Multi-spectral imaging

Abstract

A multi-spectral camera comprises a blocking element (201) having at least one hole (203) allowing light to pass through. A dispersive element (205) spreads light from the at least one hole (203) in different wavelength dependent directions and a lens (207) focuses light from the dispersive element (205) on an image plane (209). A microlens array (211) receives light from the lens (207) and an image sensor (213) receives the light from the microlens array (211) and generates a pixel value signal which comprises incident light values for the pixels of the image sensor (213). A processor then generates a multi-spectral image from the pixel value signal. The approach may allow a single instantaneous sensor measurement to provide a multi-spectral image comprising at least one spatial dimension and one spectral dimension. The multi-spectral image may be generated by post-processing of the sensor output and no physical filtering or moving parts are necessary.

Description

technical field [0001] The present invention relates to multispectral imaging, and in particular but not exclusively to generating multispectral images comprising two spatial and one spectral dimensions. Background technique [0002] The human eye is characterized by three types of cones sensitive to different parts of the visible spectrum. These cones are usually labeled L, M, and S referring to the wavelengths they sense (long, medium, and short, which roughly correspond to red, green, and blue). exist figure 1 The relative spectral sensitivity of the cones is shown in , which shows that the cones have a rather broadband character and correspond to the integration of light over a broad wavelength range. Thus, it is possible to have two materials with different spectral characteristics appear to a human observer to have the same color under certain light conditions. This phenomenon is called metamerism. Similar to the human eye, a three-primary-color (RGB) system using ...

AI Technical Summary

Problems solved by technology

A major drawback of this approach is that the light efficiency appears to be rather low since much of the light is blocked by the filter

Also, appropriate filters such as Liquid Crystal Tunable Filters and Acousto-Optical Tunable Filters are quite expensive and usually only allow a single wavelength of light to pass through (trap)

Said methods also tend to have the same disadvantages as scanning multispectral cameras, namely slowness, relatively low reliability, etc.

[0015] A particularly important disadvantage of these types of multispectral cameras is that they sacrifice spectral resolution for temporal resolution

This is disadvantageous in situations where the object being imaged is moving

Furthermore, the methods generally have a very specific (fixed) spectral resolution, which cannot be easily adapted to the application

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