# 📐 L2 Spec — Photoacoustic Tomography (PAT) Mismatch-Only Spec
**ID:** `L2-041-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-041`](/artifact/l1/L1-041)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.5 · **Delta tier:** 5
> **⛓ On-chain block:** 41552979
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 64 |
| W | px | 64 |
| Z | — | 16 – 512 |
| Snr db | dB | 0.0 – 35.0 |
| Lambda nm | nm | 650 – 1064 |
| N transducers | — | 32 – 1024 |
| Coupling medium | — | 0.0 – 0.3 |
| Limited view geometry | — | 0.0 – 0.6 |
| Laser fluence variation | — | 0.0 – 0.3 |
| Sound speed heterogeneity | — | 0.0 – 0.05 |
## 2. Tolerance (ε)
**Type:** `fn`
```
15.0 + 0.3 * SNR_dB - 20.0 * sound_speed_heterogeneity - 6.0 * limited_view_geometry - 5.0 * laser_fluence_variation
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.5 |
| Delta tier | 5 |
## 4. Fingerprint
`bd34acd1d30bf7b1099264dfd66aac5686a15eab53941bb91786f036df432c8c`
## 5. On-chain Registration
- **Chain hash:** `0x261c7638cf25376f033162cdd46c5a6ea2f903d749086791d56b5b83fdeade43`
- **Chain tx hash:** `0x54c0b226f4f59ae6e9ed03f72fa3826496f190621570d1f13c17285a29e346aa`
- **Chain block:** `41552979`
---
## File Mapping
This bundle consists of: `L2-041-001.md`, `L2-041-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-041-001.md` | Source of truth — edit this | Human or LLM |
| `L2-041-001.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 `L2-041-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._