AIDT 온디바이스 STEM 방사광 X선 극저온 광 파라메트릭 발진기(OPO) PPLN 준위상정합(QPM) 파장 서보 제어기

using System;
using System.Runtime.CompilerServices;

namespace ZeliDesk.Stem.OpticalParametricOscillator
{
    /// <summary>
    /// OPO 공진기 에탈론 투과 텔레메트리 상태
    /// </summary>
    public readonly ref struct OpoCavityTelemetryState
    {
        public readonly double EtalonTransmissionVoltageMv; // 에탈론 투과 오차 전압 [mV]
        public readonly double IdlerWavelengthMicrons;      // 중적외선 유휴광 파장 [um]
        public readonly double PplnCrystalTemperatureC;     // PPLN 결정 온도 [degC]
        public readonly double PumpLaserPowerWatts;         // 1064nm 펌프 파워 [W]

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public OpoCavityTelemetryState(double vEtalon, double lambdaIdler, double temp, double pPump)
        {
            EtalonTransmissionVoltageMv = vEtalon;
            IdlerWavelengthMicrons = lambdaIdler;
            PplnCrystalTemperatureC = temp;
            PumpLaserPowerWatts = pPump;
        }
    }

    /// <summary>
    /// OPO 서보 제어 명령
    /// </summary>
    public readonly ref struct OpoServoCommand
    {
        public readonly double CavityPiezoVoltageVolts;     // 공진기 PZT 전압 [V]
        public readonly double CrystalTecCurrentAmps;       // PPLN TEC 전류 [A]
        public readonly double MidIrFrequencyDriftMhz;      // 중적외선 주파수 편차 [MHz]
        public readonly bool ModeHopFreeLocked;             // 모드 홉 프리 잠금 성공 여부

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public OpoServoCommand(double vPzt, double iTec, double drift, bool locked)
        {
            CavityPiezoVoltageVolts = vPzt;
            CrystalTecCurrentAmps = iTec;
            MidIrFrequencyDriftMhz = drift;
            ModeHopFreeLocked = locked;
        }
    }

    /// <summary>
    /// 10,000Hz 주기 중적외선 OPO 파장 안정화 서보 엔진
    /// </summary>
    public ref struct OpticalParametricOscillatorServoEngine
    {
        private const double PztSensitivityMhzPerV = 8.5; // 8.5 MHz/V
        private double _accumulatedPztVolts;
        private double _accumulatedTecAmps;
        private double _prevEtalonError;

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public OpoServoCommand CalculateServoControl(
            in OpoCavityTelemetryState state, double dtSeconds)
        {
            double errorMv = state.EtalonTransmissionVoltageMv;
            double errorDiff = (dtSeconds > 1e-9) ? (errorMv - _prevEtalonError) / dtSeconds : 0.0;
            _prevEtalonError = errorMv;

            // 1. 고속 PZT 공진기 길이 제어
            _accumulatedPztVolts += 0.35 * errorMv * dtSeconds;
            _accumulatedPztVolts = Math.Clamp(_accumulatedPztVolts, -20.0, 20.0);

            double commandPzt = 60.0 + _accumulatedPztVolts + 0.05 * errorMv + 0.002 * errorDiff;
            commandPzt = Math.Clamp(commandPzt, 0.0, 120.0);

            // 2. 완만한 TEC 온도 제어 (PZT 중앙 전압 60V 유지 유도)
            double pztOffset = commandPzt - 60.0;
            _accumulatedTecAmps += 0.005 * pztOffset * dtSeconds;
            _accumulatedTecAmps = Math.Clamp(_accumulatedTecAmps, -1.5, 1.5);

            double commandTec = 1.85 + _accumulatedTecAmps;
            commandTec = Math.Clamp(commandTec, 0.0, 3.5);

            // 3. 주파수 표류량 및 잠금 판정
            double driftMhz = (commandPzt - 60.0) * PztSensitivityMhzPerV;
            bool isLocked = Math.Abs(errorMv) < 2.5;

            return new OpoServoCommand(
                commandPzt,
                commandTec,
                driftMhz,
                isLocked
            );
        }
    }
}