MOPA Madness: The Wizzard of Awes' Full Tutorial on Fauxlographic Laser Engraving
This guide begins with the quickest useful diffraction experiment, then adds measured fauxlographic swatches, and finally combines diffraction gratings with other Rasterizer image styles and per-swatch geometry. The result is often called a fauxlogram: an engraving whose appearance shifts with illumination or viewing direction. It is an angular diffraction effect, not a true wavefront hologram or a reconstruction of a three-dimensional light field.
Understand the result before engraving
A fauxlogram uses fine, directional surface structures to send different wavelengths and intensities toward the viewer as the light, workpiece, or viewing position moves. The apparent colors are therefore not fixed pigments. A result that looks vivid under one directional lamp can look neutral, gold, or nearly invisible under diffuse room lighting.
Rasterizer exposes three increasingly involved routes. Krasnow Color Grating is the fastest all-in-one starting point. Fauxlographic Etching Lab measures the response of your own machine and material before mapping artwork to observed swatches. Krasnow Grating Geometry Style is the advanced, composable route: it can follow a compatible Image Style or be assigned only to selected swatches while the rest remain ordinary vectors.
Prepare a test sample
Use a flat, clean sample of the exact material and surface finish intended for the final work. Record the laser, lens, focus position, extraction, material preparation, and cleaning method. Diffraction is sensitive to groove shape and spacing, so changing the lens, focus, brushed direction, or cleaning can invalidate an otherwise good recipe.
Prepare the LightBurn Material Library
Before changing any descriptions, clone your existing Material Library in LightBurn's Material Library interface. Then browse to the cloned .clb file on your computer and copy it into a separate backup location without altering it. Give the backup a clear name and date so you can always restore the original settings if anything goes wrong.
Keep the backup outside the location you will edit. LightBurn can show cloned libraries with the same or very similar names, making it easy to edit the wrong copy or accidentally overwrite an existing library. Confirm the full file location before making changes. With an untouched backup stored separately, you can experiment without risking the only copy of settings you have already tested.
Load the working clone in LightBurn and edit each entry's Description to match the Rasterizer swatch you want associated with that setting, such as Black, Red, Blue, or White. Rasterizer swatches match artwork by color, so choose the swatch closest to the color that setting actually produces on the material. The Description is the matching key; the displayed LightBurn layer color or an entry name elsewhere in the library is not a substitute.
Review Rasterizer swatches, color matching, and LightBurn layers before renaming the entries if you are unsure which swatch should represent a tested result.
For the ordinary filled MOPA color settings used by Rasterizer, I have had the best combination of engraving quality and time on the laser when Flood Fill is enabled for every color setting. I recommend trying Flood Fill in your working library and comparing it on your own machine and material. This does not change the Fauxlographic setting described next: that diffraction-grating carrier must remain a Cut/Line operation rather than Fill or Offset Fill.
Add an entry whose Description is Fauxlographic. Set this entry to the most iridescent tested setting you have—the setting that produces your strongest repeatable shimmer or color change as the viewing angle or lighting angle moves. Configure it as a LightBurn Cut/Line operation, not Fill or Offset Fill. Additional sublayers, if present, are ignored because diffraction gratings rely on one precise Cut/Line operation. This is the starting setting for the fauxlographic workflows, so do not choose it merely because it makes the darkest, brightest, or cleanest ordinary mark.
The Fauxlographic setting becomes the carrier-setting anchor used by both Krasnow methods, and the entry may use any LightBurn thickness value. If a q-pulse value is absent in the library, Rasterizer preserves that absence instead of inventing the device-specific value LightBurn may display later.
A Labels entry is useful for Fauxlographic Etching Lab identifiers and other generated labels. A Black entry is required when Black should remain a normal engraved layer. Several Rasterizer components expose this behavior through options such as Preserve Black or Preserve Black Outlines. Keep untested template entries disabled and marked UNCONFIGURED. Do not treat placeholder values as laser recipes.
If you do not already have the expected structure, use the Palette Library Generator to create a safe disabled template, then replace only the entries you have physically tested.
Choose upload or saved-palette operation
For a temporary or guest job, select Upload a new LightBurn Material Library on the Rasterizer page, upload the .clb file, and select its material. Rasterizer searches entries at any thickness within the selected material and matches enabled Rasterizer swatches to their exact Descriptions. This route is convenient for a quick experiment, but guest jobs are temporary and their completion links expire.
For a repeatable member workflow, import the library into Swatch Palette Vault as a Color Palette. Review the palette-wide material name, then explicitly assign each setting to its intended official Rasterizer swatch. The saved assignment map is authoritative; a setting left Unassigned is not made available merely because its Description resembles a swatch. The saved palette can then be selected directly on Rasterizer without uploading the library for every job.
