Blazed diffractive optical element and method of manufacturing blazed diffractive optical element

A blazed diffractive optical element comprising:

• a blazed member;
• and
• a layer that is provided on the blazed member,
• wherein a refractive index of the layer is between a refractive index of the blazed member and a refractive index of an ambient environment around the blazed member,
• wherein the ambient environment is anterior chamber aqueous humor in an eye, and
• the refractive index of the layer is between the refractive index of the blazed member and a refractive index of the anterior chamber aqueous humor,
• wherein in a case where the refractive index of the anterior chamber aqueous humor is represented by A, the refractive index of the layer is represented by B, and the refractive index of the blazed member is represented by C, a magnitude relationship of A<B<C is satisfied,
• wherein the blazed member has a serrated surface,
• wherein the serrated surface is formed with a steep slope surface and a gentle slope surface having a gentler gradient than the steep slope surface,
• wherein the blazed member has a reference surface,
• wherein the steep slope surface and the gentle slope surface are surfaces that rise from the reference surface,
• wherein the steep slope surface is perpendicular to the reference surface,
• wherein the layer consists of a plurality of layers where a refractive index increases from the anterior chamber aqueous humor side to the blazed member side,
• wherein in a case where a grating height of the blazed member is represented by h, a thickness of the layer is represented by t, the thickness t is defined as a minimum normal distance between the serrated surface at the steep slope and an anterior chamber aqueous humor-side interface of the layer, and a critical angle is represented by θc, an inequality of h<t·tanθc and an equality of θc=a sin (A/C) are satisfied, and
• wherein the thickness t represents a distance between the serrated surface and the anterior chamber aqueous humor-side interface of the layer, and is uniform between the serrated surface and the anterior chamber aqueous humor-side interface of the layer.

A method of manufacturing a blazed diffractive optical element, the method comprising:

• a step of forming a first blazed member;
• a step of forming an interlayer on a blazed portion of the first blazed member;
• and
• a step of forming a second blazed member that is provided on a side of the interlayer opposite to the first blazed member side and forms a pair with the first blazed member,
• wherein in a case where a refractive index of the first blazed member is represented by Na, a refractive index of the interlayer is represented by N, and a refractive index of the second blazed member is represented by Nb, a magnitude relationship of Na>N>Nb is satisfied,
• wherein the step of forming the interlayer is a step of forming the interlayer by spin coating,
• wherein in a case where a grating height of the first blazed member and the second blazed member is represented by h, a thickness of the interlayer is represented by t, and a critical angle is represented by θc, the interlayer having a thickness that satisfies an inequality of h<t·tanθc and an equality of θc=a sin(Nb/Na) is formed,
• wherein the thickness represents a thickness of the interlayer between the first blazed member and the second blazed member, and
• wherein the interlayer is formed in a film shape such that the thickness is uniform.