Multi-modal wide-angle illumination employing a compound beam combiner

Patent metadata

Field	Value
Publication number	US-11977211-B2
Application number	US-202017441279-A
Country	US
Kind code	B2
Filing date	Jul 9, 2020
Priority date	Jul 11, 2019
Publication date	May 7, 2024
Grant date	May 7, 2024

Abstract

Provided is an optical apparatus that includes an illumination assembly which include an extended radiation source emitting radiation with a controllable spatial distribution and telecentric condensing optics, configured to receive and project the emitted radiation with a numerical aperture exceeding 0.3 along a first optical axis onto a field and an imaging assembly that includes a sensor and objective optics configured to image the field along a second optical axis onto the sensor and also a prism combiner positioned between the field and the condensing and objective optics which is configured to combine the first and second optical axes, while reflecting at least one of the optical axes multiple times within the prism combiner.

First claim

The invention claimed is:

1. An optical apparatus, comprising:
an illumination assembly, comprising:
an extended radiation source emitting radiation with a controllable spatial distribution; and
telecentric condensing optics, configured to receive and project the emitted radiation with a numerical aperture exceeding 0.3 along a first optical axis onto a field;

an imaging assembly comprising a sensor and objective optics configured to image the field along a second optical axis onto the sensor; and
a prism combiner positioned between the field and the telecentric condensing optics and the objective optics and configured to combine the first and second optical axes, while reflecting at least one of the first or second optical axis multiple times within the prism combiner.

2. The optical apparatus of claim 1 , wherein the condensing optics are configured to project the radiation uniformly over an area of the field having a diagonal dimension exceeding 2 mm, with an irradiance that varies by no more than 10% across the area and with a radiant intensity that varies across the numerical aperture by no more than 20% at all points in the area.

3. The optical apparatus of claim 2 , wherein the diagonal dimension of the area of the field over which the condensing optics project the optical radiation exceeds 15 mm.

4. The optical apparatus of claim 1 , wherein the extended radiation source comprises an array of emitters, and the apparatus comprises a radiation source controller, which is coupled to control the spatial distribution by selectively energizing the emitters by the radiation source controller.

5. The optical apparatus of claim 4 , wherein the array of emitters is a first array, and wherein the condensing optics comprise a second array of homogenizing rods, each of the homogenizing rods comprising an entrance face positioned to receive the emitted radiation from one or more of the emitters, and an exit face through which the radiation is emitted.

6. The optical apparatus of claim 5 , wherein the condensing optics comprise:
a third array of collimating lenses, wherein each collimating lens is configured to receive and collimate the radiation emitted from a respective one of the homogenizing rods; and
a focusing lens positioned to receive the collimated radiation from the third array of collimating lenses and to transmit and focus the radiation onto the field.

7. The optical apparatus of claim 6 , wherein the collimating lenses comprise Fresnel lenses or the focusing lens comprises a Fresnel lens.

8. The optical apparatus of claim 5 , wherein the exit face of each homogenizing rod comprises at least one of a field lens and a diffuser.

9. The optical apparatus of claim 4 , wherein the radiation source controller is configured to selectively energize the emitters so as to select an angular range of the radiation projected onto the field, wherein the angular range is selected from a group of angular ranges consisting of a dark field and a bright field illumination range.

10. The optical apparatus of claim 1 , wherein the prism combiner is configured to transmit the first optical axis and to reflect the second optical axis twice within the prism combiner.

11. The optical apparatus of claim 10 , wherein the second optical axis is reflected by total internal reflection from a surface of the prism combiner that is adjacent to the field.

12. The apparatus according to claim 1 , wherein the condensing optics comprise a compensating lens having a meniscus shape in proximity to the prism combiner.

13. The optical apparatus of claim 1 , wherein the prism combiner is configured to reflect the first optical axis multiple times within the prism combiner so as to homogenize the radiation projected onto the field.

14. The optical apparatus of claim 13 , wherein the first optical axis is reflected by total internal reflection from a surface of the prism combiner that faces the imaging assembly.

15. The optical apparatus of claim 13 , wherein the prism combiner has a rectangular cross section and comprises an entrance face in proximity to the condensing optics and an exit face in proximity to the field, and wherein the condensing optics are configured to focus the radiation emitted by the extended radiation source onto the entrance face.

16. The optical apparatus of claim 15 , wherein the extended radiation source comprises an array of emitters, and the condensing optics are configured to image each of the emitters onto the entrance face.

17. The optical apparatus of claim 16 , wherein the condensing optics comprise a Fresnel focusing lens.

18. The optical apparatus of claim 1 , wherein the extended radiation source comprises:
a radiation source; and
a spatial light modulator configured to receive and selectively transmit the radiation emitted by the radiation source, and
wherein the apparatus comprises a radiation source controller, which is coupled to control the spatial distribution by driving the spatial light modulator.

19. The optical apparatus of claim 18 , wherein the radiation source controller is configured to selectively control the spatial light modulator so as to select an angular range of the radiation projected onto the field.

20. The optical apparatus of claim 18 , wherein the spatial light modulator comprises a digital micromirror device.

21. The optical apparatus of claim 18 , wherein the spatial light modulator comprises a liquid crystal device.

22. The apparatus of claim 1 , wherein the prism combiner comprises:
an entrance face positioned to receive the radiation projected by the condensing optics along the first optical axis;
an exit face in proximity to the field; and
multiple beamsplitter layers within the prism combiner, wherein each of the multiple beamsplitter layers is configured to reflect a respective portion of the radiation through the exit face onto the field while transmitting the second optical axis.

23. The optical apparatus of claim 22 , wherein the prism combiner is configured to serve as a waveguide for the projected radiation.

24. The optical apparatus of claim 22 , wherein the prism combiner comprises a mirror that is parallel to the beamsplitter layers and