1. A mother glass rod for a gradient index rod lens having a coreclad structure,
wherein a clad glass composition that forms a clad is a clad glass composition that comprises the following components, indicated by mol %:
45 to 65% SiO2;
0.5 to 10% TiO2;
0 to 15% B2O3;
0 to 7% Al2O3;
0.1 to 10% Bi2O3;
0 to 5% Li2O;
5 to 30% Na2O;
0 to 10% K2O;
0 to 15% MgO;
0 to 10% CaO;
0 to 10% SrO;
0.5 to 10% BaO;
0 to 10% Cs2O;
0 to 10% ZnO;
0 to 7% Y2O3;
0 to 7% Nb2O5;
0 to 7% In2O3;
0 to 7% La2O3;
0 to 10% Ta2O5;
0 to 7% ZrO2; and
0 to 1% Sb2O3,
where the total of Li2O+Na2O+K2O is in a range of 5 to 35 mol %,
the total of MgO+CaO+SrO+BaO is in a range of 2 to 20 mol %,
the total of Li2O+Na2O+K2O+MgO+CaO+SrO+BaO is in a range of 7 to 50 mol %, and
the total of Cs2O+ZnO+Y2O3+Nb2O5+In2O3+La2O3+ZrO2+Ta2O5 is in a range of 0 to 15 mol %,
at least two molar ratios selected from the group consisting of:
MgO(MgO+CaO+SrO+BaO);
CaO(MgO+CaO+SrO+BaO);
SrO(MgO+CaO+SrO+BaO); and
BaO(MgO+CaO+SrO+BaO)
are at least 0.1, and
the clad glass composition is substantially free from lead and has a refractive index in a range of 1.56 to 1.68, and
a core glass composition that forms a core has a different composition from the clad glass composition, and comprises the following components, indicated by mol %:
40 to 65% SiO2;
1 to 10% TiO2;
0 to 20% B2O3;
0 to 10% Al2O3;
5 to 12% Li2O;
5 to 15% Na2O;
0 to 16% MgO;
0 to 15% CaO;
0.1 to 12% SrO;
0.1 to 12% SrO;
0.1 to 12% BaO;
0 to 3% Cs2O;
0 to 8% ZnO;
0 to 5% Y2O3;
0 to 5% Nb2O5.;
0 to 5% In2O3;
0 to 5% La2O3;
0 to 5% Ta2O5;
0 to 1% SnO2;
0 to 1% Sb2O3; and
0 to 1% As2O3,
where the total of SiO2+TiO2+B2O3+Al2O3 is in a range of 50 to 70 mol %,
the total of Li2O+Na2O is in a range of 10 to 27 mol %,
the molar ratio of Li2ONa2O is in a range of 0.7 to 2, and
the total of MgO+CaO+SrO+BaO is in a range of 5 to 36 mol %,
at least two values selected from the contents by percentage of CaO, SrO, and BaO are in a range of 0.1 to 15 mol %,
at least two molar ratios selected from the group consisting of:
MgO(MgO+CaO+SrO+BaO);
CaO(MgO+CaO+SrO+BaO);
SrO(MgO+CaO+SrO+BaO); and
BaO(MgO+CaO+SrO+BaO)
are at least 0.1, and
the core glass composition is substantially free from lead.
2. The mother glass rod for a gradient-index rod lens according to claim 1, wherein a difference \u0394n (\u0394n=n1\u2212n2) between a refractive index n1 of the core glass composition and a refractive index n2 of the clad glass composition is in a range of \u22120.03 to 0.04.
3. The mother glass rod for a gradient-index rod lens according to claim 1, wherein the mother glass rod has a diameter of 400 \u03bcm or smaller.
4. A gradient-index rod lens obtained by providing a mother glass rod for a gradient-index rod lens according to claim 1 with a refractive index distribution by an ion exchange method.
5. A rod lens array comprising at least two gradient-index rod lenses according to claim 4,
wherein the rod lenses are arrayed and formed into one body, with their optical axes being substantially in parallel with each other.
6. An image processor comprising a rod lens array according to claim 5,
wherein the rod lens array serves as an imaging optical system.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A shaft assembly comprising:
a titanium-aluminide turbine wheel;
a steel shaft having opposite first and second ends, the shaft having a joint surface at the first end for attachment to the turbine wheel; and
a titanium alloy member sandwiched between a surface of the titanium-aluminide turbine wheel and the joint surface of the shaft, the titanium alloy member having a melting temperature of 650\xb0 C. to 750\xb0 C., which is lower than that of the titanium-aluminide turbine wheel and lower than that of the shaft;
the titanium alloy member being heated to cause melting of the titanium alloy member and then being allowed to cool and solidify so as to join the titanium-aluminide turbine wheel to the shaft.
2. The shaft assembly of claim 1, wherein the titanium alloy member comprises a silver-titanium alloy member.