AIDT 온디바이스 STEM 방사광 X선 극저온 광 파라메트릭 처프 펄스 증폭(OPCPA) 타이밍 지터 서보 제어기

using System;
using System.Runtime.CompilerServices;

namespace ZeliDesk.Stem.OpcpaTiming
{
    /// <summary>
    /// BOC 상호상관기 텔레메트리 계측 상태
    /// </summary>
    public readonly ref struct BocCrossCorrelatorTelemetryState
    {
        public readonly double BocDetectorVoltageMv;     // BOC 검출기 차동 출력 전압 [mV]
        public readonly double AmplifiedSignalPowerMw;   // 증폭된 신호광 출력 [mW]
        public readonly double PumpSeedOverlapRatio;     // 공간-시간 중첩률 (0~1)
        public readonly double BboCrystalTempKelvin;     // BBO 결정 온도 [K]

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public BocCrossCorrelatorTelemetryState(double vBoc, double pSignal, double overlap, double temp)
        {
            BocDetectorVoltageMv = vBoc;
            AmplifiedSignalPowerMw = pSignal;
            PumpSeedOverlapRatio = overlap;
            BboCrystalTempKelvin = temp;
        }
    }

    /// <summary>
    /// 광학 지연선 피에조 제어 명령
    /// </summary>
    public readonly ref struct OpcpaDelayServoCommand
    {
        public readonly double DelayPiezoVoltageVolts;   // 피에조 지연선 전압 [V]
        public readonly double ResidualTimingJitterFs;   // 잔여 타이밍 지터 [fs]
        public readonly double AmplificationGainRatio;   // 달성된 증폭 이득비
        public readonly bool TimingSynchronized;         // 10fs 이내 동기화 잠금 여부

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public OpcpaDelayServoCommand(double vPzt, double jitter, double gain, bool locked)
        {
            DelayPiezoVoltageVolts = vPzt;
            ResidualTimingJitterFs = jitter;
            AmplificationGainRatio = gain;
            TimingSynchronized = locked;
        }
    }

    /// <summary>
    /// 10,000Hz 주기 OPCPA 광-광 타이밍 지터 서보 엔진
    /// </summary>
    public ref struct OpcpaTimingJitterServoEngine
    {
        private const double BocSensitivityMvPerFs = 4.2; // 4.2 mV/fs
        private const double PiezoScaleFsPerVolt = 25.0;  // 1V당 25fs 지연
        private double _accumulatedPztVolts;
        private double _prevBocError;

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public OpcpaDelayServoCommand UpdateServo(
            in BocCrossCorrelatorTelemetryState state, double dtSeconds)
        {
            double timingErrorFs = state.BocDetectorVoltageMv / BocSensitivityMvPerFs;
            double errorDiff = (dtSeconds > 1e-9) ? (timingErrorFs - _prevBocError) / dtSeconds : 0.0;
            _prevBocError = timingErrorFs;

            // PI 폐루프 적분
            _accumulatedPztVolts += (0.85 * timingErrorFs / PiezoScaleFsPerVolt) * dtSeconds;
            _accumulatedPztVolts = Math.Clamp(_accumulatedPztVolts, -15.0, 15.0);

            double commandPzt = 50.0 + _accumulatedPztVolts + (0.15 * timingErrorFs / PiezoScaleFsPerVolt) + 0.002 * errorDiff;
            commandPzt = Math.Clamp(commandPzt, 0.0, 100.0);

            double residualJitter = Math.Abs(timingErrorFs);
            bool isLocked = residualJitter < 10.0; // 10fs 이내 수렴

            double gainRatio = isLocked ? 45000.0 : 1200.0;

            return new OpcpaDelayServoCommand(commandPzt, residualJitter, gainRatio, isLocked);
        }
    }
}