Optical filter and tunable filter

A optical filter comprising:

• a first dispersive element for dispersing an incident light for each wavelength of the light to emit the dispersed light;
• a focusing element for focusing lights of wavelengths dispersed for each wavelength by said first dispersive element on an identical plane with keeping a relative relationship of incident position;
• a patterning plate which is provided at a position where belt-shaped lights from said focusing element are focused on and which transmits lights of predetermined wavelengths at predetermined transmittance;
• a light collection element for collecting lights of respective wavelength which transmitted said patterning plate;
• and
• a second dispersive element for multiplexing dispersed lights collected by said light collection element.

An optical filter comprising:

• a dispersive element for dispersing an incident light for each wavelength of the light to emit the dispersed light and for multiplexing selected reflected lights again toward an opposite direction of said incident light;
• a focusing element for focusing lights of wavelengths dispersed for each wavelength by said dispersive element on an identical plane with keeping a relative relationship of incident position;
• a patterning plate which is provided at a position where belt-shaped lights from said focusing element are focused on and which reflects lights of predetermined wavelengths at predetermined reflectance;
• and
• a driver for driving said patterning plate to be moved or to be rotated.

A optical filter comprising:

• a first dispersive element for dispersing an incident light for each wavelength of the light to emit the dispersed light;
• a focusing element for focusing lights of wavelengths dispersed for each wavelength by said first dispersive element on an identical plane with keeping a relative relationship of incident position;
• a patterning plate which is provided at a position where belt-shaped lights from said focusing element are focused on and which transmits lights of predetermined wavelengths at predetermined transmittance;
• a light collection element for collecting lights of respective wavelength which transmitted said patterning plate;
• a second dispersive element for multiplexing dispersed lights collected by said light collection element;
• and
• a driver for driving said patterning plate to be moved or to be rotated.