Optical system with wavelength selecting device

Abstract

The object is to provide an optical system with a wavelength selecting device. According to one aspect of the present invention, an optical system with a wavelength selecting device includes, in order from an object along an optical axis, an objective optical system composed of optical elements having refractive power and an aperture stop, a no-power optical group composed of optical elements having no refractive power, and an imaging device. The no-power optical group includes the wavelength selecting device for making short wavelength light be selectively substantially non-transparent. The wavelength selecting device preferably satisfies the predetermined conditional expressions.

1 . An optical system with a wavelength selecting device comprising, in order from an object along an optical axis: 
 an objective optical system composed of optical elements having refractive power and an aperture stop;    a no-power optical group composed of optical elements having no refractive power; and    an imaging device;    the no-power optical group including the wavelength selecting device for making short wavelength light be selectively substantially non-transparent; and    the following conditional expression being satisfied by the wavelength selecting device:      390<λ V50 <430    where λ V50  denotes the wavelength (unit: nm) of short wavelength light whose transmittance of the wavelength selecting device is 50%.    
   
   
       2 . The optical system with a wavelength selecting device according to  claim 1 , 
 wherein the wavelength selecting device is an absorption filter which absorbs short wavelength light and is, with respect to the short wavelength light, selectively substantially non-transparent; and wherein the following conditional expression is satisfied:      10<λ V80 −λ V10 <40    where λ V10  denotes the wavelength (unit: nm) of short wavelength whose transmittance of the wavelength selecting device is 10%, and λ V80  denotes the wavelength (unit: nm) of short wavelength light whose transmittance of the wavelength selecting device is 80%.    
   
   
       3 - 16 . (cancelled)  
   
   
       17 . An optical system with a wavelength selecting device comprising, in order from an object along the optical axis: 
 an objective optical system composed of an optical element having refractive power and an aperture stop;    a no-power optical group composed of optical elements having no refractive power; and    an imaging device;    the no-power optical group including a wavelength selecting device which is, with respect to short wavelength light, selectively substantially non-transparent; and    the wavelength selecting device being an interference filter which is, with respect to the short wavelength light, selectively substantially non-transparent by the interference film formed on the surface only of the no-power optical group.    
   
   
       18 . The optical system with a wavelength selecting device according to  claim 17 , wherein the most image side optical element has positive refractive power.  
   
   
       19 - 54 . (cancelled)