Orthochromatic

Okay, so when we talk about colors, we usually think of things like red, blue, green, and yellow, right? But did you know that there are some colors that you can't see? These are called ultraviolet and infrared colors, and they're too faint for your eyes to pick up.

That's where orthochromatic comes in. When we say something is orthochromatic, it means it only shows up in certain colors that we can see with our eyes. Specifically, it shows up in blue and green, but not in red.

Think of it like a special marker that only works on blue and green paper, but not on red paper. If you drew a picture with that marker on blue or green paper, it would show up great! But if you tried to draw on red paper, it wouldn't show up at all.

That's basically what orthochromatic means - it only shows up on certain types of "paper" (which in this case is the light spectrum that our eyes can see).