MEASUREMENT LIGHT SOURCE AND MEASURING ARRANGEMENT FOR DETECTING A REFLECTION SPECTRUM

Abstract

The present invention relates to a measurement light source for generating measurement light with a uniform spatial illumination intensity distribution. The measurement light source comprises a solid block, in which an illumination space, a light-forming space and a light exit space are each formed as a hollow space in the block and have a diffusely reflecting inner surface. The illumination space opens into the light-forming space. The light-forming space opens into the light exit space. At least one light source is at least partially arranged in the illumination space in order to generate light. The light exit space has a light exit. According to the invention, an axis of the illumination space and an axis of the light exit space are arranged at a distance from one another. The light-forming space is designed for a reversal of a light propagation direction. The invention also relates to a measuring arrangement for detecting at least an absolute reflection spectrum of a sample. The measuring arrangement is used in particular for the spectroscopic examination of surfaces in production processes in order to determine the color or gloss of surfaces, for example.

Claims

1. A measurement light source; comprising a solid block, in which an illumination space, a light shaping space, and a light exit space are each formed as a cavity in the block and have a diffusely reflective inner surface; wherein the illumination space opens into the light shaping space; wherein the light shaping space (12) opens into the light exit space; wherein at least one light source (07) for generating light is at least partially arranged in the illumination space; wherein the light exit space has a light exit wherein an axis of the illumination space and an axis of the light exit space are arranged at a distance from one another; and wherein the light shaping space is designed for a reversal of a light propagation direction.

2. The measurement light source as claimed in claim 1, wherein the illumination space is designed for light propagation in a first light propagation direction, and in that the light exit space is designed for light propagation in a second light propagation direction, wherein the first light propagation direction and the second light propagation direction are aligned opposite one another.

3. The measurement light source as claimed in claim 1, wherein the light shaping space connects the illumination space with the light exit space in a U-shaped or V-shaped manner.

4. The measurement light source as claimed in claim 1, wherein the axis of the illumination space and the axis of the light exit space are arranged parallel to one another, wherein the illumination space and the light exit space have the same axial position.

5. The measurement light source as claimed in claim 4, wherein the illumination space, the light shaping space and the light exit space form a U shape or a V shape, wherein the illumination space and the light exit space each form a leg of the U shape or the V shape.

6. The measurement light source as claimed in claim 1, wherein a homogenizer element with a diffusely reflective illumination surface, which is arranged in the axis of the light exit space and is arranged perpendicular to that axis, is arranged at a transition from the light shaping space to the light exit space.

7. The measurement light source as claimed in claim 6, wherein the homogenizer element is mounted on a web, which is arranged in a central plane of the light exit space.

8. The measurement light source as claimed in claim 1, wherein the illumination space has at least one light entry in which the at least one light source is at least partially arranged.

9. The measurement light source as claimed in claim 8, wherein the illumination space has two of the light entries or two groups of the light entries, which are arranged one next to the other.

10. The measurement light source as claimed in claim 9, wherein at least one of the light sources (07) is at least partially arranged in each of the light entries or in each of the groups of the light entries.

11. The measurement light source as claimed in claim 10, wherein the at least one light source is arranged in the form of a halogen lamp in a first of the light entries or in a first of the groups of the light entries, wherein the plurality of light sources are arranged in the form of a plurality of LEDs in a second of the light entries or in a second of the groups of the light entries.

12. The measurement light source as claimed in claim 9, wherein the solid block comprises three sub-blocks, which are firmly connected to one another, wherein a connecting plane between a first of the three sub-blocks and a central second of the three sub-blocks intersects the first light entry, wherein a connecting plane between the central second of the three sub-blocks and a third of the three sub-blocks intersects the second light entry, and wherein the light exit is formed in the central second sub-block.

13. The measurement light source as claimed in claim 1, wherein the solid block has the basic shape of a cuboid, which has two beveled edges that form outer surfaces of the light shaping space.

