Diffractive element, method of manufacturing the same, optical pickup device, and optical disc apparatus

1. A diffractive element on which two wavelengths of light are incident from a light source, the diffractive element transmitting one of the two wavelengths of light to one type optical disc, the diffractive element splitting the other wavelength of light and emitting the split light to another type optical disc, the diffractive element comprising:

a first member including a first resin and having a predetermined refractive index, and

a second member having the same refractive index as the first member in the one wavelength of light and having a refractive index different from the first member in the other wavelength of light,

wherein the first member and the second member are alternately arranged in a right-and-left direction with respect to an incidence direction of the two wavelengths of light, thereby constituting a diffraction grating, and

wherein the second member includes organic matter having optical absorption in a predetermined wavelength range and a second resin to dissolve the organic matter at a molecular level so as to form the refractive index of the second member, wherein the organic matter is a dye, not a pigment.

2. The diffractive element according to claim 1 , wherein the one wavelength of light is laser light for DVDs.

3. The diffractive clement according to claim 1 , wherein the other wavelength of light is laser light for CDs.

4. The diffractive element according to claim 1 , wherein the second member is cured without using ultraviolet rays.

5. The diffractive element according to claim 4 , wherein the second member is cured by heat.

6. The diffractive element according to claim 1 , wherein the first resin of the first member is a resin which has no optical absorption in the predetermined wavelength range, whereby the predetermined refractive index of the first member is formed.

7. The diffractive element according to claim 1 , wherein the predetermined wavelength range is a range having a shorter wavelength than the wavelength of a shorter wavelength of light of the two wavelengths of light.

8. The diffractive element according to claim 1 , further comprising a first transparent substrate and a second transparent substrate,

wherein the diffraction grating is formed on the first transparent substrate, and the diffraction grating is inserted between the first transparent substrate and the second transparent substrate and bonded thereto.

9. The diffractive element according to claim 1 , wherein at least one of the first resin and the second resin is an adhesive.

10. The diffractive element according to claim 1 , further comprising a first transparent substrate,

wherein the diffraction grating is formed on the first transparent substrate, and either the first member or the second member is in non-contact with the first transparent substrate in at least a region constituting the diffraction grating.

11. The diffractive element according to claim 1 , wherein the first member includes the first resin which dissolves, at a molecular level, the organic matter in which at least a portion of an optical absorption property in the predetermined wavelength range is lost, and does not have optical absorption in a predetermined wavelength range.

12. The diffractive element according to claim 11 , wherein the first resin and the second resin are the same, the organic matter before at least a portion of an optical absorption property of the first member is lost and the organic matter of the second member are the same, and the condensation of the organic matter included in the first member and the condensation of the organic matter included in the second member are equal to each other.

13. A diffractive element on which two wavelengths of light are incident from a light source, the diffractive element transmitting one of the two wavelengths of light to one type optical disc, the diffractive element splitting the other wavelength of light and emitting the split light to another type optical disc, the diffractive element comprising:

a first member including a first resin and having a predetermined refractive index, and

a second member having the same refractive index as the first member in the one wavelength of light and having a refractive index different from the first member in the other wavelength of light,

wherein the first member and the second member are alternately arranged in a right-and-left direction with respect to an incidence direction of the two wavelengths of light, thereby constituting a diffraction grating,

wherein the second member includes a second resin to dissolve organic matter having optical absorption in a predetermined wavelength range at a molecular level so as to form the refractive index of the second member, and

wherein the predetermined wavelength range is a range having a longer wavelength than the wavelength of a longer wavelength of light of the two wavelengths of light.

14. A diffractive element on which two wavelengths of light are incident from a light source, the diffractive element transmitting one of the two wavelengths of light to one type optical disc, the diffractive element splitting the other wavelength of light and emitting the split light to another type optical disc, the diffractive element comprising:

a first member including a first resin and having a predetermined refractive index, and

a second member having the same refractive index as the first member in the one wavelength of light and having a refractive index different from the first member in the other wavelength of light,

wherein the first member and the second member are alternately arranged in a right-and-left direction with respect to an incidence direction of the two wavelengths of light, thereby constituting a diffraction grating,

wherein the second member includes a second resin to dissolve organic matter having optical absorption in a predetermined wavelength range at a molecular level so as to form the refractive index of the second member, and

wherein at least one of the first member and the second member has a water absorption coefficient of 2% or less.

15. A diffractive element on which laser light for DVDs and laser light for CDs are incident from a laser light source and that transmits the laser light for DVDs and splits the laser light for CDs and emits the split laser light to an optical disc, the diffractive element comprising:

a first member including a first resin and having a predetermined refractive index, and

a second member having the same refractive index as the first member in the laser light for DVDs and having a refractive index different from the first member in the laser light for CDs,

wherein the first member and the second member are alternately arranged in a horizontal direction to an incidence direction of the two wavelengths of light, thereby constituting a diffraction grating, and

wherein the second member includes organic matter having optical absorption in a predetermined wavelength range and a second resin to dissolve the organic matter at a molecular level so as to form the refractive index of the second member, wherein the organic matter is a dye, not a pigment.

16. An optical pickup device comprising a laser light source that emits laser light for DVDs and laser light for CDs and a diffractive element that transmits the laser light for DVDs and splits the laser light for CDs and emits the split laser light to an optical disc, the diffractive element including:

a first member including a first resin and having a predetermined refractive index, and

a second member having the same refractive index as the first member in the laser light for DVDs and having a refractive index different from the first member in the laser light for CDs,

wherein the first member and the second member are alternately arranged in a horizontal direction to an incidence direction of the two wavelengths of light, thereby constituting a diffraction grating, and

wherein the second member includes organic matter having optical absorption in a predetermined wavelength range and a second resin to dissolve the organic matter at a molecular level so as to form the refractive index of the second member, wherein the organic matter is a dye, not a pigment.

17. An optical disc apparatus comprising a laser light source that emits laser light for DVDs and laser light for CDs and a diffractive element that transmits the laser light for DVDs and splits the laser light for CDs and emits the split laser light to an optical disc, the diffractive element including:

a first member including a first resin and having a predetermined refractive index, and

a second member having the same refractive index as the first member in the laser light for DVDs and having a refractive index different from the first member in the laser light for CDs,

wherein the first member and the second member are alternately arranged in a horizontal direction to an incidence direction of the two wavelengths of light, thereby constituting a diffraction grating, and

wherein the second member includes organic matter having optical absorption in a predetermined wavelength range and a second resin to dissolve the organic matter at a molecular level so as to form the refractive index of the second member, wherein the organic matter is a dye, not a pigment.