Laser Optics - ƒ-theta lenses

ƒ-Theta objectives, also known as flat-field objectives or scan objectives, are used in many industries. While standard lenses display the laser beam on a spherical shell, but not on an even field, ƒ-Theta objectives have one major advantage: You can use them to position the laser focus on a level image field, while the focus size remains almost constant. The position of the focus point (image height) is proportional to the scanning angle.