Multiphoton fluorescence filters

An optical filter comprising:

• a substrate;
• a first plurality of hard-coating layers provided on the substrate and including alternating first and second layers, each first layer having a first refractive index with at least a real first refractive index and each second layer having a second refractive index with at least a real second refractive index, the real second refractive index being greater than the real first refractive index over a wavelength range;
• a second plurality of hard-coating layers provided on the substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a third layer, a first instance of a first group layer, a fourth layer, a second instance of the first group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each first group layer selected from one of a first intermediate index layer and a first Herpin equivalent layer, each first group layer having a first group refractive index with at least a real first group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real first group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the wavelength range;
• and
• a third plurality of hard-coating layers provided on the substrate, the third plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a fifth layer, a first instance of a second group layer, a sixth layer, a second instance of the second group layer, and a second instance of the fifth layer, each fifth layer having a fifth refractive index with at least a real fifth refractive index, each second group layer selected from one of a second intermediate index layer and a second Herpin equivalent layer, each second group layer having a second group refractive index with at least a real second group refractive index, and each sixth layer having a sixth refractive index with at least a real sixth refractive index, the real second group refractive index being greater than the real fifth refractive index and less than the real sixth refractive index over the wavelength range;
• wherein at least one first group layer included in the second plurality of hard-coating layers is the first Herpin equivalent layer, the first Herpin equivalent layer comprising at least one first sub-layer and one second sub-layer, and at least one second group layer included in the third plurality of hard-coating layers is the second Herpin equivalent layer, the second Herpin equivalent layer comprising at least one third sub-layer and one fourth sub-layer, wherein the thickness of each of the first, second, third, and fourth sub-layers is substantially less than the thickness of at least one of the first, second, third, fourth, fifth, and sixth layers, and wherein the first group refractive index of the at least one first group layer is a first effective refractive index and the second group refractive index of the at least one second group layer is a second effective refractive index.

An optical system comprising:

• an optical source configured to output light at a first wavelength toward a sample;
• an optical detector configured to detect light at a second wavelength from the sample;
• and
• an optical filter comprising:
• a substrate;
• a first plurality of hard-coating layers provided on the substrate and including alternating first and second layers, each first layer having a first refractive index with at least a real first refractive index and each second layer having a second refractive index with at least a real second refractive index, the real second refractive index being greater than the real first refractive index over a wavelength range;
• a second plurality of hard-coating layers provided on the substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a third layer, a first instance of a first group layer, a fourth layer, a second instance of the first group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each first group layer selected from one of a first intermediate index layer and a first Herpin equivalent layer, each first group layer having a first group refractive index with at least a real first group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real first group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the wavelength range;
• and
• a third plurality of hard-coating layers provided on the substrate, the third plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a fifth layer, a first instance of a second group layer, a sixth layer, a second instance of the second group layer, and a second instance of the fifth layer, each fifth layer having a fifth refractive index with at least a real fifth refractive index, each second group layer selected from one of a second intermediate index layer and a second Herpin equivalent layer, each second group layer having a second group refractive index with at least a real second group refractive index, and each sixth layer having a sixth refractive index with at least a real sixth refractive index, the real second group refractive index being greater than the real fifth refractive index and less than the real sixth refractive index over the wavelength range;
• wherein the optical filter is configured such that at least some of the light at the second wavelength passes through the optical filter to the optical detector;
• wherein at least one first group layer included in the second plurality of hard-coating layers is the first Herpin equivalent layer, the first Herpin equivalent layer comprising at least one first sub-layer and one second sub-layer, and at least one second group layer included in the third plurality of hard-coating layers is the second Herpin equivalent layer, the second Herpin equivalent layer comprising at least one third sub-layer and one fourth sub-layer, wherein the thickness of each of the first, second, third, and fourth sub-layers is substantially less than the thickness of at least one of the first, second, third, fourth, fifth, and sixth layers, and wherein the first group refractive index of the at least one first group layer is a first effective refractive index and the second group refractive index of the at least one second group layer is a second effective refractive index.

