# 📐 L2 Spec — Talbot-Lau 3-Grating Mismatch-Only Spec
**ID:** `L2-074-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-074`](/artifact/l1/L1-074)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.68 · **Delta tier:** 5
> **⛓ On-chain block:** 41554173
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 256 – 4096 |
| W | px | 256 – 4096 |
| K steps | — | 3 – 16 |
| V center | — | 0.05 – 0.6 |
| E mean kev | — | 10.0 – 120.0 |
| Alignment tilt | — | 0.0 – 0.02 |
| Grating period um | µm | 1.0 – 10.0 |
| Phase step jitter | — | 0.0 – 0.1 |
| Grating period drift | — | 0.0 – 0.05 |
| Source coherence loss | — | 0.0 – 0.5 |
| Photon count per pixel | — | 100 – 1000000 |
## 2. Tolerance (ε)
**Type:** `fn`
```
22.0 + 2.5 * log10(photon_count_per_pixel / 100) + 15.0 * V_center - 20.0 * alignment_tilt / 0.02
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.68 |
| Delta tier | 5 |
## 4. Fingerprint
`09e0e9cb5bc24f1ca980e132bd6605256e251cddd35b8405d342afe142e9d060`
## 5. On-chain Registration
- **Chain hash:** `0xd9046e9c17b0a2befb53f1a96b82583b142ab4081b65bbaf6da231108669e961`
- **Chain tx hash:** `0x74c051943a87bcaa313304dd152bce04cc14a7cc4613aa72d79a4917acea9931`
- **Chain block:** `41554173`
---
## File Mapping
This bundle consists of: `L2-074-001.md`, `L2-074-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-074-001.md` | Source of truth — edit this | Human or LLM |
| `L2-074-001.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 `L2-074-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._