How Do You Tell If A Polarizer Is Circular Or Linear?.
How to Tell if a Polarizer Is Circular or Linear: A Comprehensive Guide
Polarizers are optical filters that allow only light waves of a certain polarization to pass through. They are used in a variety of applications, including photography, sunglasses, and LCD displays. There are two main types of polarizers: circular and linear.
What is the difference between a circular and linear polarizer?
A linear polarizer allows only light waves of a specific polarization to pass through, while blocking all other light waves. A circular polarizer is essentially a linear polarizer with an additional layer of material called a quarter waveplate attached. The quarter waveplate converts the linearly polarized light into circularly polarized light.
Why is it important to know whether a polarizer is circular or linear?
Circular polarizers are preferred for use in photography and videography because they are compatible with autofocus and autoexposure systems. Linear polarizers can interfere with these systems, resulting in inaccurate focusing and exposure.
How to tell if a polarizer is circular or linear
There are a few ways to tell if a polarizer is circular or linear:
- Look for markings on the filter. Some polarizers are labeled as either circular or linear.
- Use a second polarizer. If you have a second polarizer, you can use it to test the first polarizer. Hold the two polarizers together and rotate one of them. If the image dims and brightens as you rotate the polarizer, then you have a linear polarizer. If the image does not change, then you have a circular polarizer.
- Look at an LCD display through the polarizer. LCD displays emit linearly polarized light. If you look at an LCD display through a linear polarizer and rotate the polarizer, the image will dim and brighten. If you look at an LCD display through a circular polarizer and rotate the polarizer, the image will not change.
- Look at a reflection in water. Water reflects linearly polarized light. If you look at a reflection in water through a linear polarizer and rotate the polarizer, the reflection will dim and brighten. If you look at a reflection in water through a circular polarizer and rotate the polarizer, the reflection will not change.
Here is a more detailed explanation of each test:
Using a second polarizer
To test a polarizer using a second polarizer, hold the two polarizers together and rotate one of them. If the image dims and brightens as you rotate the polarizer, then you have a linear polarizer. If the image does not change, then you have a circular polarizer.
Looking at an LCD display through the polarizer
To test a polarizer using an LCD display, hold the polarizer up to an LCD display and rotate it. If the image dims and brightens as you rotate the polarizer, then you have a linear polarizer. If the image does not change, then you have a circular polarizer.
Looking at a reflection in water
To test a polarizer using a reflection in water, hold the polarizer up to a reflection in water and rotate it. If the reflection dims and brightens as you rotate the polarizer, then you have a linear polarizer. If the reflection does not change, then you have a circular polarizer.
When to use a circular polarizer
Circular polarizers are the best choice for photography and videography. They are also a good choice for sunglasses because they can reduce glare and improve visibility.
When to use a linear polarizer
Linear polarizers are a good choice for applications where autofocus and autoexposure are not required, such as scientific research and industrial applications.
Conclusion
Understanding the difference between circular and linear polarizers is important for choosing the right polarizer for your needs. Circular polarizers are the best choice for photography and videography, while linear polarizers are a good choice for applications where autofocus and autoexposure are not required.