[jlokier]

An iPhone will not produce 670nm narrow band light.

Here are measured spectra for iPhone X and iPad Air 2 respectively:

    http://www.displaymate.com/Spectra_41a.html
    http://www.displaymate.com/Spectra_35.html

As you can see, although there is some energy at 670nm, there is much more energy at shorter wavelengths (~620-630nm peak) from the screen's red emitter. You can't change the red emitter's spectrum (the rightmost peak in those charts), you can only change the relative height of the three peaks to change perceived colour.

So you can't make a spectrum containing a single peak around 670nm.

[eatbitseveryday]

Just a note, you are indenting your urls making HN use code formatting on them, thus rendering them not clickable. just paste the url itself without indent.

[jlokier]

Noted, thanks. I think they look better in code formatting, but forgot about clickability.