Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for generating a content item recommendation. For example, a system can receive a request for a content item recommendation for a particular user; obtain data specifying, for each of a set of one or more content items that have been interacted with by the particular user, a respective cluster of content items to which the content item belongs; select, using the respective clusters for the content items in the set, a next cluster of content items from a plurality of clusters to recommend to the particular user; and select, as content items to recommend to the particular user, one or more content items from the next cluster.

Abstract: A non-paraxial Talbot spectrometer includes a transmission grating to receive incident light. The grating period of the transmission grating is comparable to the wavelength of interest so as to allow the Talbot spectrometer to operate outside the paraxial limit. Light transmitted through the transmission grating forms periodic Talbot images. A tilted detector is employed to simultaneously sample the Talbot images at various distances along a direction perpendicular to the grating. Spectral information of the incident light can be calculated by taking Fourier transform of the measured Talbot images or by comparing the measured Talbot images with a library of intensity patterns acquired with light sources having known wavelengths.

Abstract: A non-paraxial Talbot spectrometer includes a transmission grating to receive incident light. The grating period of the transmission grating is comparable to the wavelength of interest so as to allow the Talbot spectrometer to operate outside the paraxial limit. Light transmitted through the transmission grating forms periodic Talbot images. A tilted detector is employed to simultaneously sample the Talbot images at various distances along a direction perpendicular to the grating. Spectral information of the incident light can be calculated by taking Fourier transform of the measured Talbot images or by comparing the measured Talbot images with a library of intensity patterns acquired with light sources having known wavelengths.

Abstract: A non-paraxial Talbot spectrometer includes a transmission grating to receive incident light. The grating period of the transmission grating is comparable to the wavelength of interest so as to allow the Talbot spectrometer to operate outside the paraxial limit. Light transmitted through the transmission grating forms periodic Talbot images. A tilted detector is employed to simultaneously sample the Talbot images at various distances along a direction perpendicular to the grating. Spectral information of the incident light can be calculated by taking Fourier transform of the measured Talbot images or by comparing the measured Talbot images with a library of intensity patterns acquired with light sources having known wavelengths.

Abstract: A non-paraxial Talbot spectrometer includes a transmission grating to receive incident light. The grating period of the transmission grating is comparable to the wavelength of interest so as to allow the Talbot spectrometer to operate outside the paraxial limit. Light transmitted through the transmission grating forms periodic Talbot images. A tilted detector is employed to simultaneously sample the Talbot images at various distances along a direction perpendicular to the grating. Spectral information of the incident light can be calculated by taking Fourier transform of the measured Talbot images or by comparing the measured Talbot images with a library of intensity patterns acquired with light sources having known wavelengths.

Abstract: A non-paraxial Talbot spectrometer includes a transmission grating to receive incident light. The grating period of the transmission grating is comparable to the wavelength of interest so as to allow the Talbot spectrometer to operate outside the paraxial limit. Light transmitted through the transmission grating forms periodic Talbot images. A tilted detector is employed to simultaneously sample the Talbot images at various distances along a direction perpendicular to the grating. Spectral information of the incident light can be calculated by taking Fourier transform of the measured Talbot images or by comparing the measured Talbot images with a library of intensity patterns acquired with light sources having known wavelengths.

Abstract: A non-paraxial Talbot spectrometer includes a transmission grating to receive incident light. The grating period of the transmission grating is comparable to the wavelength of interest so as to allow the Talbot spectrometer to operate outside the paraxial limit. Light transmitted through the transmission grating forms periodic Talbot images. A tilted detector is employed to simultaneously sample the Talbot images at various distances along a direction perpendicular to the grating. Spectral information of the incident light can be calculated by taking Fourier transform of the measured Talbot images or by comparing the measured Talbot images with a library of intensity patterns acquired with light sources having known wavelengths.