Measuring the quality of infrared emitting LEDs can be done through the following steps:

Firstly, we need to prepare some necessary tools and materials, including a digital multimeter, a dry battery, a small resistor (usually between 100 ohms and 1000 ohms), and several wires. Ensure that these tools are reliable and in good working condition to ensure the accuracy of test results.

Next, we can measure the quality of infrared emitting LEDs by following these steps:

1. Check the appearance: Firstly, carefully inspect the appearance of the infrared emitting LED to ensure that it is not damaged, cracked, or otherwise visibly damaged. Meanwhile, confirm that the pins of the LED are not bent or broken.

2. Circuit connection: Set the digital multimeter to diode test mode, then connect the red probe to the positive terminal (long pin) of the infrared emitting LED and the black probe to the negative terminal (short pin). During the connection process, make sure to use a small resistor as a current limiting resistor to prevent excessive current from damaging the LED.

3. Observe the test results: After the circuit is connected, observe the display on the digital multimeter. If the multimeter shows conductivity (usually displayed as a resistance of tens to hundreds of ohms), it indicates that the infrared emitting LED is working properly. If an open circuit (infinite) or short circuit (close to zero ohms) is displayed, it may indicate that the LED is damaged.

4. Replacement test: To further confirm the test results, you can try replacing the tested LED with another known functioning infrared emitting LED. If the circuit works normally after replacement, it can be confirmed that the LED under test is damaged.

In addition to the basic testing methods mentioned above, additional steps can be taken to verify the performance of infrared emitting LEDs. For example, an infrared receiver can be used to detect the infrared signal emitted by the LED to confirm whether it is functioning properly. In addition, parameters such as forward voltage drop (Vf) and forward current (If) of the LED can be measured to further evaluate its performance.

In short, when measuring the quality of infrared emitting LEDs, we need to prepare necessary tools and materials, and follow the correct steps for operation. By observing the test results and performing additional verification steps, we can accurately determine whether the infrared emitting LED is working properly. At the same time, we also need to pay attention to safety precautions to avoid unnecessary losses during the testing process.