1. A method of forming a membrane in a plurality of through-channels disposed in a substrate, the method comprising the steps of:
a. providing the substrate to a chamber, the substrate having a first end, a second end, and a plurality of through-channels extending through the substrate from the first end to the second end, wherein the chamber has an inlet section below the substrate, a midsection supporting the substrate and separating the substrate from the inlet section, and an outlet section, wherein the substrate is disposed in the midsection such that the first end is, adjacent to and in fluid communication with the inlet section and the second end is adjacent to and in fluid communication with the outlet section, wherein the chamber is oriented vertically such that the inlet section is located at the bottom of the chamber below the midsection and the outlet section is located at the top of the chamber above the midsection;
b. providing a liquid precursor to the inlet section, wherein the liquid precursor comprises membrane-forming materials;
c. providing a pressure differential between the inlet section and the outlet section, wherein the pressure differential causes the liquid precursor to flow uniformly through the plurality of through-channels; and
d. forming the membrane on a surface of the plurality of channels.
2. The method according to claim 1, wherein the liquid precursor comprises a plurality of solid particles, and wherein the step of forming the membrane on a surface of the plurality of channels comprises:
a. transporting the plurality of solid particles in the precursor liquid to the surface of at least a portion of the plurality of through-channels; and
b. depositing the plurality of solid particles on the surface to form the membrane.
3. The method according to claim 1, wherein the step of forming the membrane on a surface of the plurality of through-channels comprises:
a. transporting the liquid precursor to the surface of at least a portion of the plurality of through-channels; and
b. reacting the membrane-forming materials with the surface or each other to form the membrane.
4. The method according to claim 1, wherein the liquid precursor flows through the plurality of through-channels at a predetermined linear velocity.
5. The method according to claim 4, wherein the predetermined linear velocity is in a range from about 0.01 cms to about 200 cms.
6. The method according to claim 5, wherein the linear flow velocity is in a range from about 1 cms up to about 200 cms.
7. The method according to claim 1, wherein the step of providing the pressure differential between the inlet section and the outlet section comprises providing a pressure differential between the inlet section and the outlet section in a range from about 1,000 Pa up to about 1,000,000 Pa.
8. The method according to claim 1, wherein each of the through-channels has a diameter of less than about 3 mm.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An endoscope objective optical system comprising in order from an object side:
a first lens formed of a plano-concave lens having a concave surface facing an image side;
a second lens formed of a plano-concave lens having a concave surface facing the object side;
an aperture stop; and
a third lens formed of a plano-convex lens having a plane surface facing the object side,
the endoscope objective optical system satisfying the following conditional expressions (1) to (3):
0.7\u2266|fabf|\u22660.9 \u2003\u2003(1)
1.7\u2266|fefab|\u22662 \u2003\u2003(2)
2\u2266fbfa\u22664 \u2003\u2003(3)
where f represents a focal length of the entire system,
fa represents a focal length of the first lens,
fb represents a focal length of the second lens,
fe represents a focal length of the third lens, and
fab represents a combined focal length from the first lens to the second lens.
2. The endoscope objective optical system according to claim 1, satisfying the following conditional expression (4):
0.9\u2266NaNb\u22661 \u2003\u2003(4)
where Na represents a refractive index at a d-line of a glass material forming the first lens, and
Nb represents a refractive index at a d-line of a glass material forming the second lens.