Optics — manual

TIR lens

A total internal reflection lens: a refracting dome at the centre, surrounded by one or more rings that collect the grazing light and redirect it by total internal reflection at the outer flank. It is used over an LED where a narrow beam is required without discarding a large fraction of the flux.

A practical order is Collection, which sets the flux collected and the number of rings; then Optic, the material and the distances; then Output beam, which sets the output distribution.

Collection

The source fan is divided in two: below the switch angle the central dome acts, above it the TIR rings.

Centre→TIR switch [°]

Divides the source fan. Below this angle light enters the central dome and is deviated by refraction alone; above it, light enters the flank of a ring, is turned by total internal reflection at the outer wall, and leaves through the front.

It is the principal flux split of the part. Increasing it assigns more flux to the central dome, which must then deviate rays arriving at larger incidence, and leaves a narrower fan to be divided among the rings.starts at 30, 1 to 88

Max angle [°]

Light beyond this angle does not reach the part. Increasing it collects a larger fraction of the emitted flux at a rising cost in material: the outermost ring grows quickly, while the added angular interval carries little flux from a Lambertian source, whose intensity falls as cos θ.starts at 89, 2 to 89

Sections PRO

A single section turns the whole outer fan at one wall, which requires depth. Dividing the fan among several rings reduces the depth of each, at the cost of a step between consecutive sections; the step carries no useful light.

How the fan is distributed among the sections is set by the next field.starts at 3, 1 to 12

Section split

Equal angular intervals produce sections of unequal depth: outer sections sit at larger radius and require less depth for the same angular span, so depth decreases outwards.

The other two settings distribute the angles unequally. One equalises the depths, to within a fraction of a percent; the other reverses the gradient so that the outermost ring is the deepest, which suits designs in which the rim is gripped or sealed.

Optic

Refractive index

PMMA 1.49, polycarbonate 1.59, optical silicone about 1.41. The value sets the deviation at every refracting surface and the critical angle governing the total internal reflection. A higher index reduces the surface slopes required and widens the margin at the TIR wall.

A single index is used, so the design is monochromatic; dispersion is not modelled.starts at 1.49, 1.01 to 3

Vertex on axis [mm]

Sets the scale of the part, as the remaining geometry is constructed outward from it.

Reducing it gives a smaller and more efficient optic, and increases the angular size of the emitter seen from the surfaces, so the spread from a finite source grows in proportion.starts at 3, 0.2 to 40

Lens thickness [mm]

A minimum wall between the highest point reached by the internal geometry and the front of the part. The constraint is from moulding rather than optics.

It acts as a lower bound. With shaped exit faces the hooking may require more material than specified, in which case the value is raised rather than allowing a face to cut into the geometry behind it. This is why the central zone can be recessed with the other values at zero: the recess is the residual once the outer faces have taken the height they require.starts at 3, 0.2 to 30

Fillet radius [mm]

Adjacent designed surfaces generally meet at a cusp, which no mould or tool reproduces. This applies a radius to them.

A fillet is not a designed surface: rays incident on it are deviated by the radius, so they are drawn in the warning colour and counted as stray light. The stray fraction grows with the radius. In the STEP export the fillets are emitted as faces separate from the optical zones.starts at 0, 0 to 5

Optical draft [°]

The inner flank of a ring, through which light enters on its way to the reflecting wall. The draft required for mould release is specified here in degrees from the axis.

Because the face refracts, the draft sets the incidence angle at the TIR wall, which determines whether total internal reflection occurs. It cannot be selected from the moulding constraint alone.starts at 4, 0.5 to 45

Shadow step

Consecutive sections are separated by a step that carries no designed light; it exists for moulding and release.

The step can be specified two ways, and this selects which: a flat ring of given width in millimetres, or a wall of given draft in degrees. With shaped exit faces the hooking determines the slope, and the value below becomes an output.Ring [mm] · Draft [°]

Shadow value

Always positive; the direction follows from the geometry. The unit shown beside the field follows the mode selected above.starts at 1, 0.1 to 45

Exit draft [°]

With shaped exit faces, each face is positioned so that its first ray leaves parallel to the axis and meets the end of the preceding face. The match is generally not exact, and a gap remains between the end of one face and the start of the next.

This sets the draft of the wall closing that gap. The field appears only where a gap exists.starts at 2, 0.5 to 45

Target diameter [mm] PRO

The diameter is normally an output of the geometry. Where it is specified instead, enter it here and use Fit vertex, which solves for the vertex position producing that diameter with the other parameters unchanged.

