited metal oxide thin film coatings typically exhibit a significantly lower packing density than Stabilife® coatings. This occurs as a result of the intrinsic growth properties of the coating materials when deposited using conventional methods. The film structure tends to be columnar with a significant volume of voids. The presence of these voids is the cause of environmentally induced spectral shift in conventional external coatings. When a film containing voids is exposed to a dry environment, the voids assume the refractive index of air(1.0). When the same film is exposed to a highly humid environment, the voids will assume the refractive index of water(approx. 1.33). The effective refractive index of the film averaged with the refractive index of the voids will vary from a low relative index in the dry condition to a high relative index in the wet condition. These index changes result in elastic wavelength shift which is dependant upon the ambient relative humidity in which the coating is being used. Spectral shifts in the range of 2-5% of wavelength are typical of conventionally deposited metal oxide coatings. Stabilife® coatings have a higher packing density and lower void ratio and are therefore less effected by water absorption. They typically exhibit total wet-to-dry shifts of less than 0.02% of wavelength.
Stabilife® films are typically 5 to 10 times less sensitive to temperature effects than conventional films due to the use of coating materials possessing extremely low coefficients of thermal expansion (CTE) and low temperature coefficients of refractive index(dn/dt). This design feature, coupled with the high film density resulting from the Stabilife® processes, provides the maximum spectral stability available for all types of precision coatings including bandpass, dichroic, edge, notch and polarizer coatings.
Stabilife® thin-film optical coatings are unsurpassed in their ability to resist damage due to handling, extreme irradiation, and adverse environmental conditions. In the most severe applications, such as autoclave immersed nuclear reactor monitoring, Stabilife® filters have demonstrated spectrally stable performance lifetimes exceeding 8,000 hours. Stabilife® filters have been qualified for telecommunications applications per the requirements of Telcordia GR-2883. While most applications are much less demanding than these, the same robust coatings as are required for extreme applications, are routinely supplied for all Stabilife® products. In the course of normal production, Stabilife® films are tested for adhesion using the snap tape test specified in MIL-C-48497, for abrasion resistance using the eraser test specified in MIL-C-675, and for humidity resistance using the aggravated test specified in MIL-STD-810E.
Stabilife® films are produced over the wavelength range from 200nm in the UV to 3 microns in the IR and have been utilized in a variety of applications including:
Electro-optical Systems
Remote sensors, space cameras, detection systems for use in hostile environments, industrial sensors, cameras, comparator systems, optical sorters, optical scanners/readers, defense optical systems, LIDAR
Instruments
Medical and Surgical instruments, Clinical and Laboratory analytical instruments, Industrial and Agricultural analytical instruments and controls
Components
Stand-alone components for research applications, airfield lighting, laser safety eyewear, substrate passivation
Standard Designs
Narrow bandpass filters / ultra-narrow bandpass filters / wide bandpass filters / notch (band-rejection) filters/ dichroic filters (beamsplitters, polarizers, non-polarizing edge filters) / heat rejection filters
Specialty Designs
High efficiency laser mirrors / multiple-line rejection filters / color balancing filters / passivation coatings
Narrow Bandpass Filters
Stabilife® is an effective solution for bandpass filters from 200mm to 2000mm where thermal, environmental and spectral stability is of primary concern. Filter sizes can range from 0.100 inches to over 15 inches. Typical applications include filters for clinical laboratory instrumentation, color matching systems, and fluorescence detection systems.
Ultra-narrow Bandpass Filters
Stabilife® films incorporate materials with low CTE and dn/dt values to provide filters with dramatically increased temperature stability. This quality, along with the low optical loss of the films, combine to yield high transmittance ultra-narrowband filters with bandwidth of 1nm or less that require no active substrate temperature control during operation. Typical applications for ultra-narrow bandpass filters include filters for astronomical observation, point of care clinical chemistry systems, and environmental monitoring systems. Filters as large as 10 inches in diameter can be provided.
Wide Bandpass Filters
Stabilife® wideband filters provide extremely steep spectral slopes, coupled with thermal and environmental stability for applications requiring wide filter acceptance angle and/or wide spectral transmission ranges. Wide bandpass filters are commonly used in fluorescence detection systems.
Dichroic Edge Filters
For applications such as fluorescence spectroscopy, steep-edged dichroic filters with enhanced temperature and environmental stability have been developed using Stabilife® films. Newport’s designs provide the very narrow transition zones necessary for small stokes-shift fluorophores. Paired with Stabilife® excitation and emission filters, Newport provides fluorescence filter sets delivering superior spectral performance, spectral stability, and durability.
Coatings on Plastics and Semiconductors
Using our RIP Stabilife® process, dense metal-oxide films can be deposited at near ambient temperature on a wide variety of temperature-sensitive substrates such as plastics and semiconductor wafers. Anti-reflection, conductive, and mirror coatings have been deposited on plastics such as polycarbonate, acrylic, and CR39®.
Low Loss Laser Mirrors
Historically, high reflector and output coupler inter-cavity optics have been produced by Ion Beam Sputtering (IBS) techniques. Stabilife® coatings provide similar low defect, low loss coatings in a much faster deposition time, with larger load sizes. Stabilife® reflectors are built with reflectivities greater than 99.99% at 632.8 nm (roughly a factor of ten improvement over coatings manufactured by conventional evaporation techniques). Other thin film products currently manufactured using lBS such as low loss thin film waveguides, high density passivation layers, or phase control laser optics are candidates for Stabilife® technology.
Stable UV Filters
Ultraviolet filters manufactured using Stabilife® technology provide improved stability and lifetime over traditional UV bandpass filters by the inclusion of a band-defining component that requires no protection from environmental factors. Excellent Stabilife® film transparency combines with physical stability to improve transmission, wavelength precision, blocking, and of course, filter life. Stabilife® narrow bandpass filters can be provided at wavelengths as low as 200nm.