An optical coating filter is a device that transmits light of different selective wavelengths, which are usually implemented as plane glass or plastic devices in the optical path which are either dyed in bulk or have interference coatings.
The optical properties of filters are completely described by their frequency response which specifies how the magnitude and phase of each frequency component of an incoming signal are modified by the filter. Filters mostly belong to one of two categories;
- The simplest physically is the absorptive filter
- Then there’s interference or dichroic filters
Optical filters selectively transmit light in a particular range of wavelengths that are colors, while blocking the remainder, they can usually pass only long wavelengths, while these short wavelengths only short pass or band of wavelengths blocking both shorter and longer wavelengths
Now let’s talk about the differences between traditional & Hard-Sputtered Optical Coating
Difference Between Traditional & Hard – Sputtered Optical Coating
Some of the filters like band-pass filters are offered with either coating option, while some components just have one coating type; let’s discuss how these filters are manufactured.
The hard-coated filters are fabricated using state the art advanced plasma reactive sputtering coating platform, which means they end up with hundreds of accurate layers on a single substrate during a single coating run.
The traditional filters are fabricated in three sections each of which determines the particular properties of the filter. One coating determines the essential wavelength, bandwidth, and shape of the curve, while the other two determine the range of blocked wavelengths.
This coating is made by vacuum deposition of very thin layers of a partially reflective compound onto a glass substrate. Beyond understanding how these filter coatings are made, it’s imperative to note the benefits of using one type over another in your required application
The hard-coated optical filters are typically better suited for high humidity environments and tend to have a longer shelf life. They provide deeper blocking, higher transmission, and steeper sloped transmission curves, but also tend to be more expensive.
In contrast, the traditional coated filters are generally able to block wavelengths from x-ray to far-infrared which is an extremely large wavelength range. The Nano-optic offers more plenty of size and wavelength options with traditional coated filters
However, the transmission in the band-pass is lower and the coating is less durable with these filters. If your application is high precision, then hard-coated might be your best option.
But for, standard R&D applications, the traditional filters provide a more cost-effective solution. For more detailed information on optical coating filters, along with their features and wavelengths, contact us today!