Cosenoidal correction for line lasers (fall-off compensation)
Thanks to special optics, you can place more power at the ends of the laser line than at the center, thus compensating the response of the system for very large fields of view. In this way the sensor / camera will not be oversaturated at any point by the power reflected from the center of the illuminated object, much higher than the power of the ends without the cosenoidal correction.
A typical application is the measurement or monitoring of curved or very reflective surfaces, like train wheels. Railroad tread inspection greatly benefits from this option. As can be seen in the diagram below, the light power of the laser at points A and A' is much higher than that at point B.
The effect of power difference on the surface to be measured increases as the opening angle (α) increases. Cosine correction is especially recommended for large angles.
Together with the special straightness of the laser lines, this correction option is one of the most relevant improvements in machine vision.
Remember that Osela is the only manufacturer of line lasers that polishes the lenses in their factory after coupling them in the laser module, instead of buying them and simply putting them in front of the diode. It is the only manufacturer that can offer the cosine correction (tell us if we are wrong)
In this table you can see a generic recommendation. Of course, if the object to be measured is curved, the compensation must be increased.
Example: compensation 0.56 means that the power in the center of the line is 56% of the power at the ends.
Using this fall-off compensation you will:
- reduce measurement times
- increase the accuracy
- reduce costs (using lower power diodes)
- reduce space needed to be able to use higher angles while maintaining accuracy
Features of cosenoidal correction in line lasers:
- Compensation for large fields of view
- So the profile captured by the sensor appears uniform
- Excellent for curved and highly reflective surfaces
Check the different line and machine vision laser modules: this option is valid in all of them
- StreamLine: OSE-SL the most standard line laser for machine vision 2D and 3D, ø19 mm
- CompactLine: OSE-C: mini laser ø10 mm and legth 50 mm
- StreamLine Pulsed: OSE-P: high power in small StreamLine module (reduced duty cycle)
- High Power, Industrial Laser System: OSE-HP: high power machine vision lasers
- Ultra High Power, Fireline: OSE-UHP: very high power machine vision lasers
You will probably need laser protection goggles when using these lasers. Check our table of available models (different filter and frame) or contact us directly.