Can they tell it's an illusion?
An illusionist can tell that a physical illusion she created is an illusion, because she created it.
In the same manner someone in our modern world could look at an image they had altered with photoshop (or a similar program) and know that it was 'shopped not because of the image's content, but because they personally made the changes to the image, even if someone else would have great difficulty deducing that the image had been altered.
What's the difference between Physical and Mana illusions?
It's worth noting here that what we 'see' is just an image our minds construct based on photons (particles of light) hitting the retinas in our eyes.
A physical illusion alters the photons in the world itself, this is why all imaging systems (biological and technological) pick up the illusion and convey that message to the brain or computer system connected to them.
With Mana illusions think of it as applying special effects directly to the image the brain produces, the eye doesn't see the bugs in a Swarm spell (because they don't exist) but your spell edits the image the brain produces to add the bugs in afterwards. Since a security camera is not connected to a living brain, mana illusions have no effect on the image it records.
What does that mean for this question?
Whether or not you argue that this allows the caster to literally see through mana illusions is up to you and your GM. The rules state that 'you are unaffected' but whether this means you simply know the illusion to be false or cannot see it at all is not clearly stated.
However as this refers to physical illusions the answer is clear, your spell alters the photons that are bouncing around the world. Your brain can't separate these photons from any others and thus any invisible person or illusory wall appears (even to the caster) exactly as the illusion spell intends it to.
How does this affect Improved Invisibility specifically?
It's worth noting that the caster of an Improved Invisibility spell must consciously sustain the spell in order for it to remain active, it therefore makes sense that they have an innate knowledge of where the target of this spell is. In short, for as long as they sustain that spell they can't see them (because their eyes can't possibly pick them up) but they would almost certainly still know where they were. Astral Perception may also allow them to see the aura produced by their spell and thus somewhat 'see' the invisible person.