표면증강라만산란(SERS) 핫스팟 & 1,000Hz 0-Alloc C# 국재화 표면 플라즈몬(LSPR) 서보 제어기

using System;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace ZeliDesk.Stem.NanoPlasmons
{
    /// 

    /// 분광기 1ms 라만 스펙트럼 픽셀 프레임
    /// 
    [StructLayout(LayoutKind.Sequential)]
    public readonly struct RamanPixelFrame
    {
        public readonly uint TickUs;
        public readonly float PeakRamanIntensity;  // 1330 cm^-1 라만 피크 강도 (V)
        public readonly float BaselineFluorescence;// 배경 형광 기준 전압 (V)
        public readonly float LaserIncidentPowerMw;// 785nm 레이저 출력 (mW)

        public RamanPixelFrame(uint us, float peak, float bg, float power)
        {
            TickUs = us;
            PeakRamanIntensity = peak;
            BaselineFluorescence = bg;
            LaserIncidentPowerMw = power;
        }
    }

    /// 

    /// 1,000Hz 0-Alloc SERS 단일 분자 핫스팟 능동 추적 서보 엔진
    /// 
    public ref struct SersHotspotServoEngine
    {
        private const float HotspotThresholdIntensity = 1.250f; // 핫스팟 진입 문턱 전압
        private const float TargetNetSignalVolts = 1.800f;      // 목표 순수 라만 신호

        private float _filteredNetRaman;
        private float _piezoOffsetXNm;
        private int _hotspotLockedTicks;

        public SersHotspotServoEngine(bool initialize = true)
        {
            _filteredNetRaman = 0.0f;
            _piezoOffsetXNm = 0.0f;
            _hotspotLockedTicks = 0;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool ProcessTick(in RamanPixelFrame frame, out float netRamanVolts, out float piezoDitherNm, out bool singleMoleculeTrapped)
        {
            // 1. 배경 형광 실시간 차감 (0-Alloc 스택)
            float rawNet = MathF.Max(0.0f, frame.PeakRamanIntensity - frame.BaselineFluorescence);

            // 2. 지수 이동 평균 평활화
            _filteredNetRaman = (0.3f * rawNet) + (0.7f * _filteredNetRaman);
            netRamanVolts = _filteredNetRaman;

            // 3. 단일 분자 핫스팟 포획 판정
            if (_filteredNetRaman >= HotspotThresholdIntensity)
            {
                _hotspotLockedTicks++;
                singleMoleculeTrapped = (_hotspotLockedTicks >= 3);
            }
            else
            {
                _hotspotLockedTicks = Math.Max(0, _hotspotLockedTicks - 1);
                singleMoleculeTrapped = false;
            }

            // 4. 극대 신호 탐색을 위한 나노 디더링 (Extremum Seeking Dither)
            float error = TargetNetSignalVolts - _filteredNetRaman;
            _piezoOffsetXNm += Math.Clamp(error * 2.5f, -15.0f, 15.0f);
            _piezoOffsetXNm = Math.Clamp(_piezoOffsetXNm, -200.0f, 200.0f);

            piezoDitherNm = _piezoOffsetXNm;
            return singleMoleculeTrapped;
        }
    }
}