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What is DOE?What are the basic principles of DOE selection?

What is DOE?What are the basic principles of DOE selection?

Mar 24, 2021

Diffractive Optical Element (DOE) is a newly developed Optical Element in recent years.DOE usually uses micro-nano etching technology to form two-dimensional distributed diffraction units. Each diffraction unit can have a specific morphology, refractive index, etc., to fine-regulate the phase distribution of the laser wavefront. After passing through each diffraction unit, the laser diffracts and interferes at a certain distance (usually infinity or the focal plane of the lens), resulting in a specific distribution of light intensity.


DOE Lens


Diffractive optical elements have shown great application potential in the fields of high power laser, laser processing, laser medical treatment, microscopic imaging, lidar, structured light lighting, laser display, and so on. Its advantages mainly lie in:


1) High efficiency. The precise design of the diffraction unit structure can ensure that close to 100% of the laser energy is projected onto the desired pattern, which is much more efficient than the means such as mask.


2) Easy to use. Diffractive optical elements are very small in size and weight and can be used when inserted into the optical path. In most cases, it can be used with standard lens, field lens, microscopic objective lens, etc.


3) Flexibility. The DOE can be customized for different lasers or for different target intensity/phase distributions thanks to the rapid development of micro-nano fabrication technology. At the same time, the DOE applied light path structure is very simple, in use with different lenses, can achieve different geometrical sizes of the spot.


Basic principles of diffractive optical element selection


According to different purposes, DOE can usually be divided into beam shaping, beam splitting, structured light, multi-focus, other special beam generation, and so on. Each category has a different principle, design, and application characteristics. In general, the following principles should be noted before choosing to use DOE components:


1) The beam generated by the diffracted optical element cannot violate the law of light propagation; The specific light intensity distribution can only exist within a certain depth of field. Therefore, in use, the required spot morphology, size, working distance, depth of field, and so on sometimes can not be both, need to make a trade-off;


2) Diffractive optical elements are usually designed according to laser wavelength, beam aperture, beam mode (M2), and near-field intensity distribution, so these parameters should be measured more accurately before selection. Use parameters and design parameters that do not match will lead to poor use effect or even can not be used;


3) Diffracted optical elements are sensitive to the Angle of incident light and need better optical path adjustment accuracy and stability;


4) Most of the diffractive optical elements can precisely control the wavefront phase of the incident laser, so other components in the optical path, such as reflection/transmission lens, lens, etc., should use high precision and low wave difference devices, otherwise it will affect the final effect;


Lens

5) Like the conventional transmission optical elements, according to the requirements of different wavelength and laser intensity, the diffraction optical elements can be made of quartz, glass, gem, plastic and resin, Zinc Selenide, and other infrared materials, but also can be plated antireflection film.


Elite adopts imported glass DOE, and common patterns are available. Through reasonable design schemes, we can provide customers with high-performance DOE laser modules, and at the same time can provide customers with modules that can replace the DOE by themselves. The wavelength range of the module is 405nm-980nm, and other parameters can be customized according to customer requirements.

 

If you need more information of DOE laser module, please contact us, sale@s-laser.com.