# US 7,729,578 B2 · Illuminator method and device

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- Number: US 7,729,578 B2
- Document ID: US7729578B2
- Status: Granted
- Kind: B2
- Application number: 11/891,362
- Filed: 2007-08-10
- Published: 2008-02-14
- Granted: 2010-06-01
- Earliest claimed: 2006-04-18
- Assignees: Upstream Engineering Oy
- Inventors: Ilkka A. Alasaarela; Jussi P. Soukkamäki; Teuvo K. Viljamaa
- Web page: https://patentgrep.com/patent/US7729578B2

## CPC

- F21V 5/046: {the lens having a rotationally symmetrical shape about an axis for transmitting light in a direction mainly perpendicular to this axis, e.g. ring or annular lens with light source disposed inside the ring}
- G02B 19/0028: {refractive and reflective surfaces, e.g. non-imaging catadioptric systems}
- G02B 19/0061: {the light source comprising a LED}
- F21V 7/0091: {using total internal reflection}
- F21V 13/04: the elements being reflectors and refractors {(for vehicle rear lights F21S43/40)}
- F21Y 2115/10: Light-emitting diodes [LED]
- G02B 21/06: Means for illuminating specimens
- F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- F21Y: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED

## Abstract

A first toroidal ray guide defines an axis of revolution and has a toroidal entrance pupil adapted to image light incident on the entrance pupil at an angle to the axis of revolution between 40 and 140 degrees, and it also has a first imaging surface opposite the entrance pupil. A second toroidal ray guide also defines the same axis of revolution and has a second imaging surface adjacent to the first imaging surface. Various additions and further qualities of the ray guides, which form optical channels, are disclosed. In a method light emanating from a source at between 40-140 degrees from an optical axis is received at an entrance pupil of a ray guide arrangement that is circularly symmetric about the optical axis. Then the received light is redirected through the ray guide arrangement to an exit pupil in an average direction substantially parallel to the optical axis.

## Claims

### Claim 1

An apparatus comprising:
at least one ray guide substantially cylindrically symmetrical about an axis;
said at least one ray guide being arranged to substantially image at least a portion of the rays, which emanate from a non-point object towards an entrance pupil of the said at least one ray guide, to an image;
and in each individual cross-sectional plane which includes the said axis and a portion of the entrance pupil, said at least one ray guide being arranged to image an individual subset of the rays which emanate from the non-point object along the individual cross-sectional plane towards a portion of the entrance pupil which is on the individual cross-sectional plane and on one side of the axis to an intermediate image on the individual cross-sectional plane, and to further substantially image the at least a portion of the rays from the intermediate image to an cross-sectional image on the cross-sectional plane, which cross-sectional image substantially coincides with a cross-section of the image at the said individual cross-sectional plane, such that no two said intermediate images of two different individual cross-sectional planes cross each other.

### Claim 2 (depends on 1)

An apparatus of claim 1, wherein said at least one ray guide is arranged such that no ray of the individual subset of rays crosses the axis between the said cross-section of the entrance pupil and the cross-section of the exit pupil of the said at least one ray guiding component which is on the same half of the individual cross-sectional plane in respect to the axis than the said cross-section of the entrance pupil.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the at least one ray guide is arranged to substantially image the entrance pupil to the exit pupil on each of the cross-sectional half planes bounded by the axis.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged to substantially image substantially all rays, which emanate from the non-point object towards the entrance pupil of the said at least one ray guide, to the image.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged such that conjugate points in the entrance pupil and in the exit pupil are spaced from the axis by a substantially equal distance.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged such that any point which is substantially imaged from the non-point object to the image forms a spot on the image such that its root mean square-spot size is substantially smaller than a mean diameter of the image.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the root mean square-spot size is smaller than one fourth of the mean diameter of the image.

### Claim 8 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged such that an average distance from the non-point object to the entrance pupil is substantially larger than a mean distance from the non-point object to the axis.

### Claim 9 (depends on 8)

The apparatus of claim 8; wherein said average distance from the non-point object to the entrance pupil is at least three times larger than the mean distance from the non-point object to the axis.

### Claim 10 (depends on 1)

The apparatus of claim 1, wherein the rays are rays of electromagnetic radiation between ultraviolet and infrared wavelengths.

### Claim 11 (depends on 10)

The apparatus of claim 10, wherein the rays of electromagnetic radiation are rays emitted from a light-emitting diode.

