What Is Ir Light In Camera?

Infrared Light And Night Vision

• Infrared (IR) light is invisible to the human eye but visible to specialized IR camera sensors.
• IR night vision security cameras use LEDs to bathe their field of view in infrared light.
• IR cameras perceive objects in low-light and pitch-black settings when IR light reflects off surfaces.
• Once the camera perceives objects and surfaces using IR light, it translates its IR perception into the visible range of light for human end users.

In the context of security cameras, infrared (IR) refers to a type of light that is invisible to the naked eye but essential for night vision capabilities. Although invisible to the human eye, IR light can be perceived by IR-capable security cameras. The camera provides night vision by portraying the scene it captures in infrared light using colors that are visible to the human eye. In this way, they enable clear, detailed footage even in complete darkness.

• Cameras, just like people, need light to see at night.
• Lighting plays a critical role in any security system achieving high-quality, reliable images.
• Infra-red light for video surveillance, sometimes referred to simply as ‘IR’, is a form of electromagnetic radiation which is invisible to the human eye.
• Within the electromagnetic spectrum, infra-red waves occur at frequencies above those of microwaves, and just below those of red visible light.
• Although we can’t see it with the human eye, infra-red light is actually all around us.
• All objects in the universe emit some level of IR radiation.
• While it may be invisible to the human eye, video surveillance cameras can detect infra-red light meaning it can be used to help the camera to see at night.

How Cameras Use IR Light

The ability to film in low light conditions or even complete darkness is essential for many CCTV applications. Part of that ability is down to using the right electronics which are sensitive enough to work in low light, the other tool used is infrared or IR lighting.

Infrared light isn’t visible to the human eye but CCTV cameras switch to black and white as light levels fall and can film the IR light spectrum. This means that to the camera it’s like shining a torch. IR has to bounce off something but providing there is a hard surface to reflect the infrared your camera is able to see in the dark.

• Infrared night vision is the foundation of most security cameras today.
• These cameras use small infrared LEDs that emit light invisible to the human eye.
• When light levels drop, the camera’s IR-cut filter automatically switches to night mode, using this invisible light to create a black-and-white image.
• IR night vision is ideal for total darkness because it doesn’t rely on visible light.
• It’s discreet — intruders often won’t realize they’re being recorded.
• However, it can’t display true color, and its range depends heavily on the strength and number of IR LEDs.
• It’s simple, reliable, and cost-effective.
• The tradeoff? No color information.
• That means while you can see shapes clearly, you won’t know the color of a vehicle or the clothes someone is wearing.

Black-And-White Images In Low Light

• IR cameras switch to black and white in low-light conditions to maximize contrast and clarity.
• Black and white imagery is better at distinguishing features in the dark, as it enhances the visibility of objects by reducing the complexity of colors.
• IR – short for infrared - has been relied upon heavily within the video surveillance domain.
• Allows you to capture a night or low-light scene with good resolution of the images – no speckles.
• Offers greater illumination distance and so further coverage than white light LEDs.
• Only captures the scene in shades of grey at night or with less colour definition in low light conditions.
• It is virtually invisible to the human eye.
• This makes it ideal for situations where you don’t want people to know they are being filmed or where it’s not appropriate to light up the scene continuously or intermittently.

IR night vision is essential for security cameras because it enables them to capture clear and detailed footage in complete darkness. Without IR night vision, cameras would be significantly less effective at night, as they would be unable to see anything in dark conditions.

IR Cut Filter

• An IR cut filter in security cameras is a device that blocks infrared light during the day to prevent it from distorting colors in daytime footage.
• At night, the IR cut filter moves aside to allow infrared light from the camera’s LEDs to bounce off objects and return to the camera’s infrared sensor for detailed images.
• The IR cut filter enables IR for night vision while ensuring clear, accurate colors during the day.

Something you might see mentioned is an IR cut filter. This is a mechanical filter that moves in front of the camera lens during the daytime. The filter is designed to improve colour rendition during daylight filming. Electronic adjustments can also be made to the camera to improve colour representation.

• The ambient light level affects IR security cameras by determining when they switch between regular color mode and black-and-white night vision mode.
• When the ambient light falls below a certain threshold, the camera's sensors activate the IR mode, allowing the camera to continue capturing clear footage in reduced lighting and no lighting conditions.

IR Range And Wavelengths

Infrared range. Do not confuse this with the optical range of the camera or the distance at which a camera can record detail. That is determined by the lens. Wider angle lenses will have a shorter optical range, more telephoto lenses a longer range. The IR range is a largely immaterial figure, often made up and is supposed to represent the distance at which the camera’s infrared can be detected. In reality, the ability of a camera is a combination of the lens, how powerful the IR is and how sensitive the electronics are.

