Multi-pass microscopy

Abstract

Microscopy of biological specimens often requires low light levels to avoid damage. This yields images impaired by shot noise. An improved measurement accuracy at the Heisenberg limit can be achieved exploiting quantum correlations. If sample damage is the limiting resource, an equivalent limit can be reached by passing photons through a specimen multiple times sequentially. Here we use self-imaging cavities and employ a temporal post-selection scheme to present full-field multi-pass polarization and transmission micrographs with variance reductions of 4.4±0.8 dB (11.6±0.8 dB in a lossless setup) and 4.8±0.8 dB, respectively, compared with the single-pass shot-noise limit. If the accuracy is limited by the number of detected probe particles, our measurements show a variance reduction of 25.9±0.9 dB. The contrast enhancement capabilities in imaging and in diffraction studies are demonstrated with nanostructured samples and with embryonic kidney 293T cells. This approach to Heisenberg-limited microscopy does not rely on quantum state engineering.

Full-field cavity enhanced microscopy techniques

“…It will further be restricted to scalar fields. In comparison to the treatment in [4], we do not neglect reflected fields and we allow for arbitrary samples that affect both the amplitude and the phase of the incoming field.…”

“…Cavity enhanced measurements are ubiquitous in science and technology. In microscopy, the offered sensitivity enhancement has for example been exploited in cavity scanning microscopy [1,2], in Tolansky interferometry [3] and in multi-pass (MP) microscopy [4,5]. While the former represents a point scanning technique, in which a fiber based microcavity is scanned across a sample, the latter two offer a full field of view.…”

“…This reduces the achievable transverse resolution to a few wavelengths of the probe light [6]. This can be avoided if the sample is placed in a self-imaging cavity [7,8], as done in MP microscopy [4], a geometry that allows for 2D imaging and that is applicable to a wider range of samples, as long as photon loss is small.…”

“…The detection can either be done in a time-resolved way, in which the number of interactions is recorded for each detected photon, or in a time-integrating way. The MP scheme [4], in which a pulse of light is incoupled into the self-imaging cavity and interacts with the specimen exactly m times before it is outcoupled and detected.…”

Multiphoton Interference in Quantum Fourier Transform Circuits and Applications to Quantum Metrology

“…Unfortunately, the high sensitivity is due to the linearly increasing phase shift {(j − 1)ϕ} n j=1 , but not the quantum nature of multiphoton interference [22]. Nevertheless, the linear scheme is superresolving and could have applications to quantum microscopy [23]. Note that the largest relative phase shift is (n − 1)ϕ ∼ nϕ.…”