EmberScope

Optical baseline · 11 May 2026

EmberScope compact reflective baseline

The current optical direction is a compact folded reflective camera that protects the payload envelope while leaving room for detector, window, baffling, and mounting decisions.

Read the baseline Read optical literature Read detector path Read mission requirements Read detection pipeline Read calibration strategy Read survey model Read validation plan Read field-test plan

Dated statement — the architecture direction holds, the parameter set has moved on.

This page records the 11 May 2026 baseline decision: compact reflective optics with diamond-turnable mirrors. That direction still stands. The specific parameter values below have been superseded by the optimized four-mirror prescription of 10 June 2026 on the optics hub. Everything here is a design study; no optics have been fabricated.

Baseline statement

EmberScope starts from a compact folded reflective imager with three powered mirrors and freeform terms used only when they earn their keep.

3 mirrors Current starting family for the compact folded optical train.
40 mm Current entrance-aperture reference for the compact layout.
F/5.0 Current optical speed, still slower than the fast LWIR precedents.
150 mm Payload envelope target that keeps the baseline tied to drone mission practicality.

Why this baseline

The starting point is anchored in compact reflective and LWIR freeform precedents, not guessed from the concept render alone.

HAWK-I camera packaging

The HAWK-I optical baseline is reflective except for the entrance window, with a cold field stop at the entrance, a mirror acting as a pupil stop, filter wheels near the detector, and a mechanically stable cold structure. EmberScope uses that as a packaging lesson, not a wavelength match.

Fuerschbach 2011 LWIR freeform

A compact LWIR reflective imager at F/1.9 with a 30 mm pupil and 10 degree diagonal full field shows why freeform reflective layouts matter for uncooled microbolometer-class sensing.

Duveau 2023 asymmetric TMA

An asymmetric freeform TMA inside the same 1U volume reached 11 percent longer focal length while reporting lower freeform departure and lower orthoradial slopes than the planar-symmetric comparison case.

Druart 2022 freeform camera family

The small-field TMA and wide-field alpha-Z examples show that compact reflective cameras can preserve detector-side room for windows, filters, and even multispectral growth without giving up the freeform route.

Design rules fixed

The baseline sets constraints on alignment, manufacturability, baffling, and thermal stability before more optimization work is allowed to count as progress.

Secondary and tertiary mirror tip and tilt are treated as the most sensitive alignment degrees of freedom until a stronger tolerance study overrides that assumption. The baseline therefore prefers hard datums, subassemblies, and one controlled focus compensation step rather than many floating adjustments.

Freeform terms are allowed, but only with explicit tracking of freeform departure, orthoradial slope, mirror count, and metrology risk. Diamond-turned infrared mirrors remain the starting fabrication route, and same-material mirror and mount choices stay preferred for thermal stability.

The optical train must also carry explicit allowance for an entrance window, stops, baffling, and a practical detector-side filter stack. The current 72.0 mm source-spec package span is not treated as a licence to spend the rest of the 150 mm payload box carelessly.

Current parameter set

These are the active baseline values, but several remain provisional values awaiting detector, radiometry, and operations closure.

Topic Current baseline value Why it is still provisional
Optical family Folded compact reflective imager with three powered mirrors Higher mirror-count families remain open for comparison.
Spectral start point LWIR, 8-14 um for the first payload The LWIR/MWIR/dual-band trade keeps the first payload on the LWIR path unless later field evidence requires a two-channel upgrade.
Entrance aperture 40 mm Chosen for the present concept geometry, not from radiometry closure.
F-number F/5.0 Likely to move once detector and signal-budget work close.
Full field of view 3.0 deg provisional value tied to the current compact-layout model rather than final survey closure.
Detector provisional value Named shortlist led by `Boson+ 640 radiometric`; legacy geometry still uses 640 x 512 at 17 um pitch The detector catalogue is available, but optical exports still need to be rerun against the preferred detector branch.

What this changes

Future candidates can be compared against a stated baseline instead of a moving implied one.

The current starter-freeform train is not detector-ready. It gives EmberScope a defensible compact reflective baseline with explicit alignment and manufacturability rules.

The next comparisons should tie detector integration, radiometry, survey operations, stronger optical candidates, and higher mirror-count options to the same baseline.