Alfa Chemistry provides a large selection of custom infrared (IR) filters with wavelengths ranging from 1 to 100 µm. By taking into account all design elements, including specs, price, and delivery time, we offer the optimum IR filter solution. Our highly qualified personnel thoroughly inspect each unique product in our cutting-edge metrology lab to make sure that every component satisfies our exacting requirements. To find out more about your demands for a custom IR filter, please get in touch with our technical sales team.
Customized Service
Alfa Chemistry is able to design and produce IR filters to fulfill unique customer needs. The design of thin film coatings, substrate manufacturing and coating, inspection, and environmental testing are all carried out internally. Numerous substrates, including as germanium, sapphire, silicon, zinc sulfide, and zinc selenide, are capable of being coated. We can also make items in unique shapes and sizes.
Our custom capabilities include but are not limited to the following:
Custom IR Interference Bandpass Filters
Only a certain wavelength band of a bandpass filter is intended to be transmitted, while the rest of the band is blocked. Infrared materials like germanium, silicon, sapphire, and infrared quartz are typically coated with many thin layers of materials of various thicknesses and refractive indices to create bandpass filters, or depending on the filter used, a bandpass filter with adjustable bandwidth is created by combining a long-wave pass-through IR filter with a short-wave pass-through IR filter.
Custom IR Longpass Filters
These filters are perfect for transmitting over the larger IR band while blocking the shorter UV-VIS wavelengths. These filters typically have a thin film coating on a substrate made of silicon or germanium. At 1.7 µm and 1.2 µm, respectively, they begin transmitting and are already blocking the UV-VIS area.
Custom IR Shortpass Filters
If customers want to transmit the shorter IR wavelengths while blocking some of the longer IR wavelengths, these IR short-pass filters are helpful. The substrate on which the coating will be put can be made of IR materials like silicon, germanium, or sapphire.
Custom IR Neutral Density (ND) filters
Typically, a thin metal layer is vacuum-deposited atop an IR substrate, such as germanium, to create these filters. Linear transmission over a specified wavelength range is the goal of ND filters. IR ND filters typically rise in steps of 0.1 to OD1, then in steps of 1 from OD1 to OD10. OD is defined as a multiple of ten of the logarithm of the transmission. Alfa Chemistry provides unique IR ND filter sets, standalone OD0.1 to OD1 or OD to OD10 sets, and both of them in combination. The band can range from 1-6 µm, which is usually on silicon substrates, or from 8 to 12 µm, which is usually on germanium substrates. To satisfy specific needs, we can also offer different substrates and densities.
Narrow Band Gas Band Filters
This bandpass filter must have a small FWHM and normally blocks at least OD3 in order to be used for gas detection and analysis applications. The center wavelength will correspond to the peak absorption of a specific gas or multiple gases, so it can be detected from the background signal.
Custom IR Semiconductor Filters
These filters are created by covering a semiconductor substrate with an anti-reflection layer and has long-pass filter properties. There is a little gap between the complete valence band and the empty conduction band in intrinsic semiconductors. The conduction band absorbs them when they have enough energy to cross this gap, but when the wavelength matches the energy gap, the photons from the valence band do not have enough energy to cross the conduction band and are transmitted instead. Here is where the rapid transition from transmission to absorption may be seen. The following substances are frequently used as substrates in semiconductor filters: silicon, germanium, indium arsenide, and gallium arsenide.
Fig 1. Infrared filters protect silicon solar cells from breakage. (Ahmed A, et al. 2020)
In our cutting-edge metrology laboratory, our qualified personnel test each product to make sure it complies with requirements. If you need technical advice, please contact our technical team to learn more about our high-quality services.
Reference
- Ahmed A, et al. (2020). "Effect of Using An Infrared Filter on The Performance of A Silicon Solar Cell for An Ultra-High Concentrator Photovoltaic System." Materials Letters. 277: 128332.