An optical filter comprising:

• a substrate;
• a first plurality of hard-coating layers provided on the substrate and including alternating first and second layers, each first layer having a first refractive index with at least a real first refractive index and each second layer having a second refractive index with at least a real second refractive index, the real second refractive index being greater than the real first refractive index over a wavelength range;
• a second plurality of hard-coating layers provided on the substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a third layer, a first instance of a group layer, a fourth layer, a second instance of the group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each group layer selected from one of an intermediate index layer and a Herpin equivalent layer, each group layer having a group refractive index with at least a real group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the wavelength range;
• wherein the optical filter has an average transmission greater than 80% over a first wavelength range extending from a first wavelength less than or equal to about 380 nm to a second wavelength between about 650 nm and about 720 nm, the optical filter having an average optical density (OD) greater than 5 over a second wavelength range extending from a third wavelength, which is greater than the second wavelength and is between about 680 nm and about 750 nm, to a fourth wavelength greater than or equal to about 1100 nm.

An optical filter comprising:

• a substrate;
• a first plurality of hard-coating layers provided on the substrate and including alternating first and second layers, each first layer having a first refractive index with at least a real first refractive index and each second layer having a second refractive index with at least a real second refractive index, the real second refractive index being greater than the real first refractive index over a wavelength range;
• a second plurality of hard-coating layers provided on the substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a third layer, a first instance of a group layer, a fourth layer, a second instance of the group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each group layer selected from one of an intermediate index layer and a Herpin equivalent layer, each group layer having a group refractive index with at least a real group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the wavelength range;
• wherein the optical filter has an average transmission greater than 80% over a first wavelength range extending from a first wavelength λa to a second wavelength between about λa×650÷380 and about λa×720÷380, the optical filter having an average optical density (OD) greater than 6 over a second wavelength range extending from a third wavelength, which is greater than the second wavelength and is between about λa×680÷380 and about λa×750÷380, to a fourth wavelength equal to about λa×1100÷380, wherein λa is a wavelength between about 300 nm and about 600 nm.

An optical filter comprising:

• a substrate;
• a first plurality of hard-coating layers provided on the substrate and including alternating first and second layers, each first layer having a first refractive index with at least a real first refractive index and each second layer having a second refractive index with at least a real second refractive index, the real second refractive index being greater than the real first refractive index over a wavelength range;
• a second plurality of hard-coating layers provided on the substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a third layer, a first instance of a group layer, a fourth layer, a second instance of the group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each group layer selected from one of an intermediate index layer and a Herpin equivalent layer, each group layer having a group refractive index with at least a real group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the wavelength range;
• wherein at least one group layer included in the second plurality of hard-coating layers is the Herpin equivalent layer, the Herpin equivalent layer comprising at least one first sub-layer and one second sub-layer, and wherein the group refractive index of the at least one group layer is an effective refractive index.

An optical filter comprising:

• a first plurality of hard-coating layers;
• and
• a second plurality of hard-coating layers provided on a substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a first layer, a first instance of a group layer, a second layer, a second instance of the group layer, and a second instance of the first layer, each first layer having a first refractive index with at least a real first refractive index, each group layer selected from one of an intermediate index layer and a Herpin equivalent layer, each group layer having a group refractive index with at least a real group refractive index, and each second layer having a second refractive index with at least a real second refractive index, the real group refractive index being greater than the real first refractive index and less than the real second refractive index over a range of wavelengths;
• wherein the optical filter has an average transmission greater than 80% over a first wavelength range extending from a first wavelength λa to a second wavelength between about λa×650÷380 and about λa×720÷380, the optical filter having an average optical density (OD) greater than 6 over a second wavelength range extending from a third wavelength, which is greater than the second wavelength and is between about λa×680÷380 and about λa×750÷380, to a fourth wavelength equal to about λa×1100÷380, wherein λa is a wavelength between about 300 nm and about 600 nm.

