Olympus Optical Company, Ltd.

Olympus Corporation

Yuko Morita

Hiroaki Kinoshita

Takayoshi Togino

Satoshi Noda

Hisashi Koike

A lightweight and homogeneous optical element exhibiting favorably weak birefringence and hygroscopicity as well as superior productivity and producing minimal chromatic aberrations is formed by using an organic-inorganic composite material having both the properties of a glass material and those of a plastic material. The optical element has at least one entrance refracting surface and at least one exit refracting surface. The optical element is formed from an organic-inorganic composite material having an inorganic phase dispersed in the three-dimensional network (matrix) of an organic phase.

Optical element using organic-inorganic composite material

A porous body,and a first immersing solution,are put in a vessel,in proportions such that the whole of the porous body,is immersed in the immersing solution, and the immersing is conducted for an arbitrary period of time. The vessel,is formed so as to have a depth greater than the height of the porous body,A vessel-capacity changing device,is inserted in the vessel,The first immersing solution,overflows from the interstice between the vessel-capacity changing device,and the vessel,A second immersing solution,is poured through a charging port, and simultaneously the vessel-capacity changing device,is lifted to thereby remove the same from the immersing solution. Thus, the porous body,is immersed in the second immersing solution,without being exposed to the outside air to thereby complete solution replacement. The immersing of the porous body can be effected safely, securely and at a lowered cost without damaging the porous body.

Method of solution doping a sol gel body via immersion

A gradient-index optical element comprises SiO,, BaO, and TiO,as essential components, and has a refractive index profile in its diametrical direction. The molar ratio of barium to silicon at the center of the element in its diametrical direction is limited to Ba/Si&gE;0.4. This gradient-index optical element has a small refractive index difference with reduced chromatic aberrations and, hence, is suitable for use with optical equipment.

Gradient-index optical element and its fabrication method

The invention provides a process for making a gradient index optical element having a precisely parabolic configuration of refractive index profile. After a concentration profile is imparted across a gel prepared by a sol-gel technique, the concentration profile is fixed. In this case, the treatment with a concentration profile-fixing solution is carried out at a temperature higher than that at which the treatment with a concentration profile-imparting solution is carried out, whereby the rate of fixing the concentration profile is so higher than that of imparting the concentration profile, so that any possible deformation of the concentration profile formed at the concentration profile-imparting step is reduced or inhibited.

Process for making gradient index optical elements

At least one metal species g is selected from the metal group G consisting of Nb, Ta, Pb, Ti, Tl and Zr. At least one metal species f is selected from the metal group F1 consisting of La, In, Y, Zr and Ta. The metal species g and f are not simultaneously Ta or Zr. The metal species g and f have concentrations distributed in mutually reverse directions. The element exhibits a ratio of dCf/dCg, in which dCf and dCg represent concentration distribution gradients of metal species f and g, respectively, ranging from -4 to -0.2. Alternatively, at least one metal species f may be selected from the metal group F2 consisting of Ga, Sn, Ba, Sr and Ca, while causing the ratio of dCf/dCg to be in the range of from -7 to -0.5. Thus, a gradient index optical element is obtained, which exhibits less refractive index change and large Abbe number change and is hence superior to conventional elements in correction of chromatic aberration.

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Hachiohji, Japan

Yuko Morita