### Claim 12 (depends on 1)

The apparatus of claim 1, which is an illumination component of an image forming system.

### Claim 13 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged such that at least one line between the entrance pupil and a point on the axis, which point is nearest to an average point of the non-point object, forms an angle greater than 35 degrees with the axis.

### Claim 14 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged such that every line between the entrance pupil and a point on the axis, which point is nearest to an average point of the non-point object, forms an angle greater than 30 degrees with the axis.

### Claim 15 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged to change the propagation direction of the at least portion of the rays successively at least in three distinct locations per ray.

### Claim 16 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged to change the propagation direction of the at least portion of the rays successively at no more than five distinct locations per ray.

### Claim 17 (depends on 1)

The apparatus of claim 1, wherein said at least one ray guide is arranged such that the entrance pupil covers a solid angle of at least 0.1 steradians about a point on the axis which is nearest to an average point of the non-point object.

### Claim 18

An apparatus comprising:
at least one ray guiding component substantially cylindrically symmetrical about an axis of revolution;
said at least one ray guiding component being arranged to substantially image at least a portion of the rays, which emanate from a non-point object towards an entrance pupil of the said at least one ray guiding component, to an image;
said at least one ray guiding component being arranged to substantially image the entrance pupil into an exit pupil of the said at least one ray guiding component, such that each point on the entrance pupil is substantially imaged to a projection of the point substantially along the direction of the said axis of revolution on the exit pupil;
said at least one ray guiding component being arranged to have substantially all points of the entrance pupil at approximately a same distance from the object; and
said at least one ray guiding component being arranged so that no path of any meridional ray imaged from the entrance pupil into the exit pupil crosses the said axis of revolution between the entrance pupil and the exit pupil.

### Claim 19 (depends on 18)

The apparatus of claim 18, wherein said at least one ray guiding component is arranged to substantially image substantially all rays, which emanate from the non-point object towards the entrance pupil of the said at least one ray guiding component, to the image.

### Claim 20 (depends on 18)

The apparatus of claim 18, wherein said at least one ray guiding component is arranged such that any point which is substantially imaged from the non-point object to the image forms a spot on the image such that its root mean square-spot size is substantially smaller than a mean diameter of the image.

### Claim 21 (depends on 18)

The apparatus of claim 18, wherein the root mean square-spot size is smaller than one fourth of a mean diameter of the image.

### Claim 22 (depends on 18)

The apparatus of claim 18, wherein said at least one ray guiding component is arranged such that an average distance from the non-point object to the entrance pupil is substantially larger than a mean distance from the object to the axis.

### Claim 23 (depends on 22)

The apparatus of claim 22; wherein said average distance from the non-point object to the entrance pupil is at least three times larger than the mean distance from the non-point object to the axis.

### Claim 24 (depends on 18)

The apparatus of claim 18, wherein the rays are rays of electromagnetic radiation between ultraviolet and infrared wavelengths.

### Claim 25 (depends on 24)

The apparatus of claim 24, wherein the rays of electromagnetic radiation are rays emitted from a light-emitting diode.

### Claim 26 (depends on 18)

The apparatus of claim 18, which is an illumination component of an image forming system.

### Claim 27 (depends on 18)

The apparatus of claim 18, wherein said at least one ray guiding component is arranged such that at least one line between the entrance pupil and the point on the axis, which point is nearest to an average point of the non-point object, forms an angle greater than 35 degrees with the axis.

### Claim 28 (depends on 18)

The apparatus of claim 18, wherein said at least one ray guiding component is arranged such that every line between the entrance pupil and a point on the axis, which point is nearest to an average point of the non-point object, forms an angle greater than 30 degrees with the axis.

### Claim 29 (depends on 18)

The apparatus of claim 18, wherein said at least one ray guiding component is arranged to change the propagation direction of the at least portion of the rays successively at no more than five distinct locations per ray.

### Claim 30 (depends on 18)

The apparatus of claim 18, wherein said at least one ray guiding component is arranged to have length along the axis smaller than a diameter of the exit pupil.

### Claim 31 (depends on 18)

The apparatus of claim 18, wherein said at least one ray guiding component is arranged such that the entrance pupil covers a solid angle of at least 3 steradians about a point on the axis, which point is nearest to an average point of the non-point object.