fix computation of delta_n_abs

heterophyllus · Aug 28, 2022 · abb6f61 · abb6f61
1 parent 5902277
commit abb6f61
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Showing 5 changed files with 33 additions and 20 deletions.
diff --git a/data/Schott.xlsx b/data/Schott.xlsx
diff --git a/src/air.cpp b/src/air.cpp
@@ -29,16 +29,16 @@ double Air::refractive_index_abs(double lambdamicron, double T, double P)
 {
     constexpr double P0 = 101325.0;
     constexpr double Tref = 15;
-    double nref = refractive_index_ref(lambdamicron);
+    double nref = refractive_index_15degC_1atm(lambdamicron);
     double num = nref - 1.0;
     double denom = 1.0 + (T-Tref)*(3.4785*pow(10,-3));
 
     return ( 1.0 + (num/denom)*(P/P0) );
 }
 
-double Air::refractive_index_ref(double lambdamicron)
+double Air::refractive_index_15degC_1atm(double lambdamicron)
 {
-    double term1 = 6432.8;
+    constexpr double term1 = 6432.8;
     double term2 = 2949810.0*pow(lambdamicron, 2)/( 146.0*pow(lambdamicron,2) - 1.0 );
     double term3 = 25540.0*pow(lambdamicron,2)/( 41.0*pow(lambdamicron,2) - 1.0 );
     double nref = 1.0 + (term1 + term2 + term3)*pow(10, -8);

diff --git a/src/air.h b/src/air.h
@@ -33,7 +33,7 @@ class Air
     static double refractive_index_abs(double lambdamicron, double T, double P= 101325.0);
 
     /** Computes refractive index at the reference temperature */
-    static double refractive_index_ref(double lambdamicron);
+    static double refractive_index_15degC_1atm(double lambdamicron);
 };
 
 #endif // AIR_H
diff --git a/src/glass.cpp b/src/glass.cpp
@@ -135,7 +135,7 @@ double Glass::Pxy_(const QString& x, const QString& y) const
 
 double Glass::refractiveIndex(double lambdamicron) const
 {
-    return refractiveIndex_rel(lambdamicron);
+    return refractiveIndex_rel(lambdamicron, T_);
 }
 
 double Glass::refractiveIndex(const QString& spectral) const
@@ -145,7 +145,7 @@ double Glass::refractiveIndex(const QString& spectral) const
 
 QVector<double> Glass::refractiveIndex(const QVector<double> &vLambdamicron) const
 {
-    return refractiveIndex_rel(vLambdamicron);
+    return refractiveIndex_rel(vLambdamicron, T_);
 }
 
 double Glass::refractiveIndex_rel_Tref(double lambdamicron) const
@@ -167,12 +167,11 @@ double Glass::refractiveIndex_abs_Tref(double lambdamicron) const
     return n_abs_T0;
 }
 
-double Glass::refractiveIndex_abs(double lambdamicron) const
+double Glass::refractiveIndex_abs(double lambdamicron, double T) const
 {
     double dn = 0.0;
     if(hasThermalData_){
-        double dn_dt = dn_dt_abs(T_, lambdamicron);
-        dn = (T_-Tref_)*dn_dt;
+        dn = delta_n_abs(T, lambdamicron);
     }
 
     double n_abs_T0 = refractiveIndex_abs_Tref(lambdamicron);
@@ -181,10 +180,10 @@ double Glass::refractiveIndex_abs(double lambdamicron) const
     return n_abs;
 }
 
-double Glass::refractiveIndex_rel(double lambdamicron) const
+double Glass::refractiveIndex_rel(double lambdamicron, double T) const
 {
-    double n_abs = refractiveIndex_abs(lambdamicron);
-    double n_air = Air::refractive_index_abs(lambdamicron, T_);
+    double n_abs = refractiveIndex_abs(lambdamicron, T);
+    double n_air = Air::refractive_index_abs(lambdamicron, T);
     double n_rel = n_abs/n_air;
 
     return n_rel;
@@ -204,13 +203,13 @@ QVector<double> Glass::refractiveIndex_rel_Tref(const QVector<double>& vLambdami
 }
 
