How to Understand XY Resolution in SLA/DLP/LCD 3D Printing?



When it refers to resolution, you may immediately think of televisions, cell phones, tablets and etc. Resolution is closely related to the definition of those electronic products. In 3D printing, resolution is also often mentioned which deeply affects your 3D parts. The two planar 2D dimensions (XY) and the Z dimension make up the so-called resolution in 3D printing. Our next content will focus on XY resolution in SLA/DLP/LCD 3D printing.


What’s XY resolution in SLA/DLP/LCD 3D printing?


XY resolution is measured via microscopic imaging and limited by optics and radical polymerization kinetics. Simply speaking, XY resolution is the number of pixels displayed by a laser spot diameter for SLA laser systems, a projector for DLP systems, an array of LEDs shining through an LCD. To figure out those differences, we should learn about their technologies first.


Different technologies about SLA/DLP/LCD 3D printing


SLA is driven by two mirrors which is known as "galvanometers" or "galvos" (one on the X-axis and one on the Y-axis). The mirrors aim the laser beam quickly across the target print area to cure the resin as it moves along. In order to reproduce a solid object, SLA must slice the entity, layer by layer, into a series of points and lines that are given to the "galvos" as a set of coordinates whose trajectories are tracked by the laser.



DLP uses a digital projector to project individual images of each layer at once across the entire platform. Since the image of each layer is displayed digitally, it is composed of many square pixels.



LCD and DLP are almost the same but with the UV light coming from an array of LEDs shining through an LCD, not a projector. The screen acts as a mask, displaying only the pixels needed for the current layer.



How to calculate the pixel for DLP/LCD?


As XY resolution is fixed for DLP/LCD systems, so there is a equation:


Width / X Axis = Height / Y Axis = Native Pixel Size


If there is a 3D printer with a build area 68mm wide along the X axis. Divide 68mm (the X axis) by 1440 (the LCD width resolution in pixels), this will equal 0.047mm (47µm). And the native pixel size is 47µm.


That means the minimum XY-Axis feature size for this 3D printer is 47 microns. In 3D printing, no factor is more crucial than XY resolution (horizontal resolution or minimum feature size) when considering what matter most to accuracy. XY resolution is the smallest feature the light source can reproduce within a given line or layer. Generally, the lower the value, the better the details. 


XY Resolution: 47µm


XY Resolution: 100µm


XY Resolution: 47µm


XY Resolution: 100µm


So it’s very important to consider the XY resolution on SLA/DLP/LCD 3D printers, as that tells you whether you’re able to print small but finely detailed objects or larger and coarse objects.