The optical sensor of the present disclosure includes: a light source configured to emit irradiation light to a target; a light receiver configured to receive a first incident light, a second incident light, and a third incident light travelling from the target and having different wavelength bands; and a controller configured to control the light source. The light receiver includes: a first light-receiving element configured to receive the first incident light and the second incident light and not to receive the third incident light; and a second light-receiving element configured to receive the third incident light and to receive neither the first incident light nor the second incident light.

Measurement apparatus including an optical sensor, which performs repeatedly transmission measurements through moving sheet of paper or board at at least one wavelength band dominantly absorbed by water, at at least one wavelength band dominantly absorbed by cellulose. The apparatus also includes an X-ray sensor, which performs repeatedly transmission measurements through the moving sheet of paper or board with photons of electromagnetic radiation (1 keV to 10 keV). The apparatus comprises a data processing unit, which receives signals with information on intensities of the optical and X-ray radiations passed through the sheet from the optical sensor and the X-ray sensor, and determines, based on the information, all of the following of the moving sheet: the dry stuff content as a function of the cellulose mass per unit area of the sheet, water mass per unit area of the sheet and the ash mass per unit area of the sheet.

A measurement device includes: a first measurement unit, disposed at a first opposing position facing a portion of a sheet-like measurement target, that measures a first physical property of the measurement target by causing the measurement target to vibrate with an ultrasonic wave; a second measurement unit, disposed at a second opposing position facing another portion of the measurement target in a state in which the first measurement unit is facing the first portion, that pinches and restrains the other portion in a thickness direction and measures a second physical property other than the first physical property of the measurement target; and a disposed unit disposed between the first measurement unit and the second measurement unit in an intersecting direction with respect to the thickness direction of the measurement target.

A recording medium determination device includes a light emitter, a light detector, and a hardware processor. The light emitter emits inspection light to a recording medium. The light detector detects incident light including at least one of diffuse reflected light of the inspection light emitted to the recording medium and fluorescent light excited by the inspection light in the recording medium. The hardware processor makes a determination depending on a property of the recording medium based on a detection result of first incident light of the incident light in accordance with first inspection light of the inspection light and second incident light of the incident light in accordance with second inspection light of the inspection light obtained by the light detector. The second inspection light has an intensity whose peak wavelength is shorter than the peak wavelength of the first inspection light.

A flexural-rigidity measuring apparatus includes an ultrasonic device including an oscillating unit that oscillates an ultrasonic wave toward a sheet and a receiving unit that receives the ultrasonic wave that has passed through the sheet, an electromagnetic induction device including an electromagnetic induction unit that generates electromagnetic induction with respect to a sheet, and a near-infrared spectroscopic device including a light-emitting unit that emits near-infrared light toward a sheet and a light-receiving unit that receives the near-infrared light that has passed through the sheet.

An image forming apparatus includes a detection sensor to irradiate light to a recording medium passing through a printing path, and detect an amount of light, a driving device to move a cleaning member to a cleaning region overlapping the printing path to clean a light window of the detection sensor, and a processor to confirm a position of the cleaning member based on the amount of light detected by the detection sensor and control the driving device to move the cleaning member based on the confirmed position.

An aim is to reduce the size of an optical sensor which detects radiated light such as phosphorescence radiated from a detection target excited by exciting light, and to increase a radiated light receiving surface of the optical sensor. An optical sensor is configured to be provided with: a light source which irradiates excitation light; a light detector which detects radiation light emitted from a detection target excited by the excitation light; and a single light guide unit which guides the excitation light to the detection target and guides the radiation light to the light detector.

Measurement apparatus including an optical sensor, which performs repeatedly transmission measurements through moving sheet of paper or board at at least one wavelength band dominantly absorbed by water, at at least one wavelength band dominantly absorbed by cellulose. The apparatus also includes an X-ray sensor, which performs repeatedly transmission measurements through the moving sheet of paper or board with photons of electromagnetic radiation (1 keV to 10 keV). The apparatus comprises a data processing unit, which receives signals with information on intensities of the optical and X-ray radiations passed through the sheet from the optical sensor and the X-ray sensor, and determines, based on the information, all of the following of the moving sheet: the dry stuff content as a function of the cellulose mass per unit area of the sheet, water mass per unit area of the sheet and the ash mass per unit area of the sheet.

Provided is a method for the simultaneous determination of parameters, in particular of at least two, three or four parameters, of at least one resin layer applied to at least one carrier material by recording and evaluating at least one NIR spectrum in a wavelength range between 500 nm and 2500 nm, preferably between 700 nm and 2000 nm, more preferably between 900 nm and 1700 nm, and particularly advantageously between 1450 nm and 1550 nm, using at least one NIR measuring head, in particular at least one NIR multimeter head.

Reflective or embossed regions are supposed to be illuminated as uniformly as possible over the greatest possible angle range for optical inspection using in one aspect an apparatus for inspection having a passive lighting body spotlighted by a spotlight light source, which body illuminates a test region, as well as at least one optical sensor directed at the test region. The lighting body is configured to be partially transmissible, and the optical sensor is disposed, with reference to the test region, optically beyond the lighting body, detecting the test region through the lighting body, and/or the spotlight light source is directed at the lighting body and the lighting body extends continuously over at least 120° in a section plane that stands perpendicular to the surface of the flat items to be tested or inspected.