A water content sensor for a recording medium includes a single light emitting part, a wavelength separation device and a detector device. The single light emitting part emits infrared light in a wavelength range including an absorption wavelength of water along one incident light path toward the recording medium. The wavelength separation device separates infrared light, either reflected from or transmitted through the recording medium, into a first light in a first wavelength range including the absorption wavelength of water and a second light in a second wavelength range excluding the first wavelength range. The detector device receives the first light in the first wavelength range and the second light in the second wavelength range, and generates a first output corresponding to an intensity of the first light received and a second output corresponding to an intensity of the second light received, respectively.

A water content sensor for a recording medium includes a single light emitting part, a wavelength separation device and a detector device. The single light emitting part emits infrared light in a wavelength range including an absorption wavelength of water along one incident light path toward the recording medium. The wavelength separation device separates infrared light, either reflected from or transmitted through the recording medium, into a first light in a first wavelength range including the absorption wavelength of water and a second light in a second wavelength range excluding the first wavelength range. The detector device receives the first light in the first wavelength range and the second light in the second wavelength range, and generates a first output corresponding to an intensity of the first light received and a second output corresponding to an intensity of the second light received, respectively.

A processing device includes a first light source and a second light source configured to emit light having a peak wavelength from 900 nm to 2,100 nm, a first light receiving portion, a second light receiving portion, and a processing portion configured to subject a medium to processing of increasing or reducing an amount of moisture contained in the medium. the first light source and the first light receiving portion are positioned upstream of the processing portion in a transport direction of the medium, the first light source irradiates, with light, the medium, the first light receiving portion receives light reflected by the medium, the second light source and the second light receiving portion are positioned downstream of the processing portion in the transport direction, the second light source irradiates, with light, the medium, and the second light receiving portion receives light reflected by the medium.

An image forming apparatus includes a feeder, a conveyance section, an image forming section, a light emitter, a light receiver, a measuring section, and a permeation depth calculator. The feeder feeds a sheet. The conveyance section conveys the sheet. The image forming section forms an image on the sheet conveyed by the conveyance section using an ink. The light emitter emits near-infrared light to the sheet with the image thereon. The light receiver receives reflected light of the near-infrared light. The reflected light has been reflected by the sheet with the image thereon. The measuring section measures a received light quantity of the reflected light. The permeation depth calculator calculates a permeation depth of the ink permeating the sheet based on the received light quantity.

A first light emitter emits light toward a sheet. A first light receiver receives first reflected light from the sheet. A second light emitter is arranged downstream of the first light emitter in a conveyance direction of the sheet and emits light toward the sheet. A second light receiver receives second reflected light from the sheet. A measuring section measures first and second received light quantities of the first reflected light and the second reflected light. A moisture content calculator calculates a change in a moisture content of the ink in the sheet based on a difference between first and second moisture contents. The first moisture content is based on the first received light quantity and the second moisture content is based on the second received light quantity. A curling amount calculator calculates a curling amount of the sheet based on the change in the moisture content.

A measurement apparatus of a moving paper web, includes an optical radiation source that outputs optical radiation toward a scattering element of the measurement apparatus. The scattering element scatters the optical radiation, and a transmitting surface of the scattering element directs the optical radiation in a scattered manner toward the moving paper web. A distance between said transmitting surface of the scattering element and a surface of the paper web is known, and the transmitting surface and a detector of the apparatus are on opposite sides of the paper web. The detector receives at least a part of the optical radiation, which is side-scattered from the moving paper web. The detector determines a moisture value and a dry weight of the paper web on the basis of spectral information on the received optical radiation and the known distance.

A measurement apparatus of a moving paper web, includes an optical radiation source that outputs optical radiation toward a scattering element of the measurement apparatus. The scattering element scatters the optical radiation, and a transmitting surface of the scattering element directs the optical radiation in a scattered manner toward the moving paper web. A distance between said transmitting surface of the scattering element and a surface of the paper web is known, and the transmitting surface and a detector of the apparatus are on opposite sides of the paper web. The detector receives at least a part of the optical radiation, which is side-scattered from the moving paper web. The detector determines a moisture value and a dry weight of the paper web on the basis of spectral information on the received optical radiation and the known distance.

An image forming apparatus includes first and second light sources configured to emit light on a recording material, with the light from the second light source having a peak wavelength that is longer than the peak wavelength of the light from the first light source. The apparatus also includes a light receiving unit configured to receive the first light and the second light transmitted through the recording material. A control unit is configured to control an image forming condition on which the image is formed on the recording material based on the first light and the second light received by the light receiving unit. Additionally, a detection device includes first, second, and third light sources configured to emit first light on a sheet. The detection device further includes a light receiving unit configured to receive the first light and the second light transmitted through the sheet and receive the third light reflected on the sheet.

An image forming apparatus includes first and second light sources configured to emit light on a recording material, with the light from the second light source having a peak wavelength that is longer than the peak wavelength of the light from the first light source. The apparatus also includes a light receiving unit configured to receive the first light and the second light transmitted through the recording material. A control unit is configured to control an image forming condition on which the image is formed on the recording material based on the first light and the second light received by the light receiving unit. Additionally, a detection device includes first, second, and third light sources configured to emit first light on a sheet. The detection device further includes a light receiving unit configured to receive the first light and the second light transmitted through the sheet and receive the third light reflected on the sheet.

A web manufacturing supervision system for monitoring properties of a web being transported in a moving direction during a web manufacturing process, includes: a) a radiation source for illuminating a first spot on the web; b) a tunable first detector for capturing signal radiation emanating from the first spot within a signal wavelength band; the signal wavelength band being adjustable to one of at least a first wavelength band and a second wavelength band; c) a second detector for capturing reference radiation emanating from the first spot within a reference wavelength band; d) control means for alternatingly tuning the signal wavelength band to the first wavelength band and the second wavelength band and measuring the signal at both wavelength bands simultaneously.