All resin 3D printers belong to the same process family, vat photopolymerization: light hardens liquid photopolymer one layer at a time. What differs is how the light reaches the resin. Laser SLA draws each layer with a moving spot. DLP projects a whole layer at once from a chip of tiny mirrors. Masked SLA, usually called MSLA or LCD printing, shines an LED array through an LCD screen that blocks the light everywhere except the shape of the layer.
Those differences decide what limits detail, how print time changes with the number of parts, how large the build area can be, and what wears out. Specifications are easy to misread, because a laser's spot size, a projector's resolution and an LCD's pixel count are not directly comparable. This page explains each light engine and then compares them side by side.
Laser SLA: tracing each layer
In laser SLA, a laser spot moves across the resin to trace each cross-section. Loughborough University's Additive Manufacturing Research Group describes motor-controlled mirrors steering the beam, and Formlabs lists the laser's spot size, its power distribution and the precision of the galvanometer mirrors among the factors that set XY resolution, along with layer height.
Spot size is not the same as XY resolution. Formlabs cites its Form 3+ as having an 85-micron laser spot but a 25-micron XY resolution, because the laser can be positioned in steps finer than its own width. Since the laser draws point by point, time per layer grows with the area being cured. Prusa notes that adding more objects lengthens an SLA print, and TI's comparison rates point-by-point laser SLA as slower than whole-layer exposure. Formlabs says laser SLA keeps pace with DLP and LCD for small parts but is slower for medium to large parts or full batches.
DLP: projecting a whole layer
A DLP printer uses a digital micromirror device (DMD), a chip covered in microscopic mirrors that each tilt to send light toward the resin or away from it. Texas Instruments, which makes DMDs, says each layer is exposed with a single pattern, so build speed does not depend on the layer's complexity or the number of parts. TI lists micromirror sizes of 7, 10 and 13 µm and 3D printing chips ranging from 1024 × 768 to 2716 × 1600 mirrors.
Each mirror becomes one pixel on the resin, and projection optics scale the image to the build area. The pixel size on the resin is therefore roughly the image width divided by the number of mirrors across it. As a worked example, a 1080p chip has 1,920 mirrors across: spread over a 96 mm wide image, each pixel is 50 µm, and over 192 mm it is 100 µm. Formlabs makes the same point, saying DLP resolution falls as the build area grows, and puts typical desktop DLP XY resolution at about 35 to 100 microns. It also notes that pixels can distort toward the edges of the image, which are farther from the light source.
MSLA: masking an LED array with an LCD
An MSLA printer places an LCD panel directly under the resin tank, with an array of UV LEDs below it. The LCD displays the layer's cross-section: light passes through clear pixels and is blocked by dark ones. Prusa's SL1S works this way and uses a 5.96-inch monochrome LCD with 2560 × 1620 pixels over a 127 × 80 mm build area, which works out to roughly 50 µm per pixel. Formlabs says its Form 4 also uses a masked LCD and cites a custom 50 µm pixel.
Because the mask sits right against the resin, the LCD's pixel pitch sets XY resolution directly, and it does not change with distance as a projected pixel does. A larger build area needs a larger panel with more pixels and more LEDs, which Formlabs says raises cost but keeps resolution the same. Light quality matters too: Formlabs lists collimation and uniformity among the resolution factors, and Prusa's SL1S development notes describe adding a lens assembly to make the LED light more parallel and even.
Light transmission and wear
LCDs absorb most of the UV light that reaches them. In Prusa's development notes for the SL1S, the older color (RGB) LCD passed about 1 percent of the UV light, while the monochrome panel that replaced it passed about 5 percent. Together with new optics, that cut exposure from about 7 to 8 seconds per layer to 1.4 seconds. Formlabs adds that smaller pixels transmit less light, which lowers print speed.
LCD panels are treated as replaceable parts. Formlabs says the generic screens in many low-cost printers have short lifetimes, and rates its own replaceable light processing unit at 600,000 to 1,900,000 layers. TI's comparison lists efficiency loss over time as the MSLA maintenance issue, galvanometer and lens wear for laser SLA, and no print head mechanism for DLP. Formlabs, Prusa and TI each sell one or more of these technologies, so read their comparisons with that in mind.
