IRI 1100, IRI 1101, IRI 1400, IRI 4400

IR INDICATOR CARDS

for detection of infrared light

Modern technical communication and storage systems are increasingly utilizing infrared light (remote controls, fiber connections, CD players etc.). This has become possible by semiconductor technology which offers a great variety of suitable IR emitters such as light emitting diodes (LEDs) and laser diodes. Unfortunately, IR light is not perceptible for the human eye. In contrast to ultraviolet light which excites many materials to show fluorescence, IR light is not that easy to detect. Responsible for this fact is the Stokes law for fluorescence which states that the wavelength of the emitted light is always longer than that of the exciting light. For IR light this means: Once IR - ever IR. Nevertheless, today a series of crystalline phosphors are known which allow to visualize IR light without the need for electronic equipment. For the IR indicator cards under consideration, two functional principles are used:

Chargeable IR indicators apply a phosphor which would show visible fluorescence while obeying the Stokes law under blue or ultraviolet excitation. A special additional doping largely suppresses this spontaneous emission; the exciting energy remains stored (charged). Only IR light sets the stored energy free, under by-passing the Stokes law. This is called stimulated emission. This principle is used by the types IRI 1100, 1101, and 1400.

Converting IR indicators are able to transform IR light continuously to visible light. Converting phosphors circumvent the Stokes law by multi-photon processes. Because of the square law dependence of the visible emission on the intensity of the stimulating IR light (assuming two-photon processes) this functional principle is especially advantageous for higher radiation power. The IR indicator card IRI 4400 benefits from this mechanism.

Preparation: Charging the IR indicator card

Expose chargeable IR indicator cards to daylight or fluorescent light prior to use and recharge after IR illumination when visible emission dimishes or after self discharge. The duration necessary for recharging depends on the intensity of the exciting light. Usually charging takes less than a minute. The blue part of the exciting light is most effective. The IRI 4400 needs no charging.

Operation: IR detection

Hold the active area of the IR indicator card as close as possible to the IR source. If IR radiation is present, the active area will show visible emission. To distinguish the IR stimulation from self discharge luminescence, switch IR source on and off. For best visibility shield ambient light.

Which card type for which application?

IRI 1100. Chargeable. Emits orange light when illuminated by IR radiation. Phosphor: (non-radioactive) Strontium Sulfide, doped by Europium and Samarium. Main application: medium IR intensities in darkened rooms (e.g., IR remote controls). Ultrafast response time. High sensitivity near 1000 nm. Useable from about 780 nm to about 1300 nm.

IRI 1101. Similar to IRI 1100, however with improved sensitivity at 1300 nm. Sensor foil: Q-42 from Quantex.

IRI 1400. Chargeable. Emits green light when illuminated by IR radiation. Phosphor: Zinc Sulfide, doped with Copper and Lead. Special property is the very high sensitivity for low IR intensities below about 900 nm when applied in a dark room. Useable from about 780 nm to about 1500 nm. Examples: 880 nm IR-LEDs, far-field of 780 nm laser diodes for CD players. Well suited for application together with laser safety glasses. Because of additional ultraviolet fluorescence also useful as UV indicator.

IRI 4400. Converting. This card needs no charging, it converts IR light continuously to visible green light. Thus, the domain of the IRI 4400 are high power IR emitters. Phosphor: Yttrium-Ytterbium-Erbium compound. Maximum sensitivity near 950 nm. Useable from about 830 nm to about 1100 nm. Application examples: IR-LED LD 242 from Siemens directly at the top edge of the package; focused 830 nm laser light; focused IR part of sunlight; 950 nm remote controls (in darkness). Well suited for application together with laser safety glasses. Because of the square law dependence of the green emission on the intensity of the stimulating IR light, hold the active area of the IR indicator card as close as possible to the IR source.

Caution

To avoid eye damage from laser beams, always use laser safety glasses! Short-wave UV light reduces durability of the indicator card and may injure eyes! Keep card dry and clean. Do not heat above 50°C!

Miscellaneous data

Card dimensions: 85.6 mm x 54 mm x 0.76 mm
Active area: 10 mm x 10 mm
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