Stereolithography (SLA) is a 3D printing technology that uses light to selectively cure a photosensitive resin, building objects layer by layer. Over the years, various SLA-related technologies have been developed, each with its own mechanism for curing the resin. Here's a rundown of the different types of SLA printers:

1. Laser SLA:

   • Principle: A UV laser beam is directed by galvanometers (or galvo mirrors) to trace and cure the resin in the desired pattern on each layer.

   • Advantages: High precision and detail.

   • Examples: Formlabs Form series, Peopoly Moai.

2. Digital Light Processing (DLP):

   • Principle: Uses a digital projector screen to flash a single image of each layer across the entire platform at once. Each flash cures a layer of resin.

   • Advantages: Generally faster than laser SLA because it cures an entire layer at once. Can achieve fine details.

   • Examples: Anycubic Photon, Elegoo Mars.

3. Continuous Liquid Interface Production (CLIP):

   • Principle: Introduced by Carbon3D, CLIP involves projecting light through an oxygen-permeable window into the resin. The window allows a thin uncured layer of resin to exist between the object and the window, enabling continuous growth of the object rather than the traditional layer-by-layer approach.

   • Advantages: Faster print speeds because it eliminates the need for the "peel" process between layers. Can produce smoother final parts.

   • Examples: Carbon M2.

4. Masked SLA (MSLA or LCD SLA):

   • Principle: Uses LCD panels with a UV LED backlight. The LCD mask lets UV light through in the shape of the layer, effectively "masking" where the UV light should not cure.

   • Advantages: Combines some benefits of DLP (curing entire layer at once) with potentially cheaper components.

   • Examples: Phrozen Sonic Mini, Anycubic Photon Mono.

5. Pivot SLA:

   • Principle: The build platform tilts or pivots slightly after each layer is cured, reducing the forces and potential suction issues that can occur during the peel process in traditional SLA printing.

   • Advantages: Reduces potential for print failures due to suction or adhesion issues.

   • Examples: Fewer commercial examples, but it's a concept that's been explored by the community.

All of these SLA-related technologies produce parts with high surface finish and detail compared to many FDM/FFF techniques. However, they tend to have smaller build volumes and require more post-processing (cleaning, curing, support removal). The choice between them typically comes down to the specific requirements of a project, such as print speed, detail level, material properties, and budget.