An optical filter comprising:

• a first plurality of hard-coating layers;
• and
• a second plurality of hard-coating layers provided on a substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a first layer, a first instance of a group layer, a second layer, a second instance of the group layer, and a second instance of the first layer, each first layer having a first refractive index with at least a real first refractive index, each group layer selected from one of an intermediate index layer and a Herpin equivalent layer, each group layer having a group refractive index with at least a real group refractive index, and each second layer having a second refractive index with at least a real second refractive index, the real group refractive index being greater than the real first refractive index and less than the real second refractive index over a range of wavelengths;
• wherein the optical filter has a transmission characteristic as a function of wavelength, the transmission characteristic having an average transmission greater than or equal to 80% over a first band of wavelengths, the transmission characteristic having a first blocking level over a second band of wavelengths, and a second blocking level over a third band of wavelengths, the first blocking level over the second band of wavelengths being associated with a first transmission characteristic of the first plurality of hard-coating layers, and the second blocking level over the third band of wavelengths being associated with a second transmission characteristic of the second plurality of hard-coating layers, each of the first and second transmission characteristics having an average transmission greater than or equal to 80% over the first band of wavelengths;
• wherein at least one group layer included in the plurality of hard-coating layers is the Herpin equivalent layer, the Herpin equivalent layer comprising at least one first sub-layer and one second sub-layer, and wherein the group refractive index of the at least one group layer is an effective refractive index.

An optical filter comprising:

• a first plurality of hard-coating layers;
• and
• a second plurality of hard-coating layers provided on a substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a first layer, a first instance of a group layer, a second layer, a second instance of the group layer, and a second instance of the first layer, each first layer having a first refractive index with at least a real first refractive index, each group layer selected from one of an intermediate index layer and a Herpin equivalent layer, each group layer having a group refractive index with at least a real group refractive index, and each second layer having a second refractive index with at least a real second refractive index, the real group refractive index being greater than the real first refractive index and less than the real second refractive index over a range of wavelengths;
• a third plurality of hard-coating layers provided on a second substrate, the third plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a third layer, a first instance of a second group layer, a fourth layer, a second instance of the second group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each second group layer selected from one of a second intermediate index layer and a second Herpin equivalent layer, each second group layer having a second group refractive index with at least a real second group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real second group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the range of wavelengths;
• wherein the optical filter has a transmission characteristic as a function of wavelength, the transmission characteristic having an average transmission greater than or equal to 80% over a first band of wavelengths, the transmission characteristic having a first blocking level over a second band of wavelengths, and a second blocking level over a third band of wavelengths, the first blocking level over the second band of wavelengths being associated with a first transmission characteristic of the first plurality of hard-coating layers, and the second blocking level over the third band of wavelengths being associated with a second transmission characteristic of the second plurality of hard-coating layers, each of the first and second transmission characteristics having an average transmission greater than or equal to 80% over the first band of wavelengths;
• wherein the first band of wavelengths extend from a first wavelength λa to a second wavelength between about λa×650÷380 and about λa×720÷380;
• wherein the second blocking level has an average optical density (OD) greater than 5 and the third band of wavelengths extend from a third wavelength, which is greater than the second wavelength and is between about λa×680÷380 and about λa×750÷380, to a fourth wavelength equal to about λa×1100÷380;
• and
• wherein λa is a wavelength between about 300 nm and about 600 nm.

