Optical article and illumination system for endoscope
View Patent ↗An optical element, wherein axially symmetric or not, an output surface of which contains a plurality of indentations configured to increase a degree of divergence of light that is incident onto such surface through an input surface of the optical element. In one implementation, each of the indentations defines a corresponding aspheric lenslet the plurality of which encircles the central opening in the optical element. The optical element can be configured as a lightguide having the specified output surface. An illumination system for a laparoscope employing such optical element as an addition to the optical fiber bundle of the laparoscope or as a fiber bundle itself that has the specified output surface.
1. A laparoscope comprising:
a tubular lightguide of the laparoscope that has
an annularly-shaped cross-section with first and second radii, and
an output surface that is transverse to an extend of said tubular lightguide;
an optical lens element defined by an optically-transparent annular plate that has an axis of the optical lens element,
a front surface of the optical lens element, said front surface having an outer radius, and
a back surface of the optical lens element, said back surface having an inner radius;
wherein the optical lens element includes a plurality of rotationally-symmetric structure on the back surface;
wherein the outer radius is substantially equal to the first radius and the inner radius is substantially equal to the second radius; and
wherein the front surface is disposed to face the output surface;
and
a screen having an optically-opaque area and a plurality of apertures that are spatially co-registered with the rotationally-symmetric structures,
wherein said screen is disposed between the output surface and the front surface.
2. The laparoscope according to claim 1 , wherein the screen has an annular shape with third and second radii, and wherein the third radius is substantially equal to the outer radius and the fourth radius is substantially equal to the second radius.
3. The laparoscope according to claim 1 ,
wherein said plurality of the rotationally-symmetric structures is dimensioned to form an array of negative lenslets, in the back surface; and
wherein a surface of each of said negative lenslets from the array plurality has a cross-sectional profile represented by an even polynomial function z=Σ m=0 20 C m x 2m to form, from light propagating through the tubular lightguide and the optical lens element entering the front surface, a substantially-uniform distribution of optical power dimensioned as a circle centered at the axis,
wherein x is a coordinate measured along the back surface.
4. A method for fabricating a laparoscope, the method comprising:
providing a tubular lightguide of the laparoscope that has
an annularly-shaped cross-section with first and second radii, and
an output surface that is transverse to an extent of said tubular lightguide;
disposing a front surface of an optical lens element to face the output surface, said front surface having an outer radius,
wherein the optical lens element includes an optically-transparent annular plate
that has an axis of the optical lens element, said front surface, and a back surface that has an inner radius;
and
wherein the outer radius is substantially equal to the first radius and the inner radius is substantially equal to the second radius;
and
positioning a screen having an optically-opaque area between said output surface and said front surface.
5. The method according to claim 4 , wherein said disposing includes disposing the front surface of said optical lens element that has a plurality of rotationally-symmetric structures in said back surface.
6. The method according to claim 5 , wherein said disposing includes disposing said optical lens element wherein a surface of each of said rotationally-symmetric structures defines a negative lenslet that has a cross-sectional profile represented by an even polynomial function z=Σ m=0 20 C m x 2m to form, from light propagating through the tubular lightguide and entering the front surface, a substantially-uniform distribution of optical power dimensioned as a circle centered at the axis,
wherein x is a coordinate measured along the back surface.
7. The method according to claim 4 , wherein said positioning the screen includes positioning the screen that has an annular shape with third and second radii, and wherein the third radius is substantially equal to the outer radius and the fourth radius is substantially equal to the second radius.
8. The method according to claim 4 , wherein said disposing the front surface of the optical lens element includes disposing the front surface in direct contact with the screen.
9. The method according to claim 4 , wherein said disposing the front surface of the optical lens element includes disposing the optical lens element a first surface of which, from the front and back surfaces, is not planar.