Patent ID: 11048097

Abstract:
The invention relates to an optical filter (1) for transmitting light (13) of a pass wavelength (17), comprising at least two optical filter stages (3) arranged along a transmission direction (11), along which the light (13) of the pass wavelength (17) is transmitted through the optical filter (1), wherein each of the at least two optical filter stages (3) comprises at least one entrance polarizing element (5) and at least one constant retarding element (7). The invention further relates to a camera (53) for simultaneously capturing at least two images, wherein each image is limited to light (13) in a limited spectral band (44) and to a multi-spectral imaging system (87) and an illumination system (73) applying the inventive optical filter (1). Solutions of the art have low peak transmission values and may furthermore only provide monochrome images in real time. The present invention improves optical filters (1) of the art by each of the at least two optical filter stages (3) comprising a periodic transmission characteristic (35) that extends over a working wavelength range (41), wherein each transmission characteristic (35) comprises at least two peaks (43c-43e), which each overlap at least one peak (43c-43d) of each of the other transmission characteristics (35) and wherein an overall transmission characteristic (29) of the optical filter (1) comprises at least two spectral passbands (45) that are spectrally separated from each other. The inventive camera (53), multi-spectral imaging system (87) and inventive illumination system (73) apply an optical filter (1) according to the invention.