The solver can fail: a diameter unreachable by any vertex position at the current collection angles has no solution, and this is reported rather than returning the nearest value.starts at 30, 1 to 300

Output beam

The cone limits set where the light goes; the exponent sets its distribution within that cone. On a narrow cone the exponent has little effect: cos⁵ of 12° is 0.90.

Shaped exit faces PRO

Selects which surface controls the output distribution.

Off — the front of the part is flat. The reflecting wall collimates, the flat face refracts what reaches it, and the output is the internal divergence transformed by that refraction.

On — each zone has a shaped exit face. These faces conserve flux and map it onto the target. The target beam parameters below apply only in this mode.on or off

Internal divergence [°]

The semi-angle of the bundle propagating inside the material, before the exit face.

A negative value makes the first ray of each section leave parallel to the axis. That is the condition under which each exit face begins where the preceding one ended, so consecutive sections hook together rather than being positioned independently. Without it the faces accumulate height and the part grows.starts at 0, -40 to 40

Central beam inside [°]

The inner edge of the interval filled by the central dome. With the field below it fixes the angular span of the central zone's contribution.

Same sign as the outer value: the zone illuminates an annulus, and the centre of the beam is left to the other zones.

Opposite signs: the zone covers the beam through the axis. The rays cross the axis to do so, so the centre of the spot is illuminated by light from the opposite side.starts at 0, -89 to 89

Central beam outside [°]

The outer edge of the interval filled by the central dome. That interval receives all the flux the dome collects, distributed according to the target exponent.starts at 0, -89 to 89

Sections inside [°]

The rings are aimed independently of the central dome, so the dome can fill the centre of the beam while the rings form its edge, or both can cover the same interval and add.

Zero in both section fields specifies zero to zero, a collimated output in which every ring sends its light parallel to the axis. It does not mean that the section values follow the central ones.starts at 0, -89 to 89

Sections outside [°]

The far edge of the interval filled by the rings. Each section covers the whole interval, so the sections overlap rather than tile it, which reduces the effect of an individual section being slightly off.starts at 0, -89 to 89

Cos exponent

The exit face conserves flux and requires a target distribution as well as a target interval. The specified illuminance falls as cos^n θ across the spot.

n = 0 gives constant illuminance, edge equal to centre. Increasing n concentrates flux towards the axis.

The effect is small on narrow beams. The exponent acts on cos θ, which varies little over a small cone: at 12°, cos⁵θ = 0.90, so n = 0 and n = 5 differ by about 10% across the spot. Over a 40° cone the same exponent brings the edge to 0.26 of the centre. Where varying n produces no visible change, the cone is too narrow for it to act on.starts at 0, 0 to 8

V exit face [°] PRO

An alternative front surface: one straight cone closes the TIR zone in a single sweep, from the edge of the central dome to the rim, in place of one shaped face per section. It is a common arrangement on moulded TIR optics, chosen for manufacture and appearance as much as for optics.

A straight cone diverges the transmitted bundle, so the reflecting wall behind it is designed to converge by the same amount. Zero disables the cone and returns the front to the per-section faces.starts at 0, 0 to 60

Curved entry face

With a straight entry flank the incidence angle at the reflecting wall follows from the draft. Curving the flank imposes the incidence angle instead and holds it along the face.

Measured against a straight face of the same draft, the TIR margin is wider. Measured against a straight face drafted at −20° or steeper, the margin is equal and the part is larger. The option requires the V face, and requires several sections: a single section spans too wide a fan for one internal angle to suit.on or off

Max face recline [°]

Sets the inclination of the curved flank. Greater inclination brings light to the reflecting wall at larger incidence, increasing the margin over the critical angle and reducing the fraction of rays transmitted rather than reflected.

The cost is radial: a reclined face occupies more room and displaces every section outward, so the diameter grows as the margin improves.starts at 70, 40 to 80

Working plane

The beam is a far-field beam: this distance scales the spot, not its distribution.

Distance [mm]

Sets where the illuminance figures are computed. The design works in angles, so this distance scales the spot linearly and the illuminance as its inverse square; the distribution is unchanged.

Set it to the distance being specified, so the reported figures correspond.starts at 1000, 50 to 50000

Wall washer

An extruded reflector producing uniform illuminance on a wall from top to bottom. Unlike the other two it is not a solid of revolution: the profile is a cross-section repeated along the length of the luminaire.

Output beam is the principal group. It specifies the limits of the illuminated band, either as angles or as heights on the wall; the two are related through the wall distance and are kept consistent.

Source

Axis tilt [°]

Sets the direction of the source axis. The collection angles below are measured from this axis rather than from the vertical, so inclining the source rotates the collected fan without changing its width.

