AcWaCo
Leonid Mihaljov
leonid.mihaljov@acwaco.com
2009
2009
Compensation system for environmental errors in positioning systems with laser interferometric feedback
Local variations in the air temperature are unavoidable. They affect the wavelength of light, causing errors in the length measurements made with laser interferometers.
AcWaCo means Acoustic Wavelength Compensation, a method and equipment for determining the refractive index of air along the laser beam path. It works by measuring the speed of sound traveling the laser beam path simultaneously with the length measurement.
The relative effect of a change in the air temperature is about two thousand times stronger on the speed of sound than on the refractive index. Thus AcWaCo detects even the slightest changes to the refractive index and compensates for them, considerably improving the precision of distance measurements made with laser interferometers.
Precise XY-stages for semiconductor industry, maskless lithography systems, flat panel metrology or similar.
Real-time environmental compensation for laser interferometric feedback of positioning systems operating in air. AcWaCo is the only system that compensates for these errors, offering unprecedented precision of real-time length measurements.
Number of axis: 2
Repeatability of positioning: 1 nm (in range 550 mm)
Range, speed of change of distance, and accuracy achievable with AcWaCo – are interdependent. Improvement of one factor may lead to degradation of others. Therefore, before we can say anything about the possible improvement achievable with AcWaCo in your concrete case, we have to know your boundary conditions: range, speed, accuracy and their desired priority.