Side-by-side comparison
Z resolution, the layer height, is set separately by the platform's movement and is similar across the three engines. Formlabs gives 25 to 200 microns as typical for most resin printers, and Prusa lists 0.025 to 0.1 mm for the SL1S. Formlabs also notes that older DLP and LCD printers showed stepped voxel lines on curved surfaces, and that anti-aliasing and finer pixels have largely reduced them.
| Factor | Laser SLA | DLP | MSLA or LCD |
|---|---|---|---|
| How a layer is cured | A laser spot traces the cross-section | A projector flashes the whole layer | An LED array shines through an LCD mask |
| What sets XY resolution | Spot size and beam positioning | Mirror count across the projected image | LCD pixel pitch and light collimation |
| Effect of a bigger build area | The same laser covers more area | Pixels grow unless a higher-resolution chip is used | Needs a bigger panel; pixel size can stay the same |
| Time per layer | Grows with cured area and part count | About constant | About constant |
| Pixel stepping | No pixel grid | Possible; reduced by anti-aliasing | Possible; reduced by anti-aliasing |
| Main wear item | Galvanometers and optics | Little to wear in the light engine, per TI | LCD loses transmission over time |
| Typical uses in TI's comparison | Jewelry, dental, prototyping | Industrial and prototyping | Entry level and prototyping |
Choosing between them
MSLA is the cheapest way into resin printing. Formlabs puts low-cost LCD printers at about $200 to $1,000 and professional resin printers of all three types at about $2,500 to $10,000, while warning that cheap machines may need calibration for each resin. If you buy one, budget for replacement screens and tanks, and use resin profiles tested on your machine.
Laser SLA keeps its detail regardless of build size and has no pixel grid, but slows down as you fill the plate. DLP gives fast, constant layer times and a durable light engine, but resolution and build size pull against each other unless you pay for a higher-resolution chip. For all three, published XY numbers are only part of the story. Formlabs notes that peel forces, resin temperature and calibration also affect accuracy, and calls resolution often just a vanity metric.
At a glance
Strengths
- Laser SLA: no pixel grid, and detail that does not depend on build size
- DLP: whole-layer exposure from a durable micromirror light engine
- MSLA: lowest hardware cost, with layer time that stays constant as the plate fills
Limitations
- Laser SLA: slower as more parts are added to the build
- DLP: pixels grow as the projected build area grows
- MSLA: LCD panels pass little UV and need periodic replacement
Typical applications
- Laser SLA: jewelry, dental and prototyping work, per TI
- DLP: industrial and prototyping systems
- MSLA: entry-level printers and prototyping
Materials for this process
- General-purpose photopolymer resin
- Engineering photopolymer resin
- Castable resin / wax resin
- Dental resins
Common questions
Is MSLA the same as LCD printing?
Usually, yes. Formlabs explains that MSLA can describe any masked stereolithography process but in practice almost always means an LCD mask over an LED array. Prusa describes its SL1S as an MSLA printer that uses a monochrome LCD and UV LED array.
Which type has the best resolution?
There is no single winner. A laser's XY resolution depends on spot size and positioning, a DLP printer's on how many mirrors cover the build area, and an MSLA printer's on its LCD pixel pitch. Formlabs warns that resolution figures are often a vanity metric and that peel forces, calibration and resin behavior matter as much.
Why does a DLP printer's resolution depend on build size?
The micromirror chip has a fixed number of mirrors, and each one becomes a pixel on the resin. Spreading the image over a larger area makes every pixel larger. A 1080p chip spread across 96 mm gives about 50 µm pixels; across 192 mm, about 100 µm.
Do LCD screens in resin printers need replacing?
Yes, over time. Formlabs says many low-cost LCD printers use generic screens with short lifetimes and rates its own replaceable unit at 600,000 to 1,900,000 layers. TI lists efficiency loss over time as the main MSLA maintenance issue. Check the manufacturer's rating and replacement cost before buying.
Sources
- Guide to Resin 3D Printers: SLA vs. DLP vs. MSLA vs. LCD Formlabs · Checked 2026-11-02
- TI DLP Technology for 3D Printing (DLPT019F, revised August 2025) Texas Instruments · Checked 2026-11-02
- Types of printers and their differences Prusa Research · Checked 2026-11-02
- Original Prusa SL1S SPEED 3D printer Prusa Research · Checked 2026-11-02
- Original Prusa SL1S SPEED Dev Diary: How we developed the fastest desktop SLA 3D printer Prusa Research · Checked 2026-11-02
- VAT Photopolymerisation Loughborough University Additive Manufacturing Research Group · Checked 2026-11-02
- Guide to Stereolithography (SLA) 3D Printing Formlabs · Checked 2026-10-15
An explainer synthesized from the cited references, not hands-on testing. Vendor names for processes are trademarks of their owners and are mapped to the ISO/ASTM 52900 families for orientation.