초고해상도 방사광 가속기(Synchrotron) X선 간섭계 & 1,000Hz 0-Alloc C# 보어만(Borrmann) 비대칭 회절 위상 영상화 엔진

using System;
using System.Runtime.CompilerServices;

namespace ZeliDesk.Stem.SynchrotronOptics;

/// 

/// 방사광 X선 위상 간섭계 상태 구조체 (100% Stack Allocation)
/// 
public readonly ref struct XrayInterferometerState
{
    public readonly double PhaseShiftRadian;      // 측정된 X선 위상차 (rad)
    public readonly double InterferenceIntensity; // 정규화 간섭 광도 (a.u.)
    public readonly double FringeVisibility;      // 간섭 무늬 선명도 (0~1)
    public readonly double ReconstructedDelta;    // 복원된 굴절률 결손치 δ
    public readonly double ContrastGainFactor;    // 흡수 대비 위상차 조영 증폭비
    public readonly double PiezoShiftNm;          // 피에조 위상 시프터 변위 (nm)

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public XrayInterferometerState(
        double phaseShiftRadian,
        double interferenceIntensity,
        double fringeVisibility,
        double reconstructedDelta,
        double contrastGainFactor,
        double piezoShiftNm)
    {
        PhaseShiftRadian = phaseShiftRadian;
        InterferenceIntensity = interferenceIntensity;
        FringeVisibility = fringeVisibility;
        ReconstructedDelta = reconstructedDelta;
        ContrastGainFactor = contrastGainFactor;
        PiezoShiftNm = piezoShiftNm;
    }
}

/// 

/// 1,000Hz 0-Alloc C# 방사광 가속기 단결정 실리콘 X선 위상 간섭 시뮬레이터
/// 
public static class SynchrotronXrayEngine
{
    private const double XrayWavelengthM = 0.71e-10;  // 17.5 keV Mo-Ka 상당 (0.071 nm)
    private const double DeltaWater = 7.15e-7;        // 17.5 keV에서 물의 δ
    private const double BetaWater = 2.45e-10;        // 17.5 keV에서 물의 β (흡수 항)

    /// 

    /// 1ms 타임스텝 3단계 위상 천이 기반 위상차 및 굴절률 복원 연산 (0-Alloc)
    /// 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static XrayInterferometerState StepPhaseRetrieval(
        double intensity0,
        double intensity120,
        double intensity240,
        double sampleThicknessMicron,
        double piezoShiftNm)
    {
        // 1. 3단계 위상 천이(Three-step phase-shift) 알고리즘: tan(phi) = sqrt(3)*(I240 - I120) / (2*I0 - I120 - I240)
        double num = Math.Sqrt(3.0) * (intensity240 - intensity120);
        double den = 2.0 * intensity0 - intensity120 - intensity240;
        double phaseRad = Math.Atan2(num, den);

        // 2. 간섭 무늬 선명도(Visibility) 계산
        double iMax = Math.Max(intensity0, Math.Max(intensity120, intensity240));
        double iMin = Math.Min(intensity0, Math.Min(intensity120, intensity240));
        double visibility = (iMax + iMin) > 0.0 ? (iMax - iMin) / (iMax + iMin) : 0.0;

        // 3. 굴절률 결손치 δ 역산: ΔΦ = (2π / λ) * δ * t
        double thicknessMeters = sampleThicknessMicron * 1e-6;
        double reconstructedDelta = thicknessMeters > 0.0 ? (Math.Abs(phaseRad) * XrayWavelengthM) / (2.0 * Math.PI * thicknessMeters) : 0.0;

        // 4. 위상 콘트라스트 대 흡수 콘트라스트 증폭비 (δ / β)
        double contrastGain = DeltaWater / BetaWater; // 약 2,900배

        return new XrayInterferometerState(
            phaseRad,
            intensity0,
            visibility,
            reconstructedDelta,
            contrastGain,
            piezoShiftNm);
    }
}