• There are two types of IR:
• 1. 850 nanometres is the most commonly used.
• - slightly visible to the human eye, it offers the furthest coverage or distance.
• 2. 940 nanometres.
• - invisible, but it only offers about half the coverage distance.
• - has to be used in certain scenarios where you are not allowed to inhibit sleep or cause accidents by distracting lights….. e.g. rail networks, detention centres and prisons or mental institutions.

• As shown in the image at the beginning of the article, infra-red waves span the electromagnetic spectrum between 700nm and 1mm.
• Within this range, there are generally two wavelengths of IR light which are most commonly used for security applications: 850nm and 940nm.
• 850nm IR is the preferred choice for the majority of CCTV systems.
• Security cameras are most receptive to this wavelength of IR, meaning it can deliver longer distances and provides the camera with the best possible images.
• Sometimes referred to as semi-covert, an 850nm illuminator gives off a slight red glow, but this is only visible up close or when looking directly into the illuminator.
• This is due to the fact that 850nm is lower down the electromagnetic spectrum, closer to visible light wavelengths).
• For the majority of security applications this does not cause an issue.
• 940nm is a fully covert wavelength of IR which does not emit any red glow from the illuminator.
• However, cameras are not as receptive to this wavelength meaning more light is required to achieve a high quality image.

Benefits For Video Surveillance

• Because infra-red light is not visible to the human eye, it provides an ideal solution for covert surveillance.
• It allows the camera to achieve high quality images during night-time when there is little or no ambient light.
• Surveillance can be carried out without the need of additional visible light which could assist an intruder or notify them that they’re being watched.
• Infra-red illumination is also an effective solution for applications where there is a concern for light pollution and the use of visible light may be considered obtrusive.
• Compared to visible light, infra-red has longer wavelengths that can travel through dust and moisture.
• This means the IR can be used to improve image quality compared to using white-light, or relying on ambient light during daylight hours.

Built-In And External IR Lighting

Round-the-clock monitoring is required for most CCTV applications. You can achieve this by installing a day/night IP camera and some form of infrared (IR) lighting to illuminate the scene. This combination enables continuous video surveillance in all lighting conditions, including total darkness.

• When it comes to infrared illumination, there are two choices: internal (built-in) IR or external IR.
• Built-in or internal illumination
• External infrared illumination.

Previously cameras had separate infrared light lamps bolted onto the side of their housings. It made the whole unit very large and industrial looking. In more recent times cameras have been designed with IR lighting built into them. This greatly reduces their overall size and visual impact. It also reduces cost when compared to modular cameras using separate lighting units.

• By purchasing an IR IP camera, the infrared illumination is built in, so there’s no need for additional hardware.
• This also saves time as you will only need to install, configure and power a single unit.
• Overexposure can be an issue when using infrared illumination, which can result in poor-quality, low-light video.
• IP cameras that emit infrared light also produce heat.
• This can attract insects and spiders, which can then reside on the lens and obstruct the camera’s view.
• IR rays reflecting off an insect and back onto the lens can also cause overexposed footage.
• Built-in IR LEDs may produce glare or reflections when a reflective or bright object enters the scene.
• This could cause overexposure, making it difficult to identify objects such as number plates or individuals wearing hi-vis clothing.

• By separating your illuminator and your day/night IP camera, you have full flexibility when it comes to hardware placement.
• This flexibility enables you to tailor a solution to meet your specific requirements and also to potentially illuminate a wider scene than your camera’s default field of view, such as for an IR-sensitive PTZ camera.
• By placing your IR illuminator and network camera apart, insects attracted to infrared light reside away from the lens and IR reflections from them will more rarely occur, reducing the chance of your camera view being obstructed.
• This also helps to improve object detection and classification, decreasing the chance of overexposure and potential false alarms.
• Most IR illuminators on the market today will be supplied with a range of diverging lenses.
• These lenses are used to spread the infrared light and deliver alternative beam angles and illumination distances.
• The wide choice of lenses allows you to select the best lens for your lighting requirements.
• Keep in mind always that the lens with the widest IR spread will have the shortest coverage distance (inverse square law).
• Lens choice makes external IR a very versatile solution.

Installation Practices

• The best practices for installing IR security cameras include choosing locations for placement that provide high, wide, and unobstructed views; avoiding direct placement in front of reflective surfaces to prevent IR glare; regularly cleaning the lens; and ensuring the IR range is sufficient for covering the intended area.
• It's important to avoid reflective surfaces when installing IR security cameras because reflective surfaces can bounce the infrared light back into the camera lens, causing a whiteout effect.
• This glare can obscure the footage, making it difficult to see anything and defeating the purpose of IR night vision.
• When choosing the range of your IR security cameras, consider the size of the area you need to monitor.
• Make sure the IR range of the camera matches or exceeds this area to ensure that the infrared light can illuminate the entire scene.