How to calculate the illuminance of an Infrared COB LED - lit area?
As a reputable supplier of Infrared COB LEDs, I often encounter inquiries from clients regarding the calculation of illuminance in areas illuminated by our products. Understanding how to calculate the illuminance is crucial for various applications, such as security surveillance, machine vision, and night - vision systems. In this blog post, I will guide you through the process of calculating the illuminance of an area lit by an Infrared COB LED.
Understanding the Basics of Illuminance
Illuminance is defined as the amount of luminous flux incident per unit area. In the context of infrared light, we are dealing with radiant flux rather than luminous flux, as the human eye cannot perceive infrared light. The unit of illuminance for visible light is lux (lx), but for infrared, we typically use watts per square meter (W/m²).
Key Factors Affecting Infrared COB LED Illuminance
Before we dive into the calculation, it's essential to understand the factors that influence the illuminance of an area lit by an Infrared COB LED:
- Luminous Intensity of the LED: The luminous intensity, measured in candelas (cd), indicates the amount of light emitted by the LED in a particular direction. Higher luminous intensity generally results in higher illuminance in the illuminated area. Our Infrared COB LED products are designed to offer high luminous intensity, ensuring efficient illumination.
- Distance from the LED to the Illuminated Surface: The illuminance follows the inverse - square law, which states that the illuminance is inversely proportional to the square of the distance from the light source to the surface. As the distance increases, the illuminance decreases significantly.
- Beam Angle of the LED: The beam angle determines the spread of the light emitted by the LED. A wider beam angle will cover a larger area but may result in lower illuminance per unit area, while a narrower beam angle will concentrate the light in a smaller area, increasing the illuminance in that area.
Calculating the Illuminance of an Infrared COB LED - lit Area
The following steps will guide you through the process of calculating the illuminance:
Step 1: Determine the Luminous Intensity of the Infrared COB LED
The luminous intensity of our Infrared COB LEDs can be found in the product datasheet. For example, let's assume we have a 100W IR LED with a luminous intensity of (I = 1000) cd in the direction of interest.
Step 2: Measure the Distance from the LED to the Illuminated Surface
Use a measuring tape or other appropriate measuring tools to determine the distance (d) between the LED and the surface you want to illuminate. Let's say the distance (d = 5) meters.
Step 3: Apply the Inverse - Square Law
The formula for calculating the illuminance (E) based on the inverse - square law is:
[E=\frac{I}{d^{2}}]
Substitute the values of (I) and (d) into the formula:
[E=\frac{1000}{5^{2}}=\frac{1000}{25}=40\space cd/m^{2}]
However, in the case of infrared light, we need to consider the spectral response and other factors. If the LED has a non - uniform beam pattern, we may need to use more complex methods to calculate the illuminance accurately.
Step 4: Account for the Beam Angle
If the beam angle of the LED is not a narrow, concentrated beam, we need to account for the spread of the light. The illuminance in an area (A) within the beam can be calculated by considering the solid angle (\Omega) subtended by the area (A) at the LED.
The solid angle (\Omega) (in steradians) is given by:
[\Omega=\frac{A}{d^{2}}]
The illuminance (E) on the area (A) is then:
[E = \frac{I\cdot\cos\theta}{\Omega}]
where (\theta) is the angle between the normal to the surface and the direction of the light.
Practical Considerations
In real - world applications, there are several practical considerations that can affect the illuminance calculation:
- Reflections and Absorption: Surfaces in the environment can reflect or absorb infrared light, which can either increase or decrease the illuminance in the area. For example, a highly reflective surface will increase the overall illuminance, while an absorptive surface will reduce it.
- Multiple LEDs: In many applications, multiple Infrared COB LEDs are used to achieve the desired illuminance. In such cases, the illuminance from each LED needs to be calculated separately and then summed up, taking into account the overlapping areas and the relative positions of the LEDs.
Conclusion
Calculating the illuminance of an area lit by an Infrared COB LED is a complex but essential process for ensuring the optimal performance of your infrared lighting system. By understanding the key factors affecting illuminance and following the steps outlined in this blog post, you can accurately calculate the illuminance and make informed decisions when selecting the appropriate Infrared COB LED for your application.
As a leading supplier of IR LED Chip and Infrared COB LEDs, we are committed to providing high - quality products and technical support. If you have any questions about illuminance calculation or need assistance in selecting the right product for your project, please feel free to contact us for procurement and further technical discussions.
References
- "Lighting Handbook: Reference and Application", Illuminating Engineering Society of North America.
- "Optics and Photonics: An Introduction", Vasudevan Lakshminarayanan, Paul E. Arnaud, and S. S. Kuppuswamy.