# 📐 L2 Spec — Darkfield Microscopy (oblique-illumination scattering imaging) Mismatch-Only Spec
**ID:** `L2-019-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-019`](/artifact/l1/L1-019)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.45 · **Delta tier:** 5
> **⛓ On-chain block:** 41554159
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 256 – 4096 |
| W | px | 256 – 4096 |
| Na obj | — | 0.3 – 1.3 |
| Na cond | — | 0.6 – 1.4 |
| Pixel nm | nm | 100 – 500 |
| Stray light | — | 0.0 – 0.2 |
| Photon count | — | 50 – 10000 |
| Specimen absorption | — | 0.0 – 0.5 |
| Condenser angle error | — | 0.0 – 0.05 |
## 2. Tolerance (ε)
**Type:** `fn`
```
21.0 + 1.5 * log10(photon_count / 50) - 8.0 * stray_light - 2.0 * specimen_absorption
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.45 |
| Delta tier | 5 |
## 4. Fingerprint
`a65b621dfbe4ccd0c807d6fc4fd7c93ccfb793da9411e14db03b1bc23f92b45b`
## 5. On-chain Registration
- **Chain hash:** `0xc7893a906eb1d332a1baee2f3357f92cb71485256e33f5feab35ad7465c61d58`
- **Chain tx hash:** `0x6c4d8b67a38051e14677856e12d8e1e056b11ebfc4d992acf8f3ddbf5a13940b`
- **Chain block:** `41554159`
---
## File Mapping
This bundle consists of: `L2-019-001.md`, `L2-019-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-019-001.md` | Source of truth — edit this | Human or LLM |
| `L2-019-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |
**Prompt for your LLM after editing this Markdown:**
> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.
_This Markdown was auto-synthesized from the catalog row for `L2-019-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._