Smaller handle · optical evaluation

The compact upper and lower layouts are the new defaults in the split coverage viewer. Exactly two cameras and every light module, shared driver and modelled wiring reserve remain in the evaluated handle. Coverage requires an unobstructed camera route, an unobstructed structured-source route and sufficient ray separation.

These are conditional geometric results. The 940 nm source uses a continuous illumination cone as a proxy for fixed-dot access. The study does not simulate the manufacturer's dot pattern, prove correspondence, or establish fluorescence/NIR diagnostic performance. Measured lens distortion, spectral response and source pupil data are still required.

Coverage is not image detail. Median camera sampling is 0.071–0.073 mm per pixel, but a sampling proxy is not measured reconstruction error. Each percentage above is a single seated pose; the prescription is captured over several rigid re-seatings and stitched. These geometric results do not establish fine dental reconstruction or caries/plaque detection.

Physical compact configurations

Search and comparison

The original handle exterior and its two-camera, two-light packing are carried over unchanged from the earlier compact study. Only the tray mirror positions and orientations were searched again; the R24 6 × 6 mm prescription, the trays, the seat candidates, the devices and the mirror counts are those of the symmetric design these layouts replace.

The mirrors were searched against 7 patients’ arches at once (6 on the lower, where one arch is longer than the tray): the reference scan behind every earlier design and 6 further intraoral scans, each seated in the unchanged trays by a rule that reproduces the reference seats within 0.25 mm. A cap must clear every arch. Each candidate was traced at every shot of each arch's capture sequence, and a surface point counts at the best shot that reaches it.

Candidates were scored by a balanced objective: the sum over (arch, surface class) of log(C + 0.05), where C is the area-weighted value of that class on that arch and a triangulating pair is worth 0.3 + 0.7 × q_camera, with q = min(1, (target/pitch)^weight), target 0.15 mm per pixel and weight 2. The superseded search ranked min(q_camera, q_light), which the light head's raster reduced to the light leg alone. Mirrors are chosen as exact mirror-image pairs about x = 0, greedily and then by exchanging whole pairs while any exchange raised the objective. This is the best found bounded search, not proof of a global optical optimum.

Independent held-out tests on the reference arch use the same frozen sets as the earlier study: 8,000 upper samples (5,900 primary) with seed 20260920101 and 6,000 lower primary samples with seed 20260920102. Sampling is uniform by area.

The lower layout was searched and evaluated with an opaque tongue-and-plate proxy appended to the anatomy; the upper was not. Separate audits check complete body/wiring enclosure, intersections, remaining mirror seats, connected material, finite reflection paths, exported masks and intervals. Browser mesh decoding and STL generation are compared with the frozen physical files.

Single-pose held-out access on the reference arch is 52.88% upper and 62.10% lower over the bottom-and-side primary regions. The upper palate proxy reaches 43.87% in one pose. These are the figures the coverage viewer draws for one pose.

Mirrors are placed as exact mirror-image pairs about the midline, so every left mirror has a right twin at the reflected position and orientation, fed by the mirrored device. Across the 7-arch search cohort, with the capture sequences published before this change, the stitched share resolved at 0.150 mm per pixel rises from 75.6% to 89.0% on average for the upper (worst arch 60.6% to 76.0%) and from 73.7% to 76.0% for the lower, against the symmetric layouts searched on the reference arch alone.

The superseded 40-mirror defaults reached 99.58% and 99.87% in one pose. They did so with strongly convex mirrors whose median sampling was 2.094 and 2.365 mm per pixel — 29× and 33× coarser than these layouts, and too coarse for fine dental detail. The redesign trades single-pose reach for image sampling and recovers the reach with multiple shots.

Both defaults retain the supplied handle envelope, approximately 30.19 × 108.09 × 15.30 mm (width × length × height), with no added envelope volume.

No added passive seat reinforcement was required: the independent seat audit found tray material behind and beside every cap.

Optical assumptions and limits

• Exactly two cameras, two combined light heads, one shared driver strip and opaque wiring segments per layout. The tray contains mirrors and passive supports only.
• Camera assembly reserves are 5 × 5 × 8 mm. Light-head reserves are 8 × 8 × 12 mm. The shared driver strip reserve is 12 × 40 × 4 mm. These are proposed assemblies, not qualified purchased systems.
• Each camera uses a 4208 × 3120 ideal rectilinear surrogate with a 70° horizontal and 54.87° vertical field (fx 3004.8 px). Actual intrinsics and lens distortion have not been calibrated.
• The structured source uses a point pupil and continuous rectangular cone of 109° horizontally and 95° vertically, based on the Himax TL25-W 940 nm fixed-dot projector. Virtual source coordinates encode the cone; they are not a physical pixel array.
• Both source and camera routes are direct or use one finite reflection. The acute camera–source ray angle must be at least 10°. Full scan triangles, remaining housing, component and wire boxes, other mirrors and their backing surfaces obstruct routes.
• White, 450 nm visible-blue fluorescence for caries and plaque/biofilm, and 850 nm class NIR flood are retained as separate module requirements. No UV channel is proposed. Their individual pupils, signals and diagnostic performance are not inferred from structured-source coverage.
• MULTI-SHOT PRESCRIPTION. Every single-pose figure is ONE seated pose. The tray is captured over several rigid re-seatings and stitched; the stitched figures are in the coverage viewer and on the Specifications page, and cohort-study/README.md gives them for every arch of the search cohort. They are simulation under assumed priors, not measurement.
• Geometric access is conditional on the stated lens and source assumptions. The actual fixed-dot pattern, short-range reflected contrast, correspondence, finite entrance pupils, focus, blur, radiometry and 940 nm camera/filter compatibility are not validated.
• The gentle R24 caps trade single-pose reach for sampling. Single-pose access on the reference arch is 52.9% upper and 62.1% lower, with median camera sampling 0.073 and 0.071 mm per pixel, against 2.094 and 2.365 mm per pixel for the superseded 40-mirror defaults. Reported mm/pixel describes the best eligible camera path in the worst local tangent direction; it is not measured reconstruction error.
• R24 depth of field is about ±2.2 mm against camera-to-mirror legs spanning 32–101 mm, so the design needs designed focal zones or focus bracketing across the shots. No workable (pose, focus) assignment has been demonstrated. This is the largest open item.
• Merging shots assumes the motion between re-seatings is known to the precision of the rest of the budget. No registration or stitching error is modelled anywhere in these figures.
• The optical layouts start with a 1.0 mm pre-port wall allocation and 0.35 mm body-cavity clearance. Ports can leave locally thin rims and walls. Downloaded physical audits report sampled post-port normal thickness, separated by declared optical-cut exits; they do not certify a global minimum wall or a manufacturable enclosure.
• Cable reserves use overlapping opaque segments with declared terminal contacts. They account for ray blocking but do not prove individual cable packing, bend radius, strain relief, connector access, routed electronics or heat removal. A battery and extra processing need a further space budget.
• This study is stationary within a pose. Results apply to the 7 supplied arches and their large-tray seats (6 on the lower: one lower arch is longer than the unchanged tray and does not fit it). Population fit, unscanned anatomy and clinical diagnostic performance remain unestablished.

Optical study record

compact physical validation · compact result validation · compact cone validation · compact delivery validation