US Patent 10048573 Projector system and imaging device

In an imaging section (imaging device), optical filters constituting an optical filter device are inserted and extracted, and an aperture varies an f-number in accordance with the insertion and the extraction of the optical filters. Thus, during the writing operation to the surface of the projection screen, namely during the interactive projector operation, entering of the light in the wavelength band other than that of the detected light DL is suppressed while capturing the detected light DL with the necessary light intensity, and during an alignment (a calibration), the axial chromatic aberration caused by the difference in wavelength band between the pattern image light GL as the image light and the detected light DL is suppressed to achieve an improvement in accuracy.