Laminated diffractive optical element

摘要

A laminated diffractive optical element including a colorant-containing first layer having a diffraction grating surface with a grating height X and a second layer closely stacked on the diffraction grating surface of the first layer, wherein the relation of internal transmittances Tλ, a and Tλ, b of a material (a) for forming the first layer and a material (b) for forming the second layer satisfies the following (Formula 1) and the relation of the maximum and minimum internal transmittances Tλ, MAX and Tλ, MIN of the laminated diffractive optical element satisfies the following Formula (2):
2.0%≦|Tλ, a−Tλ, b|  (Formula 1)Tλ, MAX−Tλ, MIN≦8.0%   (Formula 2)
This reduces shading on the image surface resulting from the difference in transmittance of the optical element to provide a laminated diffractive optical element having reduced variation in transmittance.

主权项

1. A laminated diffractive optical element comprising:
a first layer having a diffraction grating surface with a grating height X; and a second layer closely stacked on the diffraction grating surface of the first layer, wherein where T λ, a is an internal transmittance of a material (a) that the first layer consists of, where the material has a thickness X, and Tλ, b is an internal transmittance of a material (b) that the second layer consists of, where the material has a thickness X, each internal transmittance being an internal transmittance for at least one specific wavelength within the range of 450 nm ≦λ≦650 nm of a light beam with a wavelength λ, the following relationship is satisfied:
2.0%≦|Tλ, a−Tλ, b|  (Formula 1) wherein where Tλ, MAX is an internal transmittance of the element at a part where the transmittance reaches a maximum for a light beam with a wavelength λwithin the range of 450 nm ≦λ≦650 nm, and Tλ, MIN is an internal transmittance of the element at a part where the transmittance reaches a minimum for a light beam with a wavelength λwithin the range of 450 nm ≦λ≦650 nm, the following relationship is satisfied:
Tλ, MAX−Tλ, MIN≦8.0%   (Formula 2), and wherein X satisfies the following relationship: 0.01 μm ≦X≦100 μm.