The 454 GS Junior Camera

The 454 GS Junior has no optical system to speak of. The 454 approach didn’t use fluorescence, so there no excitation light that needs to be delivered to the flowcell (like the HiSeq for example). Here an enzyme (luciferase) is used to generate light when nucleotides are incorporated.

You could I imagine use a traditional microscope to image this. Instead 454 opted to use a contact imaging approach (like the iSeq). But unlike the iSeq the imaging sensor isn’t disposable here.

So they needed a way to transport light from the flowcell to the imaging sensor.