AIDT 온디바이스 STEM 유도 라만 산란(SRS) 고주파 록인 비디오 서보 엔진

using System;
using System.Runtime.CompilerServices;

namespace ZeliDesk.Stem.Srs
{
    public readonly ref struct SrsPixelState
    {
        public readonly double StimulatedRamanLossRatio; // SRL 변조율 Delta Ip / Ip (10^-5)
        public readonly double LockInDemodulatedV;      // 록인 복조 전압 (uV)
        public readonly double ProteinConcentration;     // 단백질 신호 강도 (2930 cm^-1)
        public readonly double LipidConcentration;       // 지질 신호 강도 (2845 cm^-1)
        public readonly double TumorProbability;         // 암세포 판정 확률 (0.0~1.0)
        public readonly double LaserShotNoiseLimitedSnr; // 샷 잡음 한계 SNR (dB)

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public SrsPixelState(double srl, double vLock, double protein, double lipid, double tumor, double snr)
        {
            StimulatedRamanLossRatio = srl;
            LockInDemodulatedV = vLock;
            ProteinConcentration = protein;
            LipidConcentration = lipid;
            TumorProbability = tumor;
            LaserShotNoiseLimitedSnr = snr;
        }
    }

    public ref struct SrsImagingEngine
    {
        private const double ECharge = 1.602176634e-19;

        private readonly double _modulationFreqMhz;     // EOM 변조 주파수 (MHz, 예: 20 MHz)
        private double _pumpPowerMw;                    // 펌프 빔 파워 (mW)
        private double _stokesPowerMw;                  // 스톡스 빔 파워 (mW)

        public SrsImagingEngine(double modMhz = 20.0, double pumpMw = 25.0, double stokesMw = 50.0)
        {
            _modulationFreqMhz = modMhz;
            _pumpPowerMw = pumpMw;
            _stokesPowerMw = stokesMw;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public SrsPixelState StepServo(double rawPhotodiodeCurrentMa, double demodPhaseDeg, double lipidRamanFactor, double proteinRamanFactor, double dtSec)
        {
            // 1. 순수 선형 분자 농도 비례 SRL 계산 (Delta Ip / Ip)
            // Delta Ip = -alpha * N * Ip * Is
            double totalCross = (lipidRamanFactor * 1.2 + proteinRamanFactor * 0.9);
            double srlRatio = totalCross * (_stokesPowerMw / 50.0) * 2.5e-5; // 2.5 x 10^-5 수준

            // 2. 20MHz 록인 위상 정합 복조 전압 (uV)
            double phaseRad = demodPhaseDeg * Math.PI / 180.0;
            double vLockInUv = srlRatio * 1e6 * Math.Max(Math.Cos(phaseRad), 0.0);

            // 3. 광자 샷 잡음 한계 SNR (dB) 계산
            // I_noise = sqrt(2 * e * I_dc * Delta_f)
            double iDc = rawPhotodiodeCurrentMa * 1e-3;
            double shotNoise = Math.Sqrt(2.0 * ECharge * iDc * 100000.0); // 100 kHz 대역폭
            double signalCurrent = iDc * srlRatio;
            double snrDb = (signalCurrent > shotNoise) ? 20.0 * Math.Log10(signalCurrent / shotNoise) : 0.0;

            // 4. 단백질 대 지질 비를 통한 뇌종양 세포 침윤 확률 판정
            // 종양 조직은 세포 밀도가 높아 단백질 신호가 급증하고 미엘린 지질 신호가 급감 (CH3 / CH2 ratio 증가)
            double lipidSignal = lipidRamanFactor * 100.0;
            double proteinSignal = proteinRamanFactor * 100.0;
            double proteinLipidRatio = proteinSignal / Math.Max(lipidSignal, 1.0);
            double tumorProb = Math.Clamp((proteinLipidRatio - 1.2) / 2.0, 0.0, 1.0);

            return new SrsPixelState(
                srl: srlRatio * 1e5,
                vLock: vLockInUv,
                protein: proteinSignal,
                lipid: lipidSignal,
                tumor: tumorProb,
                snr: snrDb
            );
        }
    }
}