It represents a board mounted at an angle within the luminaire without altering the collection values.starts at 0, -90 to 90

Source exponent

The source side of the flux budget: the fall-off of the LED intensity away from its axis, as cos^n θ. n = 1 is Lambertian.

A loaded intensity file replaces this value; the two are not combined.starts at 1, 0.1 to 6

Luminaire length [mm]

The reflector is an extrusion, fed in practice by a line of emitters rather than a point. This sets the length of that line.

Zero treats the source as a point, which is the design assumption. A finite length affects the result at the ends of the luminaire and at short wall distances, where the line no longer approximates an infinite one — the same conditions under which the fall-off exponent below takes a different value.starts at 1000, 0 to 20000

Collection

Upper angle [°]

Light above this angle does not reach the reflector. It leaves the luminaire directly, and its distribution is not part of this design.starts at 60, -89 to 90

Lower angle [°]

The interval between the two limits is the flux available to the reflector, redistributed over the illuminated band specified below. A narrow collection interval spread over a tall band gives proportionally lower illuminance.starts at -60, -90 to 89

First point distance [mm]

The marching construction requires a starting point, and this sets it.

It determines the overall size of the section, since the remaining geometry is constructed from it, and is the parameter to use when fitting the reflector into a given envelope.starts at 40, 1 to 300

Optic

Correction strength β

A real reflector scatters, which convolves the distribution the geometry was designed to produce. Given a measured BSDF, this pre-distorts the target so that the scatter restores it. Zero designs for a specular surface; one applies the correction at full strength.

The correction is first order and is valid where the scatter lobe is narrow relative to the structure being corrected. On strongly diffusing materials that condition does not hold. Measured on 2000GP, which scatters about 70% of the flux outside the useful field, the departure from uniformity increases monotonically with β, from 44% at zero to 55% at one.

The ray-trace evaluates the result directly. On specular and lightly textured surfaces the correction behaves as specified.

Profile points

Sets the number of marching steps along the section, and with it the resolution of the exported profile. Each point is a construction step, so the value also affects recomputation time.starts at 501, 21 to 4001

Output beam

Angles and heights are related through the wall distance and are kept consistent; either may be entered.

Upper output [°]

With the lower edge below, it defines the interval over which the collected fan is redistributed.starts at -5.71, -89 to 89

Lower output [°]

The interval between the two edges determines the illuminance: a taller band distributes the same flux over more wall, and its lower end is illuminated at larger incidence, where the fall-off compensation below applies most strongly.starts at -72.12, -89 to 89

Top edge height [mm]

The upper edge expressed as a height on the wall rather than as an angle.

Heights and angles are related through the wall distance and are kept consistent; entering either updates the other.starts at -100, -20000 to 20000

Target height [mm]

The vertical extent of the band, measured downward from its upper edge, and coupled to the angles through the wall distance.starts at 3000, 1 to 20000

Wall cos exponent

A uniform beam does not produce uniform illuminance on a wall: the lower end of the band is further away and illuminated at larger incidence. This sets how much of that fall-off the design compensates.

The exponent depends on the source geometry rather than on the reflector: 3 for a point, 2 for a line long compared with the wall distance. A finite luminaire lies between the two, nearer 2 at mid-length and nearer 3 at the ends.starts at 2.5, 0 to 6

Working plane

Wall distance [mm]

Converts the angles to heights, and determines the validity of the far-field assumption.

Below roughly 25 times the size of the reflector section, the prediction and the ray-trace diverge. The prediction treats the reflector as a point, which does not hold at that distance; the ray-trace does. Wall washers are frequently mounted within that range.starts at 1000, 20 to 50000

Parabolic

A reflector of revolution with a central aperture for the LED. It has fewer parameters than the other two, and is a suitable starting point for the relationship between collection and target.

Source

LED hole diameter [mm]

The aperture determines where the reflecting surface can begin. Flux leaving through it is undesigned and falls in the centre of the beam.

A larger aperture simplifies assembly and increases the stray flux on axis.starts at 8, 0.5 to 60

Emitter size [mm]

Zero corresponds to the point source assumed by the construction. A finite width convolves the beam by an amount that grows as the reflector is made smaller; only the ray-trace accounts for it.starts at 0, 0 to 20

Distribution exponent

With an emitter of finite width, each marching step begins at some point on it. This sets how that point moves along the emitter as the surface is constructed.starts at 1, 0.1 to 6

Collection

The central aperture is not material: it is the opening for the LED, and it sets where the reflector begins.

Min angle [°]

Follows from the aperture and the geometry rather than being specified directly. It is the reason a reflector alone does not produce a controlled beam: the centre of the distribution always carries undesigned flux.starts at 25, 0 to 89

Max angle [°]

Increasing it towards 90° adds rim diameter for little additional flux, since the intensity of a Lambertian source falls as cos θ.starts at 89, 1 to 90

Output beam

Half-angle [°]

Specifies the half-angle of the output.

