Conference Agenda

Exploiting nonclassical states of light allows new imaging and sensing approaches. In particular, nonlinear interferometers enable quantum imaging with undetected light. Here, based on the effect of induced coherence, samples can be probed with light that is not detected at all. Instead, its quantum-correlated partner light is recorded and yields the information of the sample, although it never interacted with it. This enables new sensing modalities beyond classical limitations. The talk will outline the fundamental concept, recent progress, limits, and perspectives for biomedical applications of nonlinear interferometers.

We present the Hartmann sensor's capacity, which is traditionally used for wavefront sensing, to measure the coherence properties of the signal. By reinterpreting the detection theory of the conventional Hartmann sensor within the framework of quantum tomography, we unveil the ability to quantify the mutual intensity function in the form of coherence matrix analogue to the density matrix of the mixed quantum state. With this analogy, we can use the quantum-inspired algorithms to reconstruct this matrix from experimental data.

Fast and accurate asphere and freeform measurements are in high demand by the optics manufacturing industry. Interferometric methods such as tilted-wave interferometry meet these demands but require accurate surface positioning of the specimen along the optical axis, since such measurements are sensitive to such positioning errors. In this work the Cat's Eye position will be investigated in terms of accuracy and repeatability as a reference position for surface positioning in tilted-wave interferometry. For this purpose, a two-regime method for specimen alignment using different optimization criteria is investigated and its repeatability is evaluated. Accurate and reproducible positioning into the Cat's Eye position together with interferometric movement tracking will allow accurate specimen positioning along the optical axis, which will significantly reduce the surface measurement errors associated with such misalignment and improve the overall measurement uncertainty.

Shack-Hartmann wavefront sensor is applied today in broad areas of interest. Especially in optical systems quality assessment, the SHWS provides fast and accurate wavefront measurement. The sensitivity, i.e., the minimal measurable change in the wavefront, is usually omitted when it comes to a single Zernike Polynomials level. There is no ISO standard either. Comparing the specifications of SHWS among different manufacturers, one can feel confused. Here, we show the sensitivity for single Zernike polynomials up to the third radial order. In addition, we calculate the minimal wavefront RMS at the quantum limit using Fisher Information theory and compare it with the standard modal reconstruction algorithm used in SHWS.

The analysis carries two regimes: weak signal for adaptive optics and strong signal for optical metrology.

In this presentation, we propose a measurement system to observe 2-D in-plane displacement at a fast sampling rate of 5 kHz using a sinusoidal phase modulation interferometer (SPMI). The SPMI consists of a Michelson interferometer incorporating an electric-optic modulator (EOM) with a modulation frequency of 5 kHz and a high-speed camera (HSC) synchronised to a clock signal at a frequency of 60 kHz, 12 times the modulation frequency. Phase demodulation of each pixel in the camera is performed by acquiring the light intensity signal to that pixel in synchronisation with the sampling signal and performing a specific addition or subtraction of them. By applying this procedure to all pixels in the camera, the 2D in-plane displacement can be obtained. This technique has the potential to measure fast, dynamic deformation of object surfaces and dynamic wavefront aberrations due to air fluctuations.