Swept, confocally-aligned, planar excitation (SCAPE) microscopy using a graded-index (GRIN) lens

An imaging apparatus comprising:

• a first set of optical components having a proximal end and a distal end, wherein the first set of optical components includes a first objective disposed at the distal end of the first set of optical components;
• a GRIN lens positioned distally beyond the first objective;
• a second set of optical components having a proximal end and a distal end, wherein the second set of optical components includes a second objective disposed at the distal end of the second set of optical components;
• a scanning element that is disposed proximally with respect to the proximal end of the first set of optical components and proximally with respect to the proximal end of the second set of optical components;
• wherein the scanning element is positioned to route a sheet of excitation light so that the sheet of excitation light will pass in a proximal to distal direction through the first set of optical components and through the GRIN lens, and project into a sample that is positioned distally beyond the GRIN lens, wherein the sheet of excitation light is projected into the sample at an oblique angle with respect to an optical axis of the first objective, and wherein the sheet of excitation light is projected into the sample at a position that varies depending on an orientation of the scanning element,
• wherein the GRIN lens and the first set of optical components route detection light from the sample in a distal to proximal direction back to the scanning element, and
• wherein the scanning element is also positioned to route the detection light so that the detection light will pass through the second set of optical components in a proximal to distal direction and form an oblique intermediate image plane at a position that is distally beyond the distal end of the second set of optical components;
• and
• a third objective with an associated optical interface that are collectively positioned to route light that arrives at the oblique intermediate image plane towards a camera, wherein the third objective and the associated optical interface are collectively configured to provide a zero working distance to maximize detection NA,
• wherein the second objective is an air objective and the third objective is a non-air immersion objective, and
• wherein the associated optical interface comprises a cured polymer spacer having a refractive index that matches an immersion medium of the third objective, wherein the cured polymer spacer is affixed directly to a front surface of the third objective.