Infrared wavelengths and applications

Hotopleds photoelectric infrared led light beads products, the wavelength range in the near infrared between 700-1600nm. Infrared ray can be divided into near infrared ray, short wave infrared ray, medium wave infrared ray and far infrared ray according to the wavelength segmentation.

1. Wavelength

This is the primary parameter to consider. The most common LED wavelengths include 660 nm, 850 nm and 940 nm, which are widely applied in remote controls, medical devices, beauty equipment and surveillance systems. Wavelengths above 1000 nm are frequently adopted in industrial scenarios; examples such as 1050 nm, 1300 nm and 1450 nm are mainly used for machine vision and heating applications.

2. Package Size

The package size of an LED chip is correlated with its internal die and power rating. Small dies of around 10 mil are generally used for low-power applications. Corresponding small package holders are matched with these dies, resulting in LED power below 0.2 W, most commonly available as through-hole components.

Larger dies can withstand higher current and voltage while offering a larger light-emitting area, which naturally delivers higher power. Package sizes for high-power infrared LEDs include 2830, 2835, 3535 and 5050, among which the 3535 package is the most prevalent. The 3535 infrared LED features a 3.5×3.5 mm package holder. It can accommodate 42 mil and 45 mil dies, with a single unit reaching an electrical power of up to 3 W, making it a mainstream model for high-power infrared lighting.

3. Electrical Parameters

Taking our 3535 high-power infrared LED as an example, its operating voltage ranges from 1 V to 2 V with a maximum current of 1000 mA, yielding a theoretical electrical power of approximately 3 W. Low-power LEDs operate at currents ranging from several milliamps to tens of milliamps, with power ratings under 0.2 W. Circuit design must strictly follow the datasheet specifications of the infrared LEDs.

4. Photoelectric Conversion Efficiency

Infrared LEDs feature relatively high photoelectric conversion efficiency, typically capped at 50%. This figure varies with wavelength, and exact values shall refer to test data corresponding to each specific wavelength.

5. Other Parameters

Beam Angle

The beam angle refers to the emission angle of light passing through the LED lens. A suitable angle should be selected based on application scenarios and optical design requirements. Common available angles include 120°, 90°, 60° and 30°.

Service Life

Service life is defined as the operating time before the LED luminous output decays to 50% of its initial value under specified environmental conditions, generally rated at 30,000 hours. Excessively high current or voltage will accelerate light degradation.

Heat Dissipation

LEDs often operate in enclosed spaces with suboptimal heat dissipation performance. This factor must be fully addressed when deploying high-power infrared LEDs. Thermal performance can be evaluated via simulation software during design by referencing datasheets. During prototyping, infrared analyzers are used for testing to keep casing temperature, PCB temperature and junction temperature within reasonable ranges.