To see, means to consciously perceive, unlike detect, which is a mechanical process, which requires no consciousness. A infrared camera can detect light, but it sees nothing. We, humans, see a representation of reality. As answered by my question, "Do we really see objects?", we perceive our brains representation of objects, not the objects themselves. But what of light? Do we see actual electromagnetic radiation, or do we perceive brightness, because of light?
Basically, your question concerns the content of perception ("what we perceive"). As explained here, "content" can be understood in two senses, as in "the content of a bucket" or "the content of a story". You seem to imply the first sense in your question, where the content of perception would be "what is in the mind when we perceive something" (you say "our brains representation of objects"). Some philosophers hold this view as well, but there are reasons to think that the second sense is more appropriate, where, so to speak, perceiving is representing something outside (and it's not, literally speaking, the brain that represents, but the perceiving agent). In this second sense, the content of perception is, as in "content of a story", some external state of affairs, and it is closely related to belief. As explained in the entry linked above, there are reasons to adopt this understanding if one accepts that perception can be falsidical (we see a fish, but there's no fish).
In this view, we perceive (=represent) external objects directly. This does not mean that we perceive them "as they are" though.
Applied to light, there's a further step because even if we perceive "brightness" (conceived of as an external, objective state of affairs) this does not mean that we perceive "electromagnetic radiations" (or their amplitude). The further step is a reductionist account that would entail that brightness just is (amplitude of) electromagnetic radiation. But once the first step is assumed, this question is just a question of reduction and is independent of perception and less problematic.
Now you can still deny that perception has content in the "story" sense, and distinguish perception and judgement, as some philosophers do. Then perhaps we do not perceive electromagnetic radiations. You can find references in the entry linked above.
Some light is detectable, but no light is visible. Visible is a term used to describe the conscious perception of visual representations within our brains visual cortex. Trees, people, words on a page, are all visible. Air is invisible. We see trees, people and words on a page, but we can't see air. Light is the reason we see things. When our eyes detect light, our brain creates visual representations of the objects from which the light originates. We see these representations. It's illogical to say we see light as light exists outside of our subjective reality.
There is contention amongst physicists as to whether we perceive an object or only see the light (electromagnetic radiation) which the object emits. I propose that we see neither. Visual perception occurs in the visual cortex. What we see is neither the actual object, nor light, but a visual representation of the object.
Visual perception is a process, of which, detecting electromagnetic radiation is but a part. The actual perception occurs at the end of the process.