A miniature, micrometer-accuracy, three-dimensional (3D) position-to-optical displacement sensor that has at least one extrinsic Fabry-Perot interferometer (EFPI) in Z direction and a series of plasmonic metasurface resonators with distinctive wavelength-selective characteristics in X and Y directions. The interferometer comprises at least one single mode optic fiber for light propagation, and a substrate mirror to create a light interference fringe as a function of distance between the mirror and the distal end of the optic fiber. Each plasmonic resonator is capable of modifying the substrate mirror and comprises an array of multiple unit nanostructure unit cells that are arranged in a two-dimensional (2D) square lattice or array in the X-Y plane. The nanostructure unit cells are preferably inscribed in the top layer of a three-layer thin film via the focused ion beam (FIB).

In a method for characterizing the surface shape, the following steps are carried out iteratively: (A) calculating a first figure based on first measurements; (B) subtracting the first figure from first measured values, to determine a first test set-up error; (C) using the first test set-up error for calculating a corrected first figure,; (D) subtracting the corrected first figure from second measured values, to determine a second test set-up error; (E) using the second test set-up error for calculating a corrected second figure; (F) using the corrected second figure for correcting the first test set-up error by subtracting the corrected second figure from the first measured values, to determine a corrected first test set-up error; (G) using the corrected first test set-up error for calculating a first figure corrected once again; and (H) comparing the result with a convergence criterion and optionally repeating steps (A) to (H).

A system for optical coherence tomography includes a source of optical radiation, an optical fiber, and a graded index fiber attached to a distal end of the optical fiber. The optical fiber and the graded index fiber are together configured to provide a common path for optical radiation reflected from a reference interface at a distal end of the graded index fiber and from a target.

The invention provides a method for calibration of an optical measurement system, which may be a heterodyne interferometer system, wherein a first optical axis and a second optical axis have a different optical path length, the method comprises: .sup.∘measuring a first measurement value along the first optical axis using a first measurement beam, .sup.∘measuring a second measurement value along the second optical axis using a second measurement beam, .sup.∘changing a wavelength of the first measurement beam and the second measurement beam, .sup.∘measuring a further first measurement value along the first optical axis using the first measurement beam with changed wavelength, measuring a further second measurement value along the second optical axis using the second measurement beam with changed wavelength, .sup.∘determining a cyclic error of the optical measurement system on the basis of the measured values, and .sup.∘storing a corrective value based on the cyclic error.

A distance determining system comprising: a light source, configured to emit light; a first light sensing region, away from the light source for a first distance, comprising at least one first light sensing device; a second light sensing region, away from the light source for a second distance larger than the first distance, comprising at least one second light sensing device; and a processing circuit, configured to compute distance information of an object which reflects the light to the first light sensing region and the second light sensing region, according to a first relation between a first light intensity sensed by the first light sensing region and a second light intensity sensed by the second light sensing region.

Our high phase sensitivity wide-field phase cancellation interferometry system allows single-shot, label-free optical sensing of neural action potentials via imaging of optical path length changes. Single-shot sensing and monitoring of single neurons within a neural network should lead to a more comprehensive understanding neural network processing, which is beneficial for the advancement in the field of neuroscience as well as its biomedical applications and impact. Our system cancels the phase profile of the resting neuron from the phase profile of the spiking neuron, improving the sensitivity by two orders of magnitude. Using a detector with an extremely large well depth and an appropriately biased interferometer increases the sensitivity by another order of magnitude, yielding a measurement that is three orders of magnitude more sensitive than those possible with other microscopes.

Disclosed are a testing apparatus and a testing method. When the testing apparatus is used to test a sample (11) to be tested, a first detection apparatus (21) and a second detection apparatus (22) can be switched by means of an objective lens switching apparatus (20), so as to acquire height information and structure information of the sample (11) to be tested. In the process, the sample (11) to be tested does not need to be transferred between testing apparatuses, thus, not only is pollution potentially created in the process of transferring the sample (11) to be tested avoided, and the probability of the sample (11) to be tested being polluted in the testing process reduced, but also a region to be tested of the sample (11) to be tested does not need to be determined repeatedly, improving the testing speed for the sample (11) to be tested.

An ophthalmic apparatus includes: a light source; a measurement optical system that irradiates an eye with light from the source and guides reflected light from the eye; a reference optical system that guides the light from the source to use the light from the source as reference light; an abnormality detection optical system that has an optical path length of a predetermined length and to guide the light from the source to use the light from the source as abnormality detection light; a light receiving element that receives measurement interference light being combination of the reflected light from the eye and the reference light and abnormality detection interference light being combination of the abnormality detection light and the reference light, and the ophthalmic apparatus determines whether the measurement interference light is abnormal based on waveform of an abnormality detection interference signal outputted from the light receiving element.

A portable communication device includes one or more optical detectors to generate an analog signal in response to a change in an intra-cavity or an emitted optical power of a light source due to light backscattered from a particle and an application-specific integrated circuit (ASIC). The particle is illuminated via a light source. The ASIC includes an analog-to-digital converter (ADC) circuit, a digital delay circuit, a particle detector module and a processor. The ADC converts the analog signal to a digital signal. The digital delay circuit can store the digital signal for a predetermined or dynamically variable time interval. The particle detector module can analyze the digital signal and can generate an enable signal upon detecting a particle signature in the digital signal. The processor is coupled to the digital delay circuit and can start processing the digital signal in response to the enable signal.

Optical pressure sensor assemblies that can be used with existing catheters and imaging systems. Pressure sensors may be compatible with atherectomy and occlusion-crossing catheters, where intravascular pressure measurements at various vessel locations are needed to determine treatment efficacy. The pressure sensors may employ an optical pressure measurement mechanism using optical interferometry, and may be integrated with existing imaging modalities such as OCT. The pressure sensor assemblies may include a movable membrane that deflects in response to intravascular pressure; an optical fiber that transmits light to the movable membrane and receives light reflected or scattered back from the movable membrane into the fiber; and a processor or controller configured to determine the distance traveled by the light received in the fiber from the movable membrane, where the distance traveled is proportional to the intravascular pressure exerted against the membrane.