BBSRC–STFC FAF · APP88756

BBSRC · In-chamber fluorescence for Crossbeam + Katana

Compact fluorescence light path for correlative work inside a Zeiss Crossbeam chamber on the Katana volume-EM stack. Rev G clears the modeled apertures; remaining work is real optics and SEM integration, not more bore enlargement.

Purpose

The instrument needs a small fluorescence channel that fits the chamber envelope, shares the Mitutoyo 20× long-WD objective already used for optical navigation, and does not collide with the microtome, detectors or stage travel. The design feeds a horizontal camera arm through a dichroic cube and a 45° prism above the objective, with reciprocal LED excitation on the same shared bore.

This page summarises the mechanical Rev G state, the Blender geometric light-path check, and the caveats that still block a final print release.

Layout

Mechanicals — Rev G

Rev F vignetted off-axis image and illumination bundles at the shared/image bore, illumination approach and dichroic clear aperture. Rev G enlarges those openings and shifts the tube-lens / camera and LED seats so the sampled pupil rays clear. Onshape reports no solid–solid interferences among the 34 assembled parts after the correction; the nine-part print layout regenerates cleanly.

Confirmed mounting datums (mm)

Z0 (mount)

0.00

Sample

53.58

Obj. front

73.58

Optical axis

188.58

Item	Rev F	Rev G
Shared / image bore	Ø23 mm	Ø40 mm
Illumination approach bore	Ø24 mm	Ø40 mm
Dichroic clear rectangle	32 × 22 mm	46 × 32 mm
Dichroic glass envelope	35.6 × 25.2 × 1.1	50.8 × 35.6 × 1.1
Tube-lens / filter envelopes	Ø25–30 mm	Provisional Ø50.8 mm
Field stop	Ø1.8 mm	Ø3.6 mm @ f40 conjugate

Rev G Blender 3D overview — Rev G — Blender overview of housing envelopes and optical axis.

Rev G ray bundles — Rev G — image (orange) and reciprocal excitation (blue) clear the enlarged bores.

Rev F ray bundles showing vignette — Rev F (historical) — same sample shows corner vignette; red curves mark blocked diagnostic paths.

3D model & light-path

Interactive Rev G optical audit mesh (assets/rev_g_optical.glb). Rays were traced in Blender through specular prism reflection, planar-window and dichroic refraction (Snell), finite aperture tests and ideal thin lenses. Excitation is reciprocal from the objective pupil toward the field stop. An independent mesh ray-cast against dimension-matched aperture sections confirmed zero collisions for Rev G on the sampled set. Orange = image, blue = excitation, red = failed (none in this slim export).

Image Excitation Failed Drag to orbit · scroll to zoom · Blender Z-up → Three.js (x, z, −y)

Model from assets/rev_g_optical.glb; optional rays in mm. Geometric clearance only.

Caveats

This is a geometric clearance result, not a validation of image quality, LED radiance, field uniformity, photon budget, spectral filters, ghosts, MTF, print tolerance, thermal drift or vacuum compatibility. Ø50.8 lens and filter solids are provisional envelopes — not purchased parts. Pupil planes used in the sensitivity sweep are assumptions; Mitutoyo’s proprietary prescription is unavailable. Do not treat ideal thin-lens focus as evidence of real-lens performance. Real tube-lens BFD, relay prescription and SEM/vacuum fit remain open before final print release.