Parameters are not independent knobs
A setting only becomes meaningful inside a relationship: power at a given speed, NA at a given path spacing, oxygen at a given diffusion rate, development time at a given conversion field.
Use the atlas to trace which physical or numerical route a control changes. “Turn it up” describes a directional intuition within this model, not a universal recipe for a real fabrication system.
Path and slicing
These controls decide where the focus travels, how neighboring lines overlap, and when a region is revisited.
Layer height
µmThe vertical distance between successive written slices.
- Turn it up
- Uses fewer, more widely separated layers. Exposure is faster, but vertical detail and overlap decrease.
- Watch it with
- Numerical aperture, wavelength, hatch spacing, and the smallest vertical feature.
- Inside this model
- Rebuilds the deterministic three-dimensional path and therefore changes layer count, path length, timing, and exposure overlap.
Hatch spacing
µmThe lateral distance between neighboring interior scan lines.
- Turn it up
- Shortens the path and reduces overlap. Excessive spacing can leave weakly exposed gaps between lines.
- Watch it with
- Focal width, power, speed, layer height, and contour coverage.
- Inside this model
- Changes the actual path samples through the occupancy rather than applying a cosmetic density multiplier.
Hatch angle
°The in-plane direction followed by the interior fill lines.
- Turn it up
- Rotates the hatch; it has no universal stronger-or-weaker direction. Its effect depends on geometry and neighboring layers.
- Watch it with
- Feature orientation, boundary coverage, layer-to-layer rotation, and unsupported spans.
- Inside this model
- Rotates the generated scan trajectory inside each layer while preserving the occupied target volume.
Contour passes
countHow many boundary-following traces reinforce the outside of each slice.
- Turn it up
- Adds exposure near boundaries and lengthens the path. Edges may become more robust but also broader or overexposed.
- Watch it with
- Hatch spacing, power, speed, off-target activation, and fine cavities.
- Inside this model
- Adds real contour trajectories to the exposure schedule; it is not a post-processing outline.
Exposure passes
countHow many times the complete path is revisited.
- Turn it up
- Accumulates more exposure, but later passes encounter chemistry altered by earlier passes.
- Watch it with
- Initiator depletion, oxygen recovery, radical loss, power, and total physical time.
- Inside this model
- Repeats the timed path against the evolving authoritative volume instead of multiplying a finished conversion field.
Light and motion
These are physical-style process inputs that shape the focal field, pulse energy, nonlinear source, and dwell history.
Specimen power
mWThe average optical power delivered at the specimen plane.
- Turn it up
- Strengthens the two-photon source rapidly. In this model the source scales with P² when other light inputs stay fixed.
- Watch it with
- Scan speed, repetition rate, pulse duration, numerical aperture, and off-target activation.
- Inside this model
- Power normalizes the vectorial pupil and enters the nonlinear source; it is not divided uniformly among voxels.
Scan speed
µm/sHow quickly the focus moves along the same geometric path.
- Turn it up
- Reduces dwell time and usually lowers accumulated conversion while shortening the physical exposure history.
- Watch it with
- Power, hatch spacing, passes, diffusion, oxygen recovery, and radical lifetime.
- Inside this model
- Changes illuminated and dark time between path samples. It does not directly rescale the optical field.
Numerical aperture
dimensionlessHow broadly the objective accepts light and how tightly it can concentrate the same total specimen power.
- Turn it up
- Narrows the focal distribution and raises central concentration, but can reduce overlap and does not guarantee greater whole-object survival.
- Watch it with
- Wavelength, voxel pitch, hatch and layer spacing, polarization, and aberration.
- Inside this model
- Sets the objective semi-angle in a normalized vectorial Debye field from NA 0.01 to 1.49. The narrow core is volume-averaged when the grid under-resolves it; broad low-NA support is bounded by the simulated volume.
Wavelength
nmThe optical wavelength used to form the focus.
- Turn it up
- Broadens diffraction-controlled spatial scales for the same NA. A real material’s absorption response may also change.
- Watch it with
- NA, PI absorption peak, objective transmission, aberration, and voxel resolution.
