Abstract: A miniaturized microscope having a tunable focal length provides for fluorescence measurements at an adjustable focus, providing for autofocus and/or depth adjustment of an image measurement without altering or adjusting a probe implanted in a sample and while providing collimated illumination of an area within the sample. The microscope includes an objective lens having a fixed position with respect to a second connector for receiving light returning from the sample and focusing it on an image sensor within the microscope that generates an image output, a beamsplitter for separating light returning from the sample, and an electrically-tunable lens positioned between the objective lens and the image sensor for adjusting an optical path length from the optical interface to the image sensor. The illumination is focused at or near a back focal plane of the objective lens to the sample, providing collimated or quasi-collimated illumination on or within the sample.

Abstract: A miniaturized microscope having a tunable focal length provides for fluorescence measurements at an adjustable focus, providing for autofocus and/or depth adjustment of an image measurement without altering or adjusting a probe implanted in a sample and while providing collimated illumination of an area within the sample. The microscope includes an objective lens having a fixed position with respect to a second connector for receiving light returning from the sample and focusing it on an image sensor within the microscope that generates an image output, a beamsplitter for separating light returning from the sample, and an electrically-tunable lens positioned between the objective lens and the image sensor for adjusting an optical path length from the optical interface to the image sensor. The illumination is focused at or near a back focal plane of the objective lens to the sample, providing collimated or quasi-collimated illumination on or within the sample.