Review Material Libraries and Rasterizer and the Swatch Palette Vault guide before relying on a new import.
First method: launch a Krasnow Color Grating test
Begin on Rasterizer with modest, high-contrast artwork and a moderate processing dimension. Select the uploaded library or saved Color Palette, choose its material, and enable only configured swatches. Under Image Style, choose Krasnow Grating. This is the dedicated Krasnow Color Grating abstract filter and is the shortest path from an image to a diffraction-oriented LightBurn project.
Use the default controls for the first proof unless they would exceed your machine limits. Square cells make the structure easiest to inspect. Keep the artwork physically small, use a Patch Size large enough to see the cell pattern in LightBurn, and avoid an extremely small Line Spacing until the machine's usable mark spacing has been established.
Generate the quantized preview to check the source crop, proportions, available colors, and palette assignment. The preview does not simulate the final diffraction color, but it can expose a missing swatch, unwanted background, or poor image crop before server processing begins.
Understand what the Krasnow filter builds
The filter resizes and palette-maps the image, cleans its color regions, and replaces those regions with clipped cells of parallel open paths. Source luminance selects an angle between Angle Minimum and Angle Maximum. Sufficiently saturated source hues, plus the vertical Gradient Top, Gradient Bottom, and Gradient Curve correction, select diffraction carrier layers.
The Fauxlographic setting is cloned to the carrier layers. Frequency remains the anchor frequency, while calculated speed changes the along-path pulse pitch. Speed Spread controls how far those carrier speeds depart from the Fauxlographic anchor. The layer's organizational RGB color does not itself create or predict the observed diffraction color.
Visible Line Spacing is the distance between parallel paths within a cell. Hue Line Spacing Minimum and Maximum can vary that visible density across approximate wavelength order. These controls are different from microscopic pulse pitch, which is created by speed divided by frequency along each path.
Tune the first Krasnow proof
Change one family of controls at a time. Patch Size changes the physical cell scale: smaller cells retain more local image variation but create more geometry; larger cells average more source pixels and make the pattern coarser. Cell Shape changes packing and silhouette. Square, Hexagon, Triangle, Diamond / Rhombus, and Puzzle Piece are gap-free layouts, while the decorative staggered shapes intentionally expose substrate.
If the grating is too faint, first verify focus and the base Fauxlographic recipe, then test visible line spacing and physical cell size. If hue placement is wrong, adjust Hue Rotation and the vertical gradient controls in small steps. If neutral or pale areas are being pushed into a hue family, raise Saturation Cutoff so more low-saturation pixels use only the correction ramp.
Preserve Black keeps source Black as ordinary closed geometry using the Black setting. Turn it off when Black should become grating geometry and use a clone of the Fauxlographic setting like the other carrier layers. In either mode, inspect the project for unintended backing geometry before engraving.
Before sending the proof to the laser, review the LightBurn settings you provided and confirm they are appropriate for your machine. Use appropriate guarding and extraction, and never leave the laser unattended.
Judge the first engraving
For meaningful comparisons, use a repeatable viewing arrangement. A small, directional white light usually reveals angular color more clearly than broad diffuse lighting. Mark or photograph the positions of the lamp, sample, and viewer, then use the same left, center, and right positions when comparing parameter changes.
Inspect the result under the controlled lamp from left, center, and right. A successful first proof does not need perfect screen-matched color. It should show repeatable directional or iridescent change, preserve recognizable large features, and avoid large regions where multiple settings engraved the same area.
If the result changes only when the lamp moves, that is still a valid angular diffraction response. If no directional change is visible, do not solve the problem by scaling directly to a large artwork. Return to the Fauxlographic base setting, focus, spacing, and physical observation setup.
Go deeper: generate a Fauxlographic Etching Lab grid
Use Fauxlographic Etching Lab when you want measured swatches from your own laser and material rather than a purely calculated Krasnow carrier progression. Select the tested Material Library and material, choose the Fauxlographic entry containing your most iridescent tested setting as the calibration setting, and choose the Labels setting. Define a controlled interval-and-angle sweep and generate the calibration SVG and LightBurn project.
Do not expect this grid to look like a normal image or an orderly chart of predetermined colors. It may initially look strange, fragmented, or unintelligible, with shimmering squares that change as you move the workpiece, change your viewing angle, or move the light. That behavior is expected and is evidence that the grid is exploring different optical responses—not evidence that the process failed.
An individual square is not required to look like a particular named color. The goal is to reveal as many visibly distinct and repeatable square appearances as possible across the tested angle and interval combinations. Differences in hue, brightness, reflectivity, shimmer, and viewing- or lighting-angle response can all make a cell useful.