A target wider than the innermost collected angle has no solution with a continuous mirror, since the surface would have to direct light back through the fan it collects. Where the beam does not widen, this is generally the constraint, and the remedy is a larger reflector or a smaller aperture.starts at 15, 0 to 89

Cos exponent

Sets the distribution within the beam, as cos^n θ.

The surface is constructed by conserving flux. For a reflector of revolution the integral is over annuli: the flux between two angles is I(θ)·2π·sin θ·dθ, and a target illuminance is converted to an intensity, E = I·cos³θ/D², before being compared with the source. Both factors are included. Omitting them assigns finite flux per degree to the axis, where the annulus has zero area, and the illuminance diverges as 1/ρ.starts at 0, 0 to 8

Working plane

Distance [mm]

The design works in angles, so this distance scales the spot linearly and the illuminance as its inverse square. Set it to the distance being specified.starts at 1000, 50 to 50000

Sketch

A drawing surface for geometries the other tabs do not cover. Curves are dragged from the palette, snapped to each other by their endpoints, and tested with a fan of rays.

Endpoints left close together join, and from then on move together; double-clicking the point separates them. The padlock in the inspector is a separate function: it fixes a point at its coordinates and is not a link between curves. A closed perimeter defines an interior, in which rays refract.

The parabola lies with its axis along the rotation of its pose, so rotation 0 puts the axis horizontal. It is cut between two heights above that axis, measured from the vertex, which lets a segment that does not pass through the vertex be drawn — the reflector of a CPC is one. Equal and opposite values give a segment symmetric about the axis. Changing them re-cuts the curve without turning it, and the focus marker follows.

Rotating a parabola turns it about its focus, so the focus stays where it was put while the axis is tilted — the two steps of setting up a CPC. A pinned end overrides this and holds its own position instead.

Each end also carries its tangent, which can be typed, and a button that turns the curve about that end until the tangent is perpendicular to the axis. That is the condition for the mirrored half to meet the curve without a corner, and it is flagged when an end sits on the axis without satisfying it.

Curves

Mirrored half

Mirrors the drawing across the axis. The board holds the meridian half of a solid of revolution, and the lower half follows from it rather than being drawn separately.

Rays are traced against the mirrored half as well.on or off

Common controls

The lower part of the panel does not change with the tab: the same rays, the same verification, the same export. It is hidden on Sketch, which has nothing to compute.

Rays

Count

The rays are placed by the same construction that generates the surfaces, so they cannot disagree with it; increasing the count fills in the fan.

The ray-trace below is an independent model, and can.

Stroke opacity

With a full fan the strokes overlap and obscure the geometry. Reducing the opacity keeps the density of the bundle visible while showing the surfaces beneath.

Show rays

A single control for the whole bundle. Separate controls for the paths inside and outside the optic would require classifying each segment as one or the other, and with shaped exit faces that classification was unreliable.on or off

Mirrored half

The lower half is drawn by reflection and contains no additional computed data.

The export contains the meridian half only, since the receiving system revolves it; a doubled profile would self-intersect.on or off

Verification

The remaining outputs are derived from the construction. This traces rays against the finished profile and measures the result, which is an independent check.

Ray-trace the profile

An independent model: rays are launched from the emitter and traced against the finished profile, and the result is measured rather than derived from the construction.

It is the only measure that accounts for a source of finite size, since the prediction works in angles. It is off by default because it adds a few tenths of a second to each recomputation.on or off

Export profile

Exporting requires a premium key, on every tab. The design itself, and every measurement of it, stay open. The export contains the curve as computed — for a solid of revolution, the meridian half only. The receiving system revolves it; a doubled profile would self-intersect.

File name PRO

One name is used for every format, so that the CSV, the SolidWorks curve and the STEP of the same design share it.

For the STEP it is also written into the file as the name of the part.

Format PRO

CSV and SolidWorks both export the meridian curve as points, the first as a table and the second in the form SolidWorks imports as a sketch curve. The receiving system revolves or extrudes them.

TracePro profile is the same curve in the format that optimizer reads.

STEP 3D exports the geometry rather than the curve. Where the profile meets the axis at both ends the result is a closed solid; otherwise it is an open surface. A lens is therefore exported as a solid and the reflectors as surfaces. Each optical zone is a separate named face, and the fillets are separate from the optical zones, so that properties can be assigned per zone.

Presets

Name

Presets are stored in this browser. Export all… writes them to a file, which is also how they are transferred to another machine or preserved when site data is cleared.