Surface-based luminescence measurement substrate

Surface-based measurement substrate comprising:

• at least one optical cavity layer;
• a first optical mirror and a second optical mirror, the first and second optical mirrors enclosing the at least one optical cavity layer and at least partially defining an optical cavity, wherein the first optical mirror and the second optical mirror are attached and/or fixed to the at least one optical cavity layer to sandwich the at least one optical cavity layer between the first and second mirrors;
• and
• an interface layer and/or interface coating provided on the first mirror and/or the second mirror, the interface layer and/or coating being configured to receive and/or hold at least one entity comprising at least one electromagnetic radiation emitting marker;
• wherein the surface-based measurement substrate is configured for measurement of an electromagnetic radiation and/or signal emitted by and/or from at least one entity to be received and/or held on the surface-based measurement substrate, the at least one entity comprising the at least one electromagnetic radiation emitting marker configured to emit the electromagnetic radiation and/or signal when illuminated with excitation electromagnetic radiation having an excitation wavelength;
• wherein the at least one optical cavity layer is an electromagnetic radiation emitting marker-free layer and/or the optical cavity is an electromagnetic radiation emitting marker-free optical cavity, and wherein the at least one optical cavity layer defines a closed substance into which electromagnetic radiation emitting markers cannot be inserted and the optical cavity is impermeable to electromagnetic radiation emitting markers;
• and
• wherein the at least one optical cavity layer delimits a layer thickness defining at least one spectral feature and/or spectral dip in reflectance from the measurement substrate that is offset in wavelength from an emission wavelength of the at least one electromagnetic radiation emitting marker, wherein the at least one spectral feature and/or spectral dip in reflectance is indicated at a cavity resonance wavelength by an optical cavity resonance of the optical cavity, and the cavity resonance wavelength is offset in wavelength from the excitation wavelength of the excitation electromagnetic radiation that generates the electromagnetic radiation and/or signal from the at least one electromagnetic radiation emitting marker.