# 📐 L2 Spec — Second Harmonic Generation (SHG) Microscopy Mismatch-Only Spec
**ID:** `L2-021-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-021`](/artifact/l1/L1-021)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.45 · **Delta tier:** 5
> **⛓ On-chain block:** 41554171
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 128 – 2048 |
| W | px | 128 – 2048 |
| Na | — | 0.6 – 1.1 |
| Pixel nm | nm | 200 – 1000 |
| Lambda ex nm | nm | 800 – 1100 |
| Peak photons | photons | 10 – 2000 |
| Pulse width fs | — | 50 – 500 |
| Sample scattering | — | 0.0 – 0.5 |
| Quasi phase mismatch | — | 0.0 – 0.3 |
## 2. Tolerance (ε)
**Type:** `fn`
```
18.0 + 2.0 * log10(peak_photons / 10) - 8.0 * sample_scattering - 2.0 * log10(pulse_width_fs / 50)
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.45 |
| Delta tier | 5 |
## 4. Fingerprint
`babfd5058ea5b4627cc429a951531a2a047bebc1beaf471fadef670425e01b8b`
## 5. On-chain Registration
- **Chain hash:** `0xbf7fc5ac854bd66bdd5405dd6350d15fc7f44ea966220da9b2e78527be55b1c3`
- **Chain tx hash:** `0x228aee1483f92f1483cc7d55409e5c99e868247d724e8ea8140850c5830abeb0`
- **Chain block:** `41554171`
---
## File Mapping
This bundle consists of: `L2-021-001.md`, `L2-021-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-021-001.md` | Source of truth — edit this | Human or LLM |
| `L2-021-001.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 `L2-021-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._