Is the larger the scanning range of the field lens, the better? What is the role in scanning?
A lens that works near the focal plane of the objective lens and can effectively reduce the size of the detector is called a field lens. To be precise, the field lens should work on the image plane of the objective lens. On the one hand: the object plane of the field lens coincides with the main plane, and the characteristics of the main plane show that its magnification is 1, so it does not contribute to the magnification of the system; on the other hand, the field lens should project the aperture surface of the objective lens on the eyepiece For the entrance pupil of the single lens, the diaphragm surface is also the exit pupil, which can ensure that the exit light of the objective lens can pass through the eyepiece as much as possible. If used in a scanning system, the detector replaces the entrance pupil of the eyepiece.
According to wavelength: 1064nm field lens (also called YAG field lens), 10.6 micron field lens (also called CO2 field lens), 532nm field lens (also called green light field lens), 355nm field lens (also called ultraviolet field lens).
According to the design concept: f-theta lens and telecentric lens. The cost of telecentric lens is very high. The f-theta lens is mainly used in industrial systems.
Laser scanning
The laser field lens is a necessary accessory for laser marking machine equipment,At the time of purchase, you should pay attention to the marking range, and determine it according to your own needs. The main technical parameters are: working wavelength, entrance pupil, scanning range and focusing spot diameter.
Note: The larger the entrance pupil, the smaller the diameter of the focused spot focused by the focusing lens. Therefore, when special marking is required, we will consider using a field lens with a larger entrance pupil, such as fine marking and galvanometer type welding.
Scanning range: The larger the range that the field lens can scan, the larger the focus spot and the greater the distortion. In addition, to increase the scanning range, the focal length and working distance of the field lens must also be increased. The lengthening of the working distance will inevitably lead to the loss of laser energy. In addition, the diameter of the focused spot is proportional to the focal length, which means that if the scanning range is enlarged, the diameter of the focused spot will increase. If the spot is not small enough, the power density of the laser will drop very quickly, which is not conducive to processing.
Therefore, the user should choose the most suitable field lens according to different processing areas, or spare several field lenses with different scanning ranges.
CO2 Post objective scanning system price
The main functions of the field lens are:
(1) Improve the ability of the edge beam to enter the detector;
(2) In the same main optical system, the additional field lens will reduce the area of the detector. If the same area of the detector is used, the field of view can be enlarged and the incident flux can be increased;
(3) The modulation disc can be placed on the image surface to solve the problem of nowhere to place the modulator;
(4) To homogenize the non-uniform illumination on the photosensitive surface of the detector;
(5) When using a flat field lens, a flat field image surface can be obtained;
(6) In terms of aberration correction, the field curvature and distortion of the system can be compensated.