Length and angle infrared measurement system - provides trapezium-shaped intensity distribution by angling planar luminescent diode to grating, and specifies condition relating beam width, distance of diode to grating and distance of scanning plane from grating

摘要

For formation of the grating division (T) having a period (g), a plane infrared luminescence diode radiation source (L) with a total width (B) is provided. The trapezoid intensity distribution of the source in the measurement direction (x) has a central region of constant width (b) with trapezoidally-sloping sides. The condition (B+b).z = s.g is fulfilled when s is the distance of the radiation source (L) from the grating division (T), and z is the distance of the scanning plane (A) from the grating division (T). Between the grating division and the radiation source is arranged a condenser (K). The distance of the condenser from the radiation source (L) is equal to the condenser focus (f) and the condition (B+b).z = f.g is fulfilled. USE/ADVANTAGE - Eg for two-dimensional measurement. Reduces or suppresses low-order local harmonics content of local period radiation intensity, whereby ground wave is only reduced to small extent.