Writing a NK FIle

[ArielLyn43]

I need some help understanding the data types used in Indigo's NK files.

When I look at an Indigo .nk file I see 4 values on the top row and 2 columns of data. For discussion I'll define them like this:

Value A Value B Value C Value D
Column 1 Column 2
Column 1 Column 2
Column 1 Column 2

I am assuming the left column (1) is the list of refractive values N and the right column (2) is their corresponding absorption values K. But, what do the values A, B, C, and D represent? I'm guessing they define the data sample size in some way.

Any information you could share would be appreciated.

[thesquirell]

Value B and C define the min and max eV(electron volts) value. This can be also read as a wavelength, since some sheets will come with wavelengths instead of eV, and you will have to convert them. Sites like these help a lot: http://halas.rice.edu/conversions

Value A and Value D represent the scale, or the number of samples. For example, it will write something like this:

1(Value A) .5 (Value B) 6.75 (Value C) 125 (Value D)

Your min-max eV range is from .5 to 6.75. You will have 125 different eV values, 125 Column 1 and Column 2 values corresponding to that. First column is for .5 eV value, the last is for 125. If you wanna calculate the step size of eV for each sample, you could subtract Value C from Value B and divide that with total number of samples, Value D. But it is not needed, Indigo will automatically divide this for you.

That is my understanding of NK charts. Sorry if I messed somewhere up.

Here's a great site with charts:
https://www2.pvlighthouse.com.au/resour ... index.aspx

You will have to reverse the sorting, though - it is based on the wavelength value, which is reversed compared to eV (max nm=min eV)

[ArielLyn43]

That was an excellent explanation and very helpful. I really appreciate the link to the unit converter too.

Armed with your information I took another look at Indigo’s nk files. I noticed that value D was one less than the sample total and now believe it to represent the number of sample intervals. So wavelength samples less one.

I also noticed most nk files show 1 for value A, but Ingasb10.nk uses a value of 2. Ingasb10 states a low eV of .25; if we scale that by 2 it equals .5 which is in line with your minimum eV.

Hopefully adding to your contributions, I think value A is a scale applied to the eV values and value D is the number of sample intervals.

Thanks again for the help!