Lens and Ir Cut Filter – Ir Cut Filter AHN28 48010313 Lens With Icr Mechanical Shutter

Overview

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15 mm

LENS AND IR CUT FILTER – IR CUT FILTER AHN28 48010313 LENS WITH ICR

distance between two connecting screws 15mm

An IR-cut filter is a mechanical shutter that blocks or transmits light in the IR spectrum to provide true color reproduction. Learn how an IR-cut filter works and why your embedded imaging application may need one.

In recent years, day/night video surveillance has moved beyond the traditional application of simply monitoring critical infrastructures. Typically, systems such as CMOS cameras and CCD cameras capture accurate images in daylight. Their sensors can detect near-infrared light that the human eye cannot see. While this is an important feature for night vision recording, infrared light distorts the colors of images recorded during daylight hours.

You will learn how to use the IR-cut filter on your camera modules to ensure excellent image quality in both day and night (low light) conditions.

Before we discuss the IR-cut filter in depth, let's take a quick look at what "infrared" means.

What is infrared?

Infrared (IR) is also known as radiant energy. It is electromagnetic radiation with longer wavelengths than visible light. Normally, the human eye can see light with wavelengths ranging from 320nm to 760nm. IR ranges from 700nm to 1000nm on the electromagnetic spectrum.

It's much more than what a human eye can see – because only NIR cameras can capture images in this wavelength range.

What is an IR-cut filter?

An IR-cut filter is a mechanical filter that blocks or transmits IR, providing a high-quality image with true color reproduction regardless of day or night.

Unlike the human eye, camera sensors can detect IR light outside the visible spectrum range. To make the image more similar to what humans can see, most OEM cameras are equipped with an IR-cut filter that only allows visible light to pass through, thus reflecting unwanted IR.

Below are sample images with and without IR-cut filter:

How does the IR-cut filter work?

Generally, an IR-cut filter is placed between the image sensors and the lens as shown below.

This filter is controlled by a motor or an electromagnet. When the IR filter is turned on during the day, it helps block IR by allowing only visible light to pass through. This process is known as True Day Night (TDN) because it provides true color images during the day and black and white or night vision images at night.

It ensures that image colors are not distorted and creates a true representation of colors as the human eye naturally sees them.

When the IR filter is turned off at night or in low light conditions, it helps IR and other types of light reach the CCD/CMOS sensor. The image sensor also absorbs enough light and the camera switches to black and white mode, which is more sensitive to IR light.

Now, let's discuss the advantages of using an IR-cut filter in detail.

Reasons to use an IR-cut filter

To prevent discoloration

To achieve realistic colors

– Usually, IR light causes color distortion during the day. To solve this problem, an IR-cut filter is used to keep IR light distortion away from the image sensor during the day. When the light falls below a certain level, the filter automatically rotates to allow IR light to hit the image sensor. Also, the camera switches to black and white mode to make the best use of IR light.– The IR-cut filter on a color camera can achieve realistic colors in white light. In general, the color spectrum viewed by the human eye is quite limited compared to the spectrum viewed by a CCD camera. In particular, the difference in sensitivity in the near-IR region of the spectrum is significant. If an IR cut filter is not used, a large amount of infrared light will be emitted, resulting in strange colors.