Optical diffraction element and endoscope

Abstract

Provided is an optical diffraction element (1) in which two optical material layers (2, 3) comprising cured resin having different energies are laminated, and a relief pattern (4) is formed at the interface of the two optical material layers (2, 3), the optical diffraction element (1) satisfying the following conditional expressions: 0.01<d2 / d1<0.2 (1); 0.05<d1 / [phi]E<1.0 (2); 0.0005<d2 / [phi]E<0.1 (3); d1 is the central thickness (mm) of the one optical material layer (2) that is cured first, d2 is the central thickness (mm) of the other optical material layer (3) that is subsequently cured, and [phi]E is the effective diameter (mm) of the relief pattern (4).

Description

technical field [0001] The present invention relates to a diffractive optical element and an endoscope. Background technique [0002] Conventionally, as a diffractive optical element, since it has the characteristic of being able to correct the chromatic aberration of the optical system favorably, it has been disclosed in the following documents (for example, refer to Patent Documents 1 to 7). [0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2-179605 [0004] Patent Document 2: Japanese Patent Application Laid-Open No. 11-271513 [0005] Patent Document 3: Japanese Patent Application Laid-Open No. 11-287904 [0006] Patent Document 4: Japanese Unexamined Patent Publication No. 2007-273012 [0007] Patent Document 5: Japanese Patent Laid-Open No. 2009-197217 [0008] Patent Document 6: Japanese Unexamined Patent Publication No. 2005-107298 [0009] Patent Document 7: International Publication No. 2007 / 111077 [0010] However, the diffractive optical...

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Problems solved by technology

As a result, high diffraction efficiency of the first-order diffracted light (hereinafter, simply referred to as "diffraction efficiency") can be realized in a wide wavelength region, but since one of the two-layer optical elements is made of glass material, There are disadvantages such as difficult processing of relief patterns, insufficient mass productivity, and high cost

[0012] In addition, since the diffractive optical elements of Patent Documents 4 to 7 are made of resin, they are excellent in processability and mass productivity, and can be manufactured at low cost. However, the condition of the center thickness is not suitable, and warping and peeling tend to occur during the manufacturing process. such a bad situation

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