I've seen a Fresnel equation for calculating the reflection amount at incidence angle with n and k values defined. This formula usually comes up in relation to computer graphics, but I can't find this equation anywhere in a science context. Here is an example written in Python, taken from the websiteFresnel Formula in python:def IOR(n,k):theta_deg = 0n = nk = kfresnel = [] while theta_deg <= 90:theta = math.radians(theta_deg)a = math.sqrt((math.sqrt((n**2-k**2-(math.sin(theta))**2)**2 + ((4 * n**2) * k**2)) + (n**2 - k**2 - (math.sin(theta))**2))/2)b = math.sqrt((math.sqrt((n**2-k**2-(math.sin(theta))**2)**2 + ((4 * n**2) * k**2)) - (n**2 - k**2 - (math.sin(theta))**2))/2) Fs = (a**2+b**2-(2 * a * math.cos(theta))+(math.cos(theta))**2)/(a**2+b**2+(2 * a * math.cos(theta))+(math.cos(theta))**2)Fp = Fs * ((a**2+b**2-(2 * a * math.sin(theta) * math.tan(theta))+(math.sin(theta))**2*(math.tan(theta))**2)/(a**2+b**2+(2 * a * math.sin(theta) * math.tan(theta))+(math.sin(theta))**2*(math.tan(theta))**2))R = (Fs + Fp)/2fresnel.append(R)theta_deg += 1return fresnelI can't find any references online for this formula, the Wikipedia article on Fresnel equations contains completely different formulas, and I can't see the connection between them. I've searched high and low, but can't find any reference to this particular formula, why is that? Can you help me find it, or explain to me why I can't find it online? Or could you show me how to derive it from the Fresnel formulas from the Wikipedia article?Yes, I realize that I already have the formula right there in the code sample. But I'm baffled over why I can't find this formula anywhere, I would like to have more sources to cite then just this code example.
Fresnel equation with incident angle, n and k as input
reflection;fresnel