After the grid is photographed and analyzed, Rasterizer records the observed appearance of each trusted cell together with the geometry and laser setting that produced it. Fauxlographic Artwork uses those measured cells collectively as a palette: it maps artwork colors to the closest observed swatches and applies their corresponding calibrated treatments. The combined result is another style of fauxlogram built from the appearances your own laser and material actually produced.
Engrave the grid without resizing it. Keep the material orientation, focus, lens, surface preparation, and base setting identical to the conditions intended for the final artwork. The Labels setting engraves the identifier and grid labels; it should be legible without overwhelming nearby calibration cells.
A calibration cell records a requested geometry and recipe, not a guarantee that the physical groove exactly equals the requested interval.
Photograph and analyze the calibration
Place the engraved grid in the same controlled lighting and viewing geometry chosen earlier. Avoid automatic white-balance changes between photographs when possible. Fill the frame with the grid, keep it square to the camera, and avoid glare that clips useful colors to white.
Load the photo and its calibration metadata in Fauxlographic Etching Lab. Align the grid overlay to the engraved cells before sampling. The overlay is a guide and is not baked into the sampled image. Review the measured colors and reject dirty, damaged, poorly aligned cells, or cells with no apparent visual difference from others, instead of saving every detected value.
Save the trusted cells as a Fauxlographic Palette when signed in, or download the self-contained Fauxlographic Swatch Palette JSON as a guest. The palette stores observed color together with the cell's interval, angle, and copied laser setting, so it remains specific to this physical setup.
Create artwork with the measured Fauxlographic Palette
Return to Rasterizer and select the saved Fauxlographic Palette, or choose Upload Fauxlographic Swatch Palette and provide the downloaded JSON. Upload the artwork and enable the measured fauxlographic swatches that should be available. Rasterizer quantizes the artwork directly to their observed colors and places each region on a layer carrying that swatch's embedded setting, interval, and angle.
Choose the Cut Mode behavior and decide whether to Preserve Black Outlines when the palette includes a Black setting. Fauxlographic Artwork does not expose ordinary Image Style or Geometry Style controls because the measured swatches themselves define the specialized output treatment.
This method is best when you want the image mapped to colors you actually observed in one controlled setup. It can be less portable than the Krasnow filter because changing illumination, material, focus, or viewing position changes what those measured RGB samples mean.
Advanced method: reveal Krasnow Grating Geometry Style
Choose Krasnow Grating under Geometry Style when diffraction should be a reusable final-geometry treatment rather than the dedicated Image Style. With No geometric effect as Image Style, it provides the closest comparison to the dedicated Krasnow filter. With Cartoon, Color Photo, Structure Tensor Flow, or another compatible style, that stage transforms and separates the source first; Krasnow then rebuilds the resulting regions as grating cells.
The shared Krasnow settings use the same Fauxlographic carrier anchor and the same Patch Size, cell shape, angle, spacing, hue, gradient, saturation, and Speed Spread concepts as the dedicated filter. The important difference is pipeline position: Image Style prepares the geometry first, and Geometry Style transforms that prepared geometry afterward. Start with Fauxlogram Gradient Scope set to Entire Artwork and Direction set to Top to Bottom for behavior closest to the dedicated filter.
For a more spatial effect, choose Each Shape to restart the gradient inside every disconnected prepared component. Choose Left to Right or Right to Left for a horizontal progression, or Center to Edge or Edge to Center for a radial progression. Entire Artwork radial uses the center and bounds of the complete prepared artwork; Each Shape radial uses the center and bounds of each component. Fauxlogram Gradient Start, End, and Curve control the carrier-selection progression, while Angle Minimum and Maximum continue to control the physical direction of the grating lines.
Specialized Image Styles that already create final geometry, including Halftone Newsprint, Optical Color Mix, and the dedicated Krasnow Grating filter, cannot receive a second Geometry Style transformation.
Paint local gradients with Fauxlogram Flow Painter
When Krasnow Grating is the Geometry Style, open Fauxlogram Flow Painter to override the shared gradient inside selected areas. Paint with the translucent region color, use Erase to remove painted control, and drag the Guide across the artwork to establish a linear direction or radial center and radius. Unpainted Krasnow cells continue to use the ordinary Fauxlogram Gradient settings.
One region may contain several disconnected painted shapes. Combined Region applies one continuous progression across their shared bounds while leaving the gaps empty. Each Painted Shape restarts the progression for every separate brush stroke. Whole Artwork evaluates the guide against the complete artwork bounds even though only the painted cells receive it.
Gradient Start, End, Curve, and Reverse control carrier progression independently for each region. Grating Orientation may run parallel or perpendicular to the local gradient, use a fixed angle, or add an angular offset. Linear and radial gradient progression are therefore independent from the open-line orientation engraved inside each Krasnow cell.
