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Stereolithography (SLA) and Digital Light Processing (DLP) are two 3D printing technologies that create parts by curing liquid photopolymer resin. SLA uses an ultraviolet laser to draw each layer's shape, resulting in high-resolution, smooth surfaces. In contrast, DLP projects an entire cross-sectional layer at once, making it faster and more cost-effective. SLA is best suited for applications requiring fine detail.


This article will compare DLP and SLA, focusing on their differences, materials, and printing technologies.


SLA 3D Printing Technology

SLA, which stands for Stereolithography, is the oldest 3D printing technology still in use today. Unlike DLP, an SLA 3D printer use  a laser beam to solidify the polymer. The UV laser in an SLA printer is directed to two galvanometers that guide it to the precise X and Y coordinates needed to outline the model's cross-section. As the UV laser beam moves continuously across the print, it hardens the photopolymer layer by layer. The 3D design is divided into multiple sets of coordinates for each layer, which are then sent to the two galvanometers for accurate tracing.

DLP 3D Printing Technology

Digital Light Processing (DLP) is a 3D printing technology that operates similarly to Stereolithography (SLA), both utilizing photopolymers. However, DLP employs a conventional light source, such as an arc lamp, combined with a liquid crystal display (LCD) panel. During the DLP printing process, a vat of liquid polymer is safely exposed to UV light.

The procedure begins with the 3D model being loaded into the printer. An in-built projector, positioned beneath the resin container, projects slices of the 3D image onto the resin layers. The first layer of the polymer hardens upon exposure to UV light, and this process is repeated for the second and all subsequent layers of the photopolymer. This layer-by-layer exposure continues until the entire 3D model is constructed.

Difference Between SLA and DLP 3D Printing 

Technology and Light Source

  • SLA (Stereolithography):

    • Uses a laser to cure liquid resin.

    • The laser traces the cross-section of the object layer by layer.

    • The laser is a pinpoint light source, which moves in a predetermined path to solidify the resin.

  • DLP (Digital Light Processing):

    • Uses a digital light projector screen to flash a single image of each layer all at once.

    • Each layer is cured in a single flash.

    • The projector shines light across the entire layer, curing the resin in one go.


  • SLA:

    • Generally slower since the laser must trace the entire cross-section of each layer.

    • The speed can be limited by the complexity of the object and the path the laser needs to follow.

  • DLP:

    • Faster because it cures an entire layer at once.

    • The printing speed is usually consistent regardless of the complexity of the object.

SLA 3D Printing

Resolution and Surface Finish

  • SLA:

    • Typically offers slightly better resolution due to the fine point of the laser.

    • Better for detailed and intricate parts where high resolution is crucial.

    • Smoother surface finish, but this can vary based on the quality of the printer and resin.

  • DLP:

    • Offers high resolution, but the pixelation effect (visible layers) can be more apparent compared to SLA.

    • The resolution is defined by the projector’s pixel grid, so it's important to use a high-resolution projector for finer details.

    • Surface finish is usually very good, but may require post-processing to achieve the smoothness comparable to SLA.

Maintenance and Operation

  • SLA:

    • Generally more complex maintenance due to the laser and mirrors which need regular cleaning and calibration.

    • More sensitive to alignment and mechanical issues.

  • DLP:

    • Typically simpler maintenance as it relies on a projector, which is generally easier to maintain.

    • Fewer moving parts compared to SLA printers, potentially leading to fewer mechanical issues.


DLP 3D Printing
  • SLA:

    • Printers can be more expensive due to the precision of the laser components.

    • Resin can also be costly, but there is a wide range of options available.

  • DLP:

    • Generally, printers can be more affordable due to the use of readily available projectors.

    • Resin costs are comparable to those used in SLA printing.


  • SLA:

    • Ideal for applications requiring high detail and precision, such as dental models, jewelry, and highly detailed prototypes.

    • Common in industries where accuracy and fine details are crucial.

  • DLP:

    • Suitable for rapid prototyping, small to medium-sized parts, and applications where speed is more critical than the utmost fine detail.

    • Popular in sectors like consumer goods and functional prototyping.

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