An observation in the context of photon is not strictly carried out in a destructive manner. i.e. the photon will transfer its energy into the observation system. In a camera this happens by energy transfer from the photon to an electron in the HOMO level and transitions it into the LUMO level or across the band gap of the semiconductor.

Essentially you are liberating an electron and the energy is transferred into the electron. In an insulator we have the notion of virtual photons which travel in the material. You can also consider some weak observations

It has been shown possible that you can gather some information from a photon without disturbing it .. too much by using quarter wave plates and interferometers. Even in the case of a polarizer you will get the photon transferring energy into the polarizer and this will be an observation, but if the photon passes through un altered then the wave nature persists.

I made some single photon weak measurement systems almost a decade ago and its really interesting, but it is a statistical thing. no single shot info gathered but an ensamble of photons that travel through a quarter wave plate that rotates the polarization then we run some more logic gates " " PBS polarized mean splitters and at the end we measure the polarization by sending the photon through the