| 摘要 |
An objective lens system is provided and includes a spherical sapphire lens element, an aspheric first polymeric material lens element, and an aspheric second polymeric material lens element, all of which are axially aligned. The sapphire lens element is coupled to the first polymeric material lens element to form a meniscus shaped air lens element. When inserted as a component of an endoscope, the planar surface of the sapphire lens forms a robust outer distal window at the distal end of the endoscope and the flat surface of the second polymeric material lens element is attached to the relay lens system of the endoscope. The initial image of the observed area formed at the proximal end of the objective lens system is "buried" in a higher index medium than air thus allowing for easier coupling to a relay lens system leading to lower overall f/numbers. The dissimilar indices and dispersion qualities of the elements of the objective lens design and air gaps therebetween provide an improved correcting means for chromatic and geometric aberrations, and thus a higher overall quality optical image. Embodiments disclosed allow for direct coupling to a monolithic plastic relay lens.
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