# 📐 L2 Spec — Differential Interference Contrast (DIC / Nomarski) Microscopy Mismatch-Only Spec
**ID:** `L2-018-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-018`](/artifact/l1/L1-018)
> **🎯 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 | — | 0.3 – 1.49 |
| Pixel nm | nm | 50 – 300 |
| Shear nm | nm | 50 – 500 |
| Shear drift | — | 0.0 – 10.0 |
| Photon count | — | 100 – 20000 |
| Theta bias deg | deg | 30 – 150 |
| Bias retardation error | — | 0.0 – 0.15 |
| Condenser misalignment | — | 0.0 – 0.05 |
## 2. Tolerance (ε)
**Type:** `fn`
```
21.0 + 1.5 * log10(photon_count / 100) - 0.5 * shear_drift - 6.0 * bias_retardation_error
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.45 |
| Delta tier | 5 |
## 4. Fingerprint
`1307f885f0bc0b147c907279d1c087a65900d55745058683e0f5991ac223fa6e`
## 5. On-chain Registration
- **Chain hash:** `0x6a3b502a2ef2ef292154fc8f682cee861e329f3534f0f0c793c72d5d20048259`
- **Chain tx hash:** `0x32f01d93ee48f559aa137e44fb1f22b8877220f9110829c14e60ae55fb38c94d`
- **Chain block:** `41554159`
---
## File Mapping
This bundle consists of: `L2-018-001.md`, `L2-018-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-018-001.md` | Source of truth — edit this | Human or LLM |
| `L2-018-001.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 `L2-018-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._