What is polarization?
Polarization refers to the direction of oscillation or vibration of light waves being emitted by a light source. Polarizing filters can filter those vibrations of light so that the oscillations emitting from the filter go only in one direction.
Who makes and manufactures polarization products and optical filters?
American Polarizers, Inc (API) designs and manufactures advanced optical solutions that control, filter, and manage light. Core products include linear and circular polarizers, wave plates, optical filters laminated to film, acrylic, and glass for visible, infrared, ultraviolet, and specialty wavelength applications. Our factory is in Reading, Pennsylvania, USA, and we are ISO 9001:2015, ITAR, and FAA-PMA cerfified.
What does a polarizer do?
A polarizer helps manage properties of light to only allow certain polarization states to pass. Such light manipulations reduce glare, improve extinction and contrast, and make images easier to see. Polarizers are commonly used in displays, sensors, cameras, instruments, and protective eyewear.
What types of polarizers does API offer?
API offers linear polarizers, wave plates, and circular polarizing filters in film, acrylic and glass substrates. Our polarized products can be absorptive, reflective, and wire-grid type linear and circular polarizers in the visible, NIR, SWIR, and UV ranges. They can be cut, shaped, and finished based on what your project requires.
Where are API’s products used?
API’s optics are used in medical devices, imaging equipment, machine vision, industrial equipment, aircraft and aerospace systems, scientific instruments, cameras, 3D systems, displays, and many everyday electronic products.
Can I order custom sizes or shapes?
Yes. API specializes in custom solutions tailored to your wavelength range needs, environmental and durability demands, substrate requirements, and geometry (shape and thickness).
What is the difference between a linear polarizer and a circular polarizer?
A linear polarizer filters light vibrations in one direction, while a circular polarizer, utilizing a linear polarizers and wave plate, converts the emitted light to a rotating polarization state. The right type of product depends on the application. Our engineer and sales team can help you with the right product for your application.
What is a wave plate or retarder?
A wave plate is a thin optical component that changes the way light behaves. It can convert linear polarized light into circularly polarized light (quarter wave) or rotate the polarization state (half wave). This can help control reflected light, clarity, and color accuracy in optical systems — especially in cameras and scientific equipment.
How do I choose the right polarizer for my project?
The best choice depends on your light source, viewing conditions, durability needs, and the type of device or display. API engineers evaluate your system needs, optical performance requirements, and environmental needs to recommend the right material, substrates, and design.
How can I speak with someone about a custom solution?
You can contact API directly through the website (apioptics.com), email (sales@apioptics.com), or by phone (610-373-5177). Our technical team can review your application and help design the best optical solution for your needs.
What is visible linear polarizer film?
A visible linear polarizer film is an optical filter (film, acrylic, or glass) designed to filter visible unpolarized light so that only vibrations (oscillations) in one direction can pass through. It’s called “visible” because it works specifically within the visible light spectrum (roughly 400–700 nm). We also offer IR, SWIR, and UV linear polarizer filters.
What is a linear polarizer with a high extinction ratio?
A linear polarizer with a high extinction ratio allows high amount of light to pass while strongly blocking the unwanted polarization direction. High extinction is a good indicator of a quality linear polarizer, and it provides better glare reduction, improved colors and brightness, higher image quality, and a better optical system contrast. Extinction ratio is calculated as transmission parallel divided by transmission crossed (Tp/(Tc).
Why is extinction ratio important in a linear polarizer?
The extinction ratio determines how effectively the polarizer suppresses unwanted light while allowing a higher amount of the wanted light. The increased contrast means deeper blacks, reduced glare, and better image clarity. API offer a wide range of linear polarizers with excellent contrast ratios.
What does “extinction ratio” mean, and how is it different from “contrast ratio”?
Extinction ratio is a measure of the film’s performance itself and how much light passes along the intended polarization axis compared to the blocked axis. Contrast ratio is more of a term used for the performance of the finished system, of which the polarizer may be just one of many components and factors. The two terms are sometimes used interchangeably, but API likes to use the term extinction ratio instead of contrast ratio, and that is also pretty much an industry standard.
Are high-contrast linear polarizers better for all applications?
Not always. Some applications value higher transmission of the polarizing filter over crossed transmission, hence a lower extinction ratio. Other systems look for very low overall light transmission thus suppressing the extinction ratio. We’ve been in business for over 60 years making polarized filters and have pretty much seen everything. Our experience in the industry is a great asset to our customers
What range is considered a good contrast ratio for a visible-light polarizer?
For most high-performance imaging or scientific applications, an extinction ratio of 9,000:1 and above is considered excellent. We offer many products that go even higher, up to 16,000:1. Note that our published extinction ratio is an average across the effective wavelength of our polarizing filters. Thus, depending on your wavelength needs, our extinction ratios can be even higher. Please download our data sheets to see the whole range.
Note that the extinction ratios on our main product page are calculated in unpolarized light (as opposed to plane polarized light). Please be aware that testing polarized filters in plane polarized light (input polarized light with an axis parallel to the tested linear polarizer) increases the parallel light transmission, thus producing a higher calculated extinction ratio. Most folks in the industry calculate extinction in unpolarized light, not plane polarized light. But, for comparison purposes, our downloadable product data sheets offer both calculations to help with your product comparison in case you are looking at another competitor’s product that has an extinction ratio calculated in plane polarized light. We are friendly and helpful that way.