- Inside this model
- Changes focal-field geometry and is evaluated against the exploratory PI absorption spectrum.
PI absorption peak
nmThe excitation wavelength at which the modeled photoinitiator response is strongest.
- Turn it up
- Moves the center of the absorption envelope toward longer wavelengths without changing the optical wavelength itself.
- Watch it with
- Laser wavelength, focal resolution, source strength, power, and the spectrum of a real photoinitiator.
- Inside this model
- Centers a normalized Gaussian two-photon response with a fixed 160 nm FWHM. It is an exploratory spectral shape, not a fitted material spectrum.
Pulse duration
fsHow long each ultrafast pulse lasts.
- Turn it up
- Spreads the same pulse energy over more time, lowering the peak-power proxy and the model’s nonlinear source.
- Watch it with
- Average power, repetition rate, dispersion, photochemistry, and thermal accumulation.
- Inside this model
- At fixed average power and repetition rate, the source scales approximately with 1/τₚ. Pulse shape and dispersion are not resolved.
Repetition rate
MHzHow many pulses arrive each second.
- Turn it up
- At fixed average power, creates more frequent but less energetic pulses; the current source therefore decreases with 1/f.
- Watch it with
- Power, pulse duration, radical lifetime, oxygen recovery, and heat accumulation.
- Inside this model
- Sets pulse energy P/f and peak-power proxy. Individual pulses are summarized rather than temporally resolved one by one.
Resin chemistry and transport
These coefficients control how excitation becomes radicals, how inhibition competes, and how species move through the volume.
Initial photoinitiator
relativeThe starting reservoir of molecules available to create reactive species.
- Turn it up
- Provides more initiation capacity and delays exhaustion, subject to oxygen inhibition and depletion.
- Watch it with
- PI depletion, radical yield, oxygen, source strength, and repeated passes.
- Inside this model
- Initializes the photoinitiator field with a dimensionless relative concentration; it is not a fitted molar concentration.
Boundary oxygen
relativeThe oxygen level available at the volume boundary—a replenishable chemical brake on radicals.
- Turn it up
- Strengthens inhibition and can delay or suppress conversion, especially in weakly exposed or boundary-adjacent regions.
- Watch it with
- Oxygen quenching, oxygen diffusion, radical yield, power, and scan timing.
- Inside this model
- Sets the boundary reservoir and initial oxygen field in relative units rather than a calibrated concentration.
Photoinitiator depletion
T₀⁻¹How quickly exposure consumes the available photoinitiator.
- Turn it up
- Produces faster depletion, making later exposure less productive even when the optical source is unchanged.
- Watch it with
- Initial initiator, source strength, pass count, PI diffusion, and radical yield.
- Inside this model
- Appears in the initiator loss term −βsp using the model’s normalized time scale.
Radical yield
relativeHow efficiently an absorbed excitation creates active radicals in the compact chemistry model.
- Turn it up
- Generates more radicals from the same source before quenching, loss, and termination act.
- Watch it with
- Initiator, oxygen quenching, termination, propagation, and source strength.
- Inside this model
- Multiplies the radical generation term ηsp; it is not a measured quantum yield.
Dark radical loss
T₀⁻¹How quickly radicals disappear even when oxygen and radical–radical termination are separated out.
- Turn it up
- Shortens radical memory between path samples and reduces conversion accumulated during dark intervals.
- Watch it with
- Scan speed, path jumps, repetition rate, passes, and propagation.
- Inside this model
- Applies a linear radical decay term −δr on the normalized chemical clock.
Oxygen quenching
relativeHow strongly local oxygen suppresses radical activity.
- Turn it up
- Makes a given oxygen field more inhibitory and sharpens the competition between exposure and oxygen supply.
- Watch it with
- Boundary oxygen, oxygen diffusion, radical yield, source strength, and scan dwell.
- Inside this model
- Controls the coupled oxygen–radical sink qor in the compact reaction system.
Bimolecular termination
relativeThe rate at which two active radicals meet and terminate one another.
- Turn it up
- Suppresses high radical concentrations disproportionately and limits runaway peaks.
