# ⚛  L1 Principle — Pump-Probe Spectroscopy / Imaging

**ID:** `L1-150` · **Status:** ⊙ Testnet (genesis catalog)

> **🌐 Domain:** Ultrafast Imaging — *Femtosecond two-pulse transient imaging*
> **🎯 Problem class:** nonlinear inverse · **🧮 Solution space:** 2D transient absorption
> **📡 Carrier:** photon · **🌫 Noise:** gaussian
> **⚖ Difficulty (δ):** 5 · **⛓ Block:** 41554229

---

## 🧠 1. Introduction

**Pump-Probe Spectroscopy / Imaging** is a **nonlinear inverse problem** whose unknown lives in **2D transient absorption** space, within the **Femtosecond two-pulse transient imaging** sub-domain of **Ultrafast Imaging**.

Measurements consist of photons collected by an optical detector via a **pump probe transient** sensing mechanism.

The forward operator applies, in order: L · pump pulse operator; L · probe pulse operator; L · delay stage operator; detector accumulates flux over the exposure window.

Observations are corrupted by additive Gaussian noise. Existence of the recovered 2D transient absorption is guaranteed within the declared Omega bounds. Uniqueness is local rather than global (non-convex landscape); convergence depends on initialisation and priors. Stability is moderately conditioned (kappa_eff ~= 14); pulse_jitter dominates the stability cliff; delay_stage_drift and the remaining mismatch parameters contribute higher-order bias terms. Additive gaussian thermal/electronic noise sets the irreducible data-fidelity floor, while mild Tikhonov or analytic inversion is sufficient at the nominal Omega point.

## ⚙ 2. Forward Model

Physical chain: **x** → L · pump pulse → L · probe pulse → L · delay stage → Temporal integration → **y** (detector).

```
y = ∫_t dt `L.delay_stage` `L.probe_pulse` `L.pump_pulse` x + n,    n ~ 𝒩(0, σ²)
```

**Measurement DAG:**

| Primitive | What it does |
|---|---|
| `L.pump_pulse` | L · pump pulse operator |
| `L.probe_pulse` | L · probe pulse operator |
| `L.delay_stage` | L · delay stage operator |
| `int.temporal` | Detector accumulates flux over the exposure window |

## 🔬 3. Physics Fingerprint

| Property | Value |
|---|---|
| Domain | Ultrafast Imaging |
| Sub domain | Femtosecond two-pulse transient imaging |
| Carrier | photon |
| Problem class | nonlinear_inverse |
| Solution space | 2D_transient_absorption |
| Noise model | gaussian |
| Integration axis | temporal |
| Difficulty delta | 5 |
| L dag | 3.5 |

## 📡 4. Measurement Model

Existence of the recovered 2D transient absorption is guaranteed within the declared Omega bounds. Uniqueness is local rather than global (non-convex landscape); convergence depends on initialisation and priors. Stability is moderately conditioned (kappa_eff ~= 14); pulse_jitter dominates the stability cliff; delay_stage_drift and the remaining mismatch parameters contribute higher-order bias terms. Additive gaussian thermal/electronic noise sets the irreducible data-fidelity floor, while mild Tikhonov or analytic inversion is sufficient at the nominal Omega point.

| Metric | Value |
|---|---|
| Metric | PSNR_dB |
| Secondary | SSIM |

## 📏 5. Operating Range (Ω)

**Center problem class:** `pump_probe` · **Forward operator:** `pump_probe_forward`

**Center point:**

| Parameter | Unit | Value |
|---|---|---|
| N delays | — | 256 |
| Pulse fs | — | 50 |
| Photon count | — | 1000 |
| Pulse jitter | — | 0 |
| N wavelengths | — | 512 |
| Thermal drift | — | 0 |
| Delay stage drift | — | 0 |
| Two color overlap | — | 1 |

**Allowed bounds:**

| Parameter | Unit | Range |
|---|---|---|
| N delays | — | 32 – 2048 |
| Pulse fs | — | 10 – 500 |
| Photon count | — | 50 – 10000 |
| Pulse jitter | — | 0.0 – 50.0 |
| N wavelengths | — | 64 – 4096 |
| Thermal drift | — | 0.0 – 0.3 |
| Delay stage drift | — | 0.0 – 5.0 |
| Two color overlap | — | 0.3 – 1.0 |

## 🎯 6. Tolerance (ε)

**Center tolerance:** 24.0

| Metric | Range |
|---|---|
| Psnr db | 5.0 – 40.0 |

## ⚖ 7. Hardness Function

Hardness scales as **`epsilon_fn`** on **PSNR_dB**, with κ = `280` and δ = `5`.

## 💾 8. Reference Dataset

- **primary** · weight 1.0 · IPFS _(not pinned yet)_

## 9. On-chain Registration

- **Chain hash:** `0x7c8274a2f2c863172af0fa6ffe8668fc1fc1760508c60443049892556c9a69bc`
- **Chain tx hash:** `0x620ddcb4a1584ab2dfd0ac6d41a6a63658a309e58b556e997341418bf6ceb29c`
- **Chain block:** `41554229`

---

## File Mapping

This bundle consists of: `L1-150.md`, `L1-150.json`.

| File | Role | How to regenerate |
|------|------|-------------------|
| `L1-150.md` | Source of truth — edit this | Human or LLM |
| `L1-150.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 `L1-150`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._