Diffractive optical element, optical system and optical apparatus

An optical system comprising:

• a diffractive optical element,
• wherein the diffractive optical element comprising:
• a glass material;
• a resin material whose dn/dT representing a refractive index variation with temperature is larger than that of the glass material, the resin material being in close contact with or facing the glass material;
• and
• a diffractive grating formed at a close contact portion or a facing portion between the glass material and the resin material,
• wherein the resin material is a mixture material of (a) a resin base material, (b) first fine particles formed of a first material whose dn/dT satisfies a condition of dn/dT≧−1×10−5(/° C.) and (c) second fine particles formed of a second material whose Abbe constant is lower than that of the glass material.

An optical apparatus comprising:

• an optical system including a diffractive optical element,
• wherein the diffractive optical element comprising:
• a glass material;
• a resin material whose dn/dT representing a refractive index variation with temperature is larger than that of the glass material, the resin material being in close contact with or facing the glass material;
• and
• a diffractive grating formed at a close contact portion or a facing portion between the glass material and the resin material,
• wherein the resin material is a mixture material of (a) a resin base material, (b) first fine particles formed of a first material whose dn/dT satisfies a condition of dn/dT≧−1×10−5(/° C.) and (c) second fine particles formed of a second material whose Abbe constant is lower than that of the glass material.