 
-QVector<double> Glass::refractiveIndex_rel(const QVector<double> &vLambdamicron) const
+QVector<double> Glass::refractiveIndex_rel(const QVector<double> &vLambdamicron, double T) const
 {
     const int dataCount = vLambdamicron.size();
     QVector<double> n_rel_v(dataCount);
 
     for(int i = 0; i < dataCount; i++){
-        n_rel_v[i] = refractiveIndex_rel(vLambdamicron[i]);
+        n_rel_v[i] = refractiveIndex_rel(vLambdamicron[i], T);
     }
 
     return n_rel_v;
@@ -452,11 +451,9 @@ void Glass::appendTransmittanceData(double lambdamicron, double trans, double th
 double Glass::dn_dt_abs(double T, double lambdamicron) const
 {
     double dT = T - Tref_;
-    double Stk = (Ltk() > 0.0) - (Ltk() < 0.0);
     double n  = refractiveIndex_abs_Tref(lambdamicron);
 
-    //return (n*n-1)/(2*n) * ( D0() + 2*D1()*dT + 3*D2()*dT*dT + (E0() + 2*E1()*dT)/(lambdamicron*lambdamicron - Ltk()*Ltk()) );
-    return (n*n-1)/(2*n) * ( D0() + 2*D1()*dT + 3*D2()*dT*dT + (E0() + 2*E1()*dT)/(lambdamicron*lambdamicron - Stk*Ltk()*Ltk()) );
+    return (n*n-1)/(2*n) * ( D0() + 2*D1()*dT + 3*D2()*dT*dT + (E0() + 2*E1()*dT)/(lambdamicron*lambdamicron - Ltk()*Ltk()) );
 }
 
 QVector<double> Glass::dn_dt_abs(const QVector<double>& vT, double lambdamicron) const
@@ -471,6 +468,20 @@ QVector<double> Glass::dn_dt_abs(const QVector<double>& vT, double lambdamicron)
     return vDndt;
 }
 
+
+double Glass::delta_n_abs(double T, double lambdamicron) const
+{
+    double dT = T - Tref_;
+    double Stk = (Ltk() > 0.0) - (Ltk() < 0.0);
+    double n  = refractiveIndex_rel_Tref(lambdamicron);
+
+    // Schott technical document
+    return (n*n-1)/(2*n) * ( D0()*dT+ D1()*dT*dT + D2()*dT*dT*dT + (E0()*dT + E1()*dT*dT)/(lambdamicron*lambdamicron - Ltk()*Ltk()) );
+
+    // Zemax manual
+    //return (n*n-1)/(2*n) * ( D0()*dT+ D1()*dT*dT + D2()*dT*dT*dT + (E0()*dT + E1()*dT*dT)/(lambdamicron*lambdamicron - Stk*Ltk()*Ltk()) );
+}
+
 void Glass::setThermalData(int n, double val)
 {
     Q_ASSERT( thermal_data_size_ == thermal_data_.size() );

diff --git a/src/glass.h b/src/glass.h
@@ -101,6 +101,8 @@ class Glass
     double          dn_dt_abs(double T, double lambdamicron) const;
     QVector<double> dn_dt_abs(const QVector<double>& vT, double lambdamicron) const;
 
+    double delta_n_abs(double T, double lambdamicron) const;
+
     inline void setHasThermalData(bool state);
     void setThermalData(int n, double val);
 
@@ -135,10 +137,10 @@ class Glass
 private:
     double          refractiveIndex_abs_Tref(double lambdamicron) const;
     double          refractiveIndex_rel_Tref(double lambdamicron) const;
-    double          refractiveIndex_abs(double lambdamicron) const;
-    double          refractiveIndex_rel(double lambdamicron) const;
+    double          refractiveIndex_abs(double lambdamicron, double T) const;
+    double          refractiveIndex_rel(double lambdamicron, double T) const;
     QVector<double> refractiveIndex_rel_Tref(const QVector<double>& vLambdamicron) const;
-    QVector<double> refractiveIndex_rel(const QVector<double>& vLambdamicron) const;
+    QVector<double> refractiveIndex_rel(const QVector<double>& vLambdamicron, double T) const;
 
     /** current temperature */
     static double T_;