The application of the Light Emitting Diodes (LED) in optical measurements

At current moment the Light Emitting Diodes (LED have found a great amount of applications in different areas - for location and communication systems, optical information systems, in architecture light decoration and advertising, traffic signals, etc.. In current work we are making attempt to analyze some new possible fields of LED application. Among these may be build in systems of photometry control. Many different optic and optoelectronic systems are in need of such devices, able to operate for a long time in an autonomous regime. LED's and especially optocouples on their base can provide required time stability and spectral characteristics. The main drawback of such elements is the particularity of the emission diagram. In many case it has unpredictable form, but high reliability and very simple design may compensate many of LED's drawbacks. Below are analyzed the optical schemes enabling transformation of the semiconductor crystal in visible and IR ranges into the beams with angular divergence of 2 degrees. From one crystal, having diameter less then I mm was gained the axial light power exceeding 1000 cd and it is possible to form the light sources providing light power up to 50 - 100 W/str. If to take into account that LED have narrow spectral band and high stability of this spectral band, their small dimensions, rather high efficiency, a possibility of intensity modulation by supply current it is very promising to apply these devices for system of buid in control. Such possibility was not realized in full up till now.