An optical filter comprising:

• a first plurality of hard-coating layers;
• and
• a second plurality of hard-coating layers provided on a substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a first layer, a first instance of a group layer, a second layer, a second instance of the group layer, and a second instance of the first layer, each first layer having a first refractive index with at least a real first refractive index, each group layer selected from one of an intermediate index layer and a Herpin equivalent layer, each group layer having a group refractive index with at least a real group refractive index, and each second layer having a second refractive index with at least a real second refractive index, the real group refractive index being greater than the real first refractive index and less than the real second refractive index over a range of wavelengths;
• a third plurality of hard-coating layers provided on a second substrate, the third plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a third layer, a first instance of a second group layer, a fourth layer, a second instance of the second group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each second group layer selected from one of a second intermediate index layer and a second Herpin equivalent layer, each second group layer having a second group refractive index with at least a real second group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real second group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the range of wavelengths;
• wherein the optical filter has a transmission characteristic as a function of wavelength, the transmission characteristic having an average transmission greater than or equal to 80% over a first band of wavelengths, the transmission characteristic having a first blocking level over a second band of wavelengths, and a second blocking level over a third band of wavelengths, the first blocking level over the second band of wavelengths being associated with a first transmission characteristic of the first plurality of hard-coating layers, and the second blocking level over the third band of wavelengths being associated with a second transmission characteristic of the second plurality of hard-coating layers, each of the first and second transmission characteristics having an average transmission greater than or equal to 80% over the first band of wavelengths;
• wherein the transmission characteristic has a third blocking level over a fourth band of wavelengths, the fourth band of wavelengths being associated with the third plurality of hard-coating layers, and
• wherein the first band of wavelengths extends from about 300 nm to about 700 nm, the second band of wavelengths extends from about 700 nm to about 840 nm, the third band of wavelengths extends from about 840 nm to about 950 nm, and the fourth band of wavelengths extends from about 950 nm to about 1100 nm.

An optical filter comprising:

• a first plurality of hard-coating layers;
• and
• a second plurality of hard-coating layers provided on a substrate, the second plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a first layer, a first instance of a group layer, a second layer, a second instance of the group layer, and a second instance of the first layer, each first layer having a first refractive index with at least a real first refractive index, each group layer selected from one of an intermediate index layer and a Herpin equivalent layer, each group layer having a group refractive index with at least a real group refractive index, and each second layer having a second refractive index with at least a real second refractive index, the real group refractive index being greater than the real first refractive index and less than the real second refractive index over a range of wavelengths;
• a third plurality of hard-coating layers provided on a second substrate, the third plurality of hard-coating layers including at least one repeated sequence consisting of:
• a first instance of a third layer, a first instance of a second group layer, a fourth layer, a second instance of the second group layer, and a second instance of the third layer, each third layer having a third refractive index with at least a real third refractive index, each second group layer selected from one of a second intermediate index layer and a second Herpin equivalent layer, each second group layer having a second group refractive index with at least a real second group refractive index, and each fourth layer having a fourth refractive index with at least a real fourth refractive index, the real second group refractive index being greater than the real third refractive index and less than the real fourth refractive index over the range of wavelengths;
• wherein the optical filter has a transmission characteristic as a function of wavelength, the transmission characteristic having an average transmission greater than or equal to 80% over a first band of wavelengths, the transmission characteristic having a first blocking level over a second band of wavelengths, and a second blocking level over a third band of wavelengths, the first blocking level over the second band of wavelengths being associated with a first transmission characteristic of the first plurality of hard-coating layers, and the second blocking level over the third band of wavelengths being associated with a second transmission characteristic of the second plurality of hard-coating layers, each of the first and second transmission characteristics having an average transmission greater than or equal to 80% over the first band of wavelengths;
• wherein at least one group layer included in the plurality of hard-coating layers is the Herpin equivalent layer, the Herpin equivalent layer comprising at least one first sub-layer and one second sub-layer;
• wherein at least one second group layer included in the second plurality of hard-coating layers is the second Herpin equivalent layer, the second Herpin equivalent layer comprising at least one third sub-layer and one fourth sub-layer;
• and
• wherein the group refractive index of the at least one group layer is an effective refractive index and the second group refractive index of the at least one second group layer is a second effective refractive index.