| 摘要 |
PURPOSE:To obtain fine image forming characteristics by applying a magnetic field to a projection lens and generating Farady effect at least in a part of lenses constituting the projection lens to change its rfractive index and to control the intensity or direction of the magnetic field. CONSTITUTION:The lens barrel of the projection lens L consists of a diamagnet ic material or a paramagnetic material and a magnetic field H due to a coil C is also formed on a glass part in the lens L. When monochromatic straight polarized light is advanced in the direction of the magnetic field having intensity H(A/m), the plane of the polarization is rotated by theta(rad) in each length l(m) on the basis of the Farady effect and expressed as theta=VlH by using a Verdet's constant V. The constant V is expressed as V=(theta/CH)DELTAne by using the angular frequency omega of light, an optical speed C is a vacuum and the change DELTAne of the refractive index of reverse inner polarization at the absence of the magnetic field, and when omega=2pi/lambda (lambda is the wavelength of light), V=(2pi/lambdaH)DELTAne is formed. Thereby, DELTAne=(lambda/2pi)VH is formed and the change of the refractive index is proportional to the intensity H of the magnetic field. Thus, the intensity and direction of the magnetic field can be controlled by changing the refractive index.
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