An optical bandpass filter, also known as a bandpass filter or BPF, is an optical device used to pass certain wavelengths of light and block others.
Optical bandpass filters are constructed with metallic layers that reflect some frequencies of light and transmit others.
Bandpass filters are used in applications like fiber optic telecommunications and light detection to separate incoming light from multiple wavelengths into individual components so they can be separately analyzed.
The main features of an optical bandpass filter include its center wavelength, bandwidth, and transmission range.
Optical Bandpass Filter Introduction
An optical bandpass filter (OBPF) or band-rejection optical filter (BROF) is a device, usually made of glass, used to pass only selected wavelengths of light through a process known as filtration.
They are commonly used in fiber optics and laser technology to control transmission properties.
The effect of an OBPF can be thought of as analogous to placing a colored piece of glass in front of an object being viewed; although most wavelengths still get through, certain wavelengths reflect off more than others.
Optical filters come in a wide variety depending on their purpose.
Features and Advantages of an Optical Bandpass Filter
Optical bandpass filters or transmission filters are used to select a single wavelength (or narrow wavelength range) of light to go through.
An optical bandpass filter can be made with a variety of dielectric materials, and they’re often constructed using thin films which are bonded together into an optical glass substrate or housing.
Optical filters are available in many different shapes and sizes depending on how much light needs to be transmitted, how specific wavelengths need to be filtered out, and what technology is used for making them.
There are several applications for these products such as IR cameras, color measurement systems, medical imaging machines, and machine vision technologies.
How to Choose Optical Bandpass Filters?
For example, consider an optical bandpass filter that offers a center wavelength of 1200 nanometers (nm) and a bandwidth of 40 nm.
The first step in choosing such a filter would be to figure out what your application’s requirements are.
In many cases, you’ll need to know the center wavelength of your input signal and how much variance there will be between the minimum and maximum signal levels.
If these two pieces of information are readily available—perhaps through documentation or by contacting technical support at your vendor—then you can purchase filters that will meet those needs.
Applications of Optical Bandpass Filters
Optical bandpass filters are used in many applications such as industrial and medical.
Bandpass optical filters can be used to block out a specific wavelength of light or a range of wavelengths depending on how narrow or wide you want your passband to be.
Optical Filters can also be used to polarize light so that when an optical filter passes through something, all other wavelengths are blocked out.
Optical filters can also control specific frequencies of sound waves and radio waves depending on what types of frequency ranges you would like to block or allow through.
Some common uses for optical filters include screening out UV rays from lasers, blocking certain colored lights from taking pictures, and controlling noise levels in industrial settings.
Other Types of Bandpass Filters
Optical Bandpass Filters come in many different shapes and sizes but are all designed to pass one specific wavelength of light.
Optical Bandpass Filters can be used for purposes other than just signal transmission and reception.
They’re frequently used as holographic combiners and beam splitters, among other uses.
To find out more about other types of Optical Bandpass Filters check out our guide What is an Optical Filter? It’s a great resource for any system designers or integrators interested in learning about how optical filters work!