An inspection apparatus includes a light emitting unit, a first lens, an aperture unit, a second lens, a light receiving unit, and an inspection unit. The light emitting unit emits irradiation light to an object to be inspected. The first lens changes a divergence level of the irradiation light which is emitted from the light emitting unit and is transmitted through the first lens. The aperture unit has an opening which narrows the irradiation light transmitted through the first lens. The second lens condenses the irradiation light passing through the opening, toward the object. The light receiving unit is disposed between the aperture unit and the second lens. The light receiving unit includes plural light receiving elements which receives reflected light obtained by the irradiation light being emitted to the object and then being transmitted through the second lens.

A problem to be solved is to make plural Ge PDs uniform in sensitivity by heating based on the Ge PDs with heaters photocurrent measurements taken by a current monitor, and thereby curb deterioration in a common-mode rejection ratio. A photodetector according to the present invention is a germanium photodetector (Ge PD) that uses germanium or a germanium compound in a light absorption layer, the photodetector including two or more Ge PDs placed to receive an input differential signal; a current monitor adapted to measure photocurrents of the two or more Ge PDs; resistors adapted to heat the respective Ge PDs; voltage sources connected to the respective resistors and capable of controlling voltage values independently of each other, wherein the voltage sources are connected with the current monitor, and the voltage sources manipulate voltages applied to the heaters such that current values output by the two or more Ge PDs will match each other.

A system for compensating for photodiode errors includes a live photodiode configured to be exposed to a light source and to output a live signal. The system further includes a reference photodiode located proximate to the live photodiode and configured to be isolated from the light source and to output a reference signal. The system further includes a controller configured to generate a compensated output signal by subtracting the reference signal from the live signal.

Provided are an optical receiver that can realize a reduction in the variation of sensitivity in the ultraviolet light region and a reduction in noise in the visible light region and the infrared light region, a portable electronic device, and a method of producing an optical receiver. The first light-receiving device (PD1) and the second light-receiving device (PD2) of the optical receiver (1) are each constituted by forming a second conductivity-type N-type well layer (N_well) on a first conductivity-type P-type substrate (P_sub), forming a first conductivity-type P-type well layer (P_well) in the N-type well layer (N_well), and forming a second conductivity-type N-type diffusion layer (N) in the P-type well layer (P_well). The P-type substrate P_sub, the N-type well layer (N_well), and the P-type well layer (P_well) are electrically at the same potential or are short-circuited.

An embodiment of a method for compensating variations in an attenuation of light of an optical filter of a light sensor system comprises illuminating a clear sensor and a color sensor of the light sensor system with a test light having a test spectrum. Therein the color sensor comprises the optical filter and is designed to predominantly sense light with a wavelength within a pass band of the filter; and the test spectrum has components outside the pass band. A clear test signal generated by the clear sensor and a color test signal generated by the color sensor are received in particular in response to the illumination with the test light. Then a first transmission value T is determined based on the clear test signal and on the color test signal. Finally, a compensation factor Kr, Kg, Kb is calculated to compensate the variations in the attenuation of light based on the first transmission value T and a nominal transmission value Tn of the filter.

Disclosed are optical devices and methods of manufacturing optical devices. An optical device can include a substrate; an optical emitter chip affixed to the front surface of the substrate; and an optical sensor chip affixed to the front surface of the substrate. The optical sensor chip can include a main sensor and a reference sensor. The optical device can include an opaque dam separating the main optical sensor and the reference sensor. The optical device can include a first transparent encapsulation block encapsulating the optical emitter chip and the reference optical sensor and a second transparent encapsulation block encapsulating the main optical sensor. The optical device can include an opaque encapsulation material encapsulating the first transparent encapsulation block and the second transparent encapsulation block with a first opening above the main optical sensor and a second opening above the optical emitter chip.

A diamond identification apparatus is disclosed, the diamond identification apparatus comprising a support platform for receiving a gemstone at an observation position, a first light source arranged to emit light at a predetermined angle towards the observation position and a first photodiode arranged to detect an amount of light from the first light source being reflected from the gemstone at the observation position. The diamond identification apparatus further comprises a second light source arranged to emit light towards the observation position, a second photodiode arranged to detect light from the second light source that passes through the gemstone at the observation position and a processor unit.

An integrated quantum random noise source includes a substrate, an optical oscillator that may be integral to the substrate coupled by an optical waveguide to an optical directional coupler. The optical directional coupler has two outputs that are coupled by optical waveguides to a pair of photodetectors that are part of a balanced photodetector. The balanced photodetector in response outputs an analogue signal proportional to the difference in photocurrents of the two photodetectors. The analogue output signal from the balanced photodetector is a random Gaussian-distributed signal representative of quadrature measurements on the quantum vacuum state of light. The random noise source can be coupled other apparatus to provide a source of random bits.

A detector has a sensor responsive to a first wavelength, a sensor responsive to a second wavelength, and a sensor for collecting reference readings. A gas sample is analysed to obtain readings corresponding to the first wavelength, the second wavelength and a reference. A first absorption figure is calculated using the first reading and the reference reading, and a second absorption figure using the second reading and the reference reading. A lineariser function is applied to the first and second absorption figures to calculate first and second concentration figures. The sensor for each wavelength is calibrated for detecting the first gas such that the data collected at each wavelength gives the same reading when only the first gas is present. The ratio of the first concentration figure to the second concentration figure is used to identify whether only the first gas is present.

Provided are gaze tracking apparatuses, which in some embodiments can include an optoelectronic device, wherein the optoelectronic device includes an image sensor with non-local readout circuit having a substrate and a plurality of pixels and operatively connected to a control unit, wherein a first area of the substrate is at least partially transparent to visible light and at least the plurality of pixels of the image sensor are arranged on the first area of the substrate to aim to an eye of a user when placed in front of an inner face of the substrate, and wherein the control unit is also adapted to control the image sensor to acquire image information from the user's eye for performing a gaze tracking of the user's eye.