An optical system includes a multispectral sensor; an optical filter including a plurality of optical channels that is disposed over the multispectral sensor; and a lens that is disposed over the optical filter. The lens is configured to direct first light that originates from a scene to the optical filter. The optical filter is configured to pass one or more portions of the first light to the multispectral sensor. The multispectral sensor is configured to generate, based on the one or more portions of the first light, spectral data associated with the scene.

In a first aspect of the disclosure there is provided a multi-spectral optical sensor comprising: a monolithic semiconductor chip defining a plurality of subarrays of optical detector regions, each array comprising the same number and relative spatial arrangement of optical detector regions; a plurality of optical filters; and a plurality of lens elements, wherein each optical filter is positioned between a corresponding lens element and a corresponding subarray of optical detector regions such that light from a scene incident on any one of the lens elements along a direction of incidence propagates through the corresponding optical filter towards a corresponding one of the optical detector regions of the corresponding subarray of optical detector regions, which corresponding one of the optical detector regions depending on the direction of incidence, and wherein the incident light forms an out-of-focus image of the scene at a plane of the optical detector regions.

A proximity sensing device includes: a light source, a sensing unit, a light guide unit, and a window. The light source emits light, which is guided by the light guide unit to the window. The emitted light reflected by an object is received by the same window. The light guide unit includes a partial-transmissive-partial-reflective (PTPR) optical element, whereby the light emitted from the light source is reflected by the PTPR optical element, while the light reflected by the object passes through the PTPR optical element. There is only one window required.