DOE Positioning Lasers: Optical Properties & Applications

Positioning lasers equipped with so-called "DOE" elements have certain optical characteristics that differ from standard cross-line lasers or line lasers. We would like to briefly explain these differences here. 

DOE stands for "Diffractive Optical Elements". They usually consist of a substrate, typically made of plastic or glass, combined with a holographic structure or coating. The projection patterns that can be created using a DOE are extremely diverse and can also be customized or modified according to customer requirements. Due to their special optical properties, which often affect the focusability of a laser, DOEs are particularly suitable for short-range applications, as the projected line may become slightly blurred at greater distances. Depending on the model, we recommend using them at distances of up to 200 cm.

If line sharpness is not a decisive factor, positioning lasers can also be used over greater distances. In this case, particular attention should be paid to the projection angle of the respective laser, as these angles usually vary between models and cannot be changed. For example, with a positioning laser featuring a "crosshair" pattern, the projected image size increases linearly with distance. Thanks to the adjustable focus, the line sharpness and therefore the overall image sharpness can be adapted to the respective working distance, which offers significant advantages.

Since DOEs are also wavelength-dependent, the projected image size may vary when different laser colors or wavelengths are used. The final image size is therefore determined by the distance between the laser module and the projection surface. The farther the laser is positioned from the target, the larger the projected image becomes. The projection angle, and therefore the relationship between distance and image size, is defined by the DOE and can only be influenced by changing the working distance.