| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an observation optical system which has a long working distance (WD) or is a non-contact type. <P>SOLUTION: The optical device is provided with an optical source 303, an optical element (negative refractive index medium 301) formed with a medium showing negative refractivity and a correction means (optical source driving device 350) which corrects fluctuations of refractive index of the optical element by changing a wavelength of used light in order to correct fluctuations of imaging performance caused by fluctuations of refractive index of the optical element or air. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