14. The measurement light source as claimed in claim 1, wherein the solid block has outer edges, the lengths of which are not greater than 90 mm.

15. A measurement arrangement for capturing an absolute reflection spectrum of a sample; comprising: a measurement light source as claimed in claim 1; an optical receiver for receiving measurement light, which is arranged opposite the measurement light source; a first mirror, which is arranged on an axis of the light exit and is aligned to reflect the measurement light emerging from the light exit; and a second mirror, which is arranged on an axis of the optical receiver and is aligned toward the optical receiver for reflecting reflected measurement light.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Further details and developments of the invention will become apparent from the following description of preferred embodiments of the invention, with reference being made to the drawing. The figures show:

[0053] FIG. 1 is a side view of a preferred embodiment of a measurement light source according to the invention;

[0054] FIG. 2 is the measurement light source shown in FIG. 1 in a view from above;

[0055] FIG. 3 is the measurement light source shown in FIG. 1 in a first cross-sectional view;

[0056] FIG. 4 is the measurement light source shown in FIG. 1 in a second cross-sectional view;

[0057] FIG. 5 is the measurement light source shown in FIG. 1 in a third cross-sectional view;

[0058] FIG. 6 is the measurement light source shown in FIG. 1 in a perspective sectional view;

[0059] FIG. 7 is a simplified sectional view of a preferred embodiment of a measurement arrangement according to the invention during a bypass measurement;

[0060] FIG. 8 is the measurement arrangement shown in FIG. 7 during a transmission measurement;

[0061] FIG. 9 is the measurement arrangement shown in FIG. 7 during a reflection measurement; and

[0062] FIG. 10 is the measurement arrangement shown in FIG. 7 during a dark measurement.

DETAILED DESCRIPTION OF THE INVENTION

[0063] FIG. 1 shows a side view of a preferred embodiment of a measurement light source according to the invention. The measurement light source comprises a solid block 01 made of PTFE. The block 01 consists of a first sub-block 02, a second sub-block 03, and a third sub-block 04, which are permanently connected to one another or are monolithic. The block 01 has two light entries 06 arranged one next to the other, in each of which a light source 07 (shown in FIG. 6) is arranged. The block 01 additionally has a light exit 08, from which the light generated by the measurement light source emerges.

[0064] Section marks AA for a cross-sectional view shown in FIG. 3 and section marks BB for a cross-sectional view shown in FIG. 4 are also shown.

[0065] FIG. 2 shows the measurement light source shown in FIG. 1 in a view from above. Section marks CC for a cross-sectional view shown in FIG. 5 are shown.

[0066] FIG. 3 shows the measurement light source shown in FIG. 1 in a first cross-sectional view AA. This cross-sectional view shows the interior of the block 01, specifically an illumination space 11, a light shaping space 12, and a light exit space 13, which are each formed by a cavity in the block 01. The illumination space 11, the light shaping space 12, and the light exit space 13 have a diffusely reflective surface with a reflectance of at least 98% in the entire light spectrum. The light entry 06 forms an entrance into the illumination space 11. The illumination space 11 opens into the light shaping space 12. The light shaping space 12 opens into the light exit space 13. The light shaping space 12 represents a U-shaped connection between the illumination space 11 and the light exit space 13. As a result, the illumination space 11 and the light exit space 13 are arranged one above the other in a space-saving manner. The light shaping space 12 is arranged laterally next to the illumination space 11 and the light exit space 13.

[0067] FIG. 4 shows the measurement light source shown in FIG. 1 in a second cross-sectional view BB. In this cross-sectional view, the illumination space 11, the light shaping space 12, and the light exit space 13 are again shown, wherein they have a smaller cross section in comparison with the representations in FIG. 3. In this cross-sectional view, a homogenizer element 14 is shown in the form of a spherical plate, which is located in the light exit space 13 and is arranged opposite the light exit 08 (shown in FIG. 3).