- Watch it with
- Radical yield, diffusion, power, dwell time, and propagation.
- Inside this model
- Applies the nonlinear loss term −κr² with an exploratory dimensionless coefficient.
Propagation
T₀⁻¹How efficiently surviving radicals convert unreacted material into the network-forming state.
- Turn it up
- Builds conversion faster for the same radical history and approaches saturation sooner.
- Watch it with
- Radical yield, radical loss, oxygen, gel point, and development resistance.
- Inside this model
- Controls ∂ₜx = γr(1−x); it compresses a larger polymer reaction network into one conversion rate.
Oxygen diffusion
L₀²/T₀How quickly oxygen spreads and replenishes depleted regions.
- Turn it up
- Smooths oxygen gradients and can restore inhibition more quickly behind a moving focus.
- Watch it with
- Boundary oxygen, quenching, scan timing, feature size, and volume boundaries.
- Inside this model
- Scales the spatial Laplacian of the oxygen field on normalized length and time units.
Radical diffusion
L₀²/T₀How quickly radical activity spreads away from where it was generated.
- Turn it up
- Broadens and smooths radical fields, potentially lowering local peaks while activating nearby regions.
- Watch it with
- Radical lifetime, termination, hatch spacing, boundaries, and off-target conversion.
- Inside this model
- Diffuses the compact radical field; it does not resolve different radical species or chain lengths.
Photoinitiator diffusion
L₀²/T₀How quickly photoinitiator concentration redistributes after local depletion.
- Turn it up
- Refills depleted regions more quickly while spreading concentration gradients into neighbors.
- Watch it with
- PI depletion, pass timing, initial initiator, feature size, and volume boundaries.
- Inside this model
- Diffuses one normalized photoinitiator field without material-specific mobility or binding states.
Gelation and development
These controls decide when conversion counts as a connected network and how aggressively bath-accessible material is removed.
Gel point
conversionThe conversion level used to mark material as a connected, gelled network.
- Turn it up
- Requires more conversion before material counts as gelled, making survival criteria more demanding.
- Watch it with
- Propagation, exposure history, development resistance, and weak connections.
- Inside this model
- Classifies the continuous conversion field for gel statistics; development also depends continuously on conversion.
Base dissolution
T₀⁻¹The baseline rate at which accessible, weak material loses mass in developer.
- Turn it up
- Clears underconverted material faster and makes marginal regions less likely to remain.
- Watch it with
- Development time, gel resistance, bath depth, conversion, and narrow supports.
- Inside this model
- Sets the base rate in the compact remaining-mass equation; it is not fitted to a specific solvent protocol.
Gel resistance
dimensionlessHow strongly increasing conversion protects material against dissolution.
- Turn it up
- Makes highly converted regions much more resistant relative to weak regions, sharpening selective development.
- Watch it with
- Conversion distribution, gel point, base dissolution, and development time.
- Inside this model
- Places conversion in an exponential resistance factor rather than a binary keep-or-delete rule.
Development time
T₀How long the calculated structure remains exposed to the development process.
- Turn it up
- Removes more weak material and opens deeper access, but can erode marginally converted features.
- Watch it with
- Base dissolution, gel resistance, conversion gradients, access paths, and mechanical effects outside the model.
- Inside this model
- Advances bath-accessible dissolution for a normalized duration; rinsing, drying, stress, and capillary collapse remain outside scope.
The six comparisons worth learning first
Source strength and dwell time can both raise exposure, but they change the chemical clock differently.
A tighter focus can raise central intensity while reducing overlap between neighboring path samples.
Average power alone does not specify pulse energy or the nonlinear peak-power proxy.
Inhibition depends on both how fast oxygen is consumed and how fast it is replenished.
Generation competes with linear decay, oxygen quenching, and concentration-dependent termination.
The exposed field becomes a surviving structure only after transport and dissolution act.
Physical-looking units do not imply complete calibration
Power, speed, wavelength, numerical aperture, pulse duration, repetition rate, and geometric settings are expressed like experimental inputs. The compact chemistry coefficients use stable relative or normalized units because they are not fitted to a named material and protocol.