You don't need a frequency sweep. You take three broad spectrum lights and ask people to adjust their brightnesses to match a selection of reference lights. The

You don't need a frequency sweep. You take three broad spectrum lights and ask people to adjust their brightnesses to match a selection of reference lights. The tool that does this is called an anomaloscope and it was invented before things like lasers in order to study how color vision worked. That work became the basis of CIE (and other standards) that now define how your screen renders accurate colors. This setup is straightforward to adjust to different types of color vision too. They use 3 lights because that's how many opsins normal humans use for color vision. If you're testing di- or tetrachromats you can use 2 or 4 lights respectively, or 12 if you're testing intelligent mantis shrimp.