Painted regions are evaluated in drawing order: a later painted region takes ownership of a cell from an earlier region, and an eraser stroke returns that cell to the ordinary shared Krasnow gradient. The painter never creates a second copy of source geometry. Every Krasnow cell still has one source swatch owner, one painted-region owner at most, and one carrier layer.
Mix ordinary vectors and gratings by swatch
To place diffraction only in selected color regions, choose Choose by swatch under Geometry Style. In the routing grid, select one or more configured swatches and use Selected to Krasnow, Selected to Vectors, or the individual row selectors. The shared Krasnow Grating settings section appears as soon as at least one swatch uses Krasnow.
This is useful when a subject, emblem, text, outline, or physically colored metal region should remain a normal filled vector while selected highlights or backgrounds shimmer. Every prepared source region receives exactly one geometry treatment. Black remains Normal Vectors in mixed routing so transformed layers cannot overlap a second Black treatment.
You can also assign another group of swatches to Glyphs in the same job. Shared Glyph settings and shared Krasnow settings apply to their respective routed swatches, while the remaining swatches stay continuous vectors.
Review the artwork, palette, enabled swatches, dimensions, Image Style, Geometry Style, routing assignments, and shared geometry settings. When the configuration is ready, select Upload and rasterize to upload the inputs and submit the job.
Follow the job until it reaches Completed. Signed-in members can monitor it in the on-page activity display or Job History, including after navigating away. Guests must keep the Rasterizer page open and follow the on-page status because guest jobs are not retained in Job History. If the job fails, read the final error before changing settings and submitting another run.
Inspect the SVG and LightBurn project
After the job reaches Completed, download whichever output files you need. SVG preserves the generated geometry but does not embed LightBurn laser settings. The .lbrn2 project contains the applicable layers and copied settings, and its Notes record the job type, image processing, geometry treatment, and public parameters.
In LightBurn, verify the physical dimensions, origin, layer order, output switches, cut mode, speed, min and max power, frequency, q-pulse duration when present, passes, line interval, scan angle, bidirectional behavior, crosshatch, and angles per pass. Inspect at high zoom for a full-canvas Black backing shape or other positive-area overlap. There should be no region intended for two different settings.
If one color reaches all four edges of the image, LightBurn may show that layer as one large outer vector that appears to cover the entire artwork. This is not necessarily an overlap. Before changing or deleting it, zoom in and check whether the outlines of the shapes on the other color layers also appear inside it as knockout holes. When those holes are present, the large vector engraves only the background around the other shapes, so the layers still do not overlap. Do not delete only the large outer vector: without its outer boundary, LightBurn may treat the inner knockout outlines as filled shapes and engrave those areas a second time. Change the layer only if the knockout holes are missing or inspection reveals a real positive-area overlap.
Dense files can make LightBurn appear frozen during Frame, Send, or Start. For projects over 50 MB, Rasterizer adds a warning to Notes and has already configured the generated project to avoid the expensive path optimizations. Allow LightBurn time to finish its calculations.
Troubleshoot by symptom
No shimmer or directional change usually points to the physical recipe, focus, groove spacing, surface, or lighting rather than artwork color. Return to a small calibration grid. Gold where green was expected is not corrected reliably by one universal speed change; compare neighboring calibrated carriers under the intended viewing geometry and adjust the mapping from measured evidence.
Large flat shapes instead of visible grating cells usually indicate the wrong Image Style or Geometry Style, an incompatible specialized filter, or merged geometry being inspected at too little zoom. Unwanted dark corners usually indicate that transparent background was not cropped or that Preserve Black was used on source pixels that were actually opaque Black.
A beautiful result under one lamp that disappears elsewhere is not necessarily a processing failure. Document the illumination direction and intended viewing distance as part of the finished piece. If the response cannot be separated or repeated after calibration, describe it as kinetic or iridescent texture rather than a predictable fauxlogram.
Record a reproducible final recipe
Keep the source image, palette or library revision, material batch, focus reference, lens, fixture orientation, cleaning method, light position, viewing position, Rasterizer job ID, and final .lbrn2 file together. Photograph the accepted engraving from the defined viewpoints. A color name alone is not enough to reproduce an angular structural-color result.
Promote a design from test to finished artwork only after a small coupon and a representative detail section both pass. The final acceptance check is physical: the intended regions change as expected, ordinary vector regions remain stable, no area receives multiple incompatible settings, and the effect survives the actual display lighting.
For the underlying grating mathematics and reference scripts, see Ben Krasnow's MOPA Laser Diffraction Gratings repository.
If you are not comfortable uploading laser settings, or do not use LightBurn, and still want to try the geometry produced by Rasterizer, use SVG-Only mode. It exports the generated geometry without embedding or applying LightBurn laser settings.