Experiment 04 with IR indicators:

Direct detection of 1550 nm LED radiation

This experiment describes the fundamental application of the IR indicator IRI 1400 for testing 1550 nm IR LEDs for optical fiber applications.

Needed equipment

IR source: 1550 nm LED
IR indicator: IRI 1400
UV-A fluorescent lamp (eg bill detector) or daylight source

Safety measures

Shortwave UV radiation decreases the life span of the indicator card and may harm the eyes! Use UV absorbing sun glasses!

Preparation: Charging

Expose the IRI 1400 to daylight or fluorescent light (normal or UV) prior to use (charge). The charging time depends on the intensity of the exciting light. Normally, it takes less than a minute. Important is the blue and UV part of the charge light. Incandescent bulbs are inappropriate because of their high IR level. It would discharge the card simultaneously during charging.

Realization: IR detecting

Hold the active area of the indicator card near the light emitting diode with ambient light shielded or in darkness. If there is IR radiation, the active surface will emit visible green light. As soon as the IR stimulated emission decreases, direct the IR source onto the unused part of the active area or recharge as described above.