Optical glass, preform product and optical element

Abstract

PROBLEM TO BE SOLVED: To obtain optical glass having a low partial variance ratio (θg, F) and suppressed in time dependent deterioration of spectral transmittance, while its refractive index (n<SB POS="POST">d< / SB>) and Abbe number (ν<SB POS="POST">d< / SB>) lie within a desired range, and to obtain a preform and an optical element using the same. SOLUTION: The optical glass contains 10.0-40.0 mass% SiO<SB POS="POST">2< / SB>component and 1.0-50.0 mass% Nb<SB POS="POST">2< / SB>O<SB POS="POST">5< / SB>component based on the whole glass mass in a composition in terms of oxide, and has an Abbe number (ν<SB POS="POST">d< / SB>) of ≥15 to ≤30 and the partial variance ratio (θg, F) which satisfies the following relations for the Abbe number (ν<SB POS="POST">d< / SB>): (-0.00160×ν<SB POS="POST">d< / SB>+0.63460)≤(θg, F)≤(-0.00480×ν<SB POS="POST">d< / SB>+0.73500) in the range of ν<SB POS="POST">d< / SB>≤25, and (-0.00250×ν<SB POS="POST">d< / SB>+0.65710)≤(θg, F)≤(-0.00250×ν<SB POS="POST">d< / SB>+0.67750) in the range of ν<SB POS="POST">d< / SB>>25.

Description

technical field [0001] The present invention relates to optical glass, preform and optical element. Background technique [0002] Optical systems such as digital cameras and video cameras, although they vary in size, all contain light bleeding called aberrations. Such aberrations are divided into monochromatic aberration and chromatic aberration, especially chromatic aberration, which strongly depends on the material properties of the lens used in the optical system. [0003] In general, a low-dispersion convex lens and a high-dispersion concave lens are combined to correct chromatic aberration. However, with this combination, only aberrations in the red and green regions can be corrected, and aberrations in the cyan region remain. This aberration in the cyan region that is not completely eliminated is called the secondary spectrum. To correct the secondary spectrum, an optical design that adds the movement of the g-line (435.834nm) in the cyan region is required. At thi...

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Problems solved by technology

[0012] In addition, the glasses disclosed in Patent Documents 1 to 3 have a problem of sun exposure that reduces the spectral transmittance due to ultraviolet rays contained in sunlight or the like.

Glass with strong exposure to sunlight will be colored due to long-term exposure to ultraviolet rays, and it is difficult to maintain the desired spectral transmittance at the time of manufacture.

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