An optical measurement instrument includes optical coherence tomography (OCT) interferometer and a pupil retro illumination system which directs laser light onto the retina of an eye via the sample arm of the OCT interferometer. The laser light passes through an intraocular lens (IOL) implanted into the eye, and an iris camera captures an image of the eye from a portion of the light returned from the retina of the eye, the returned light also passing through the IOL. One or more fiducials of the IOL are detected from the captured image, and an angular orientation of the eye is ascertained from the one or more detected fiducials.

Aspects of the subject technology relate to particulate matter sensors for electronic devices. A particulate matter sensor may include three lasers, three total-internal-reflection lenses, and three detectors for detecting changes in the operation of the three lasers due to the principles of self-mixing interferometry. The three total-internal-reflection lenses may use internally reflective surfaces to tilt the three beams into three corresponding directions that form an orthogonal basis in the three dimensional space, so that a gas flow speed can be determined while maintaining a small, modular form factor for implementation of the sensor in portable electronic devices.

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.

An ophthalmic apparatus that includes a light source of wavelength sweeping type; a measurement optical system; a reference optical system; a light receiving element that receives interference light; a sample clock signal generator that generates a sample clock signal from the light from the light source, the sample clock signal cyclically changing at equal frequency intervals; a signal processor that samples an interference signal based on the sample clock signal, the interference signal being outputted from the light receiving element when the light receiving element receives the interference light. The ophthalmic apparatus generates period data based on the sample clock signal, the period data indicating a relationship between a period of the sample clock signal and time; and determines a processing duration of the interference signal sampled at the signal processor based on the period data.

An optical interferometer includes a branching-combining unit, a first optical system, a second optical system, and a drive unit. The branching-combining unit includes a branching surface, an incident surface, a first output surface, a combining surface, and a second output surface on an interface of a transparent member, the branching surface partially reflects incident light and outputs as first branched light, and transmits the rest of the incident light into the interior as second branched light, the combining surface partially combines the first branched light and the second branched light to be output to the outside as first combined light, and combines the rest of the first branched light and the second branched light to be propagated into the interior as second combined light, and the second output surface partially outputs the second combined light to the outside.

Inspecting a multilayer sample. In one example embodiment, a method may receiving, at a beam splitter, light and splitting the light into first and second portions; combining, at the beam splitter, the first portion of the light after being reflected from a multilayer sample and the second portion of the light after being reflected from a reflector; receiving, at a computer-controlled system for analyzing Fabry-Perot fringes, the combined light and spectrally analyzing the combined light to determine a value of a total power impinging a slit of the system for analyzing Fabry-Perot fringes; determining an optical path difference (OPD); recording an interferogram that plots the value versus the OPD for the OPD; performing the previous acts of the method one or more additional times with a different OPD; and using the interferogram for each of the different OPDs to determine the thicknesses and order of the layers of the multilayer sample.

An optical measuring system for a measuring machine includes at least two scanning devices for intermittently moving through alternately timed sequences of static measuring positions at which a measuring beam is directed to and from a test object. An optical switch selectively routes the measuring beam through any one of the scanning devices that has settled into one of the static measuring positions.

Aspects of the subject technology relate to particulate matter sensors for electronic devices. A particulate matter sensor may include three lasers, three total-internal-reflection lenses, and three detectors for detecting changes in the operation of the three lasers due to the principles of self-mixing interferometry. The three total-internal-reflection lenses may use internally reflective surfaces to tilt the three beams into three corresponding directions that form an orthogonal basis in the three dimensional space, so that a gas flow speed can be determined while maintaining a small, modular form factor for implementation of the sensor in portable electronic devices.

Various systems and methods for sequential angle illumination to achieve ultra-high resolution optical coherence tomography (OCT) images. One example OCT system includes a light source, a beam divider, sample arm optics, a detector, and a processor. The light source generates a light beam to illuminate the sample. The beam divider separates the light beam into reference and sample arms. The sample arm optics sequentially illuminates a location in the sample with the light beam from different angles. The detector receives light returned from the reference arm and the sample illuminated at each angle and generates signals. The processor combines the signals to generate an image, which has a transverse resolution that is higher than the transverse resolution achieved from the signal generated from a single angle.

A wafer shape metrology system includes a wafer shape metrology sub-system configured to perform one or more stress-free shape measurements on a first wafer, a second wafer, and a post-bonding pair of the first and second wafers. The wafer shape metrology system includes a controller communicatively coupled to the wafer shape metrology sub-system. The controller is configured to receive stress-free shape measurements from the wafer shape sub-system; predict overlay between one or more features on the first wafer and the second wafer based on the stress-free shape measurements of the first wafer, the second wafer, and the post-bonding pair of the first wafer and the second wafer; and provide a feedback adjustment to one or more process tools based on the predicted overlay. Additionally, feedforward and feedback adjustments may be provided to one or more process tools.