[0068] FIG. 5 shows the measurement light source shown in FIG. 1 in a third cross-sectional view CC. In this cross-sectional view, the light entries 06 and the light exit 08 are shown, among other things.

[0069] FIG. 6 shows the measurement light source shown in FIG. 1 in a perspective sectional view. In this perspective sectional view, the spatial dimensions of the illumination space 11, the light shaping space 12, and the light exit space 13 are shown. One of the two light sources 07, which in the embodiment shown are formed, for example, by halogen lamps, is arranged in each of the two light entries 06. The two light sources 07 give rise to a two-channel design of the measurement light source. Accordingly, the illumination space 11, the light shaping space 12, and the light exit space 13 have a corresponding extent perpendicular to the cross-sectional plane shown here, i.e. the illumination space 11, the light shaping space 12, and the light exit space 13 and also the measurement light source in their entirety have an increased width for the two-channel design.

[0070] In this perspective sectional view, the homogenizer element 14 is additionally shown. The homogenizer element 14 has two lateral rectangular extensions 17, which prevent light from the two channels, which was only reflected a few times, from entering the light exit space 13. The homogenizer element 14 is held in the central second sub-block 03 by a web 18.

[0071] FIG. 7 shows a simplified sectional view of a preferred embodiment of a measurement arrangement according to the invention during a bypass measurement. The measurement arrangement has the measurement light source shown in FIG. 1, comprising, among other things, the block 01 with the illumination space 11, the light shaping space 12, and the light exit space 13 and also the light entries 06 and the light exit 08. The measurement light source additionally comprises a lens element 20 for enlarging the beam of the measurement light emerging from the light exit 08. The measurement arrangement comprises a first mirror 21, on which the measurement light that has passed through the lens element 20 is incident. The first mirror 21 is spherically curved and is arranged in a fixed manner. The measurement arrangement additionally comprises a second mirror 22, which is directed onto an optical receiver 23. Lens elements 24, which focus the reflected measurement light, are arranged upstream of the optical receiver 23. The measurement arrangement additionally comprises a third mirror 26, which is adjustable in its alignment and is shown in a first position 27, in a second position 28, in a third position 29, and in a fourth position 31.

[0072] A sample (not shown) is to be arranged in a sample plane 32.

[0073] The measurement arrangement further comprises a black standard 33 and a counter mirror 34, which are arranged below the sample plane 32.

[0074] A beam path 36 of the measurement light is shown, which occurs during the bypass measurement in order to enable a 100% white measurement, whereby the measurement arrangement can be adjusted to 100% white of the measurement light source. Accordingly, the first position 27 of the third mirror 26 is used for a bypass measurement.

[0075] FIG. 8 shows the measurement arrangement shown in FIG. 7 during a transmission measurement. A beam path 37 of the measurement light is shown, which occurs during this transmission measurement. The beam path 37 passes through the sample (not shown) in the sample plane 32 and is reflected at the counter mirror 34 and at the second mirror 22. The third mirror 26 is in its second position 28, as a result of which it releases the beam path 37. Accordingly, the second position 28 of the third mirror 26 is used for a transmission measurement.

[0076] FIG. 9 shows the measurement arrangement shown in FIG. 7 during a reflection measurement. A beam path 38 of the measurement light is shown, which occurs during this reflection measurement. The beam path 38 is reflected by the sample (not shown) in the sample plane 32 and at the third mirror 26, which is in its third position 29. Accordingly, the third position 29 of the third mirror 26 is used for a reflection measurement.

[0077] FIG. 10 shows the measurement arrangement shown in FIG. 7 during a dark measurement. A beam path 39 is shown, which symbolizes that the optical receiver 23 is directed toward the black standard 33 via the third mirror 26, which is in the third position 29. Accordingly, the third position 29 of the third mirror 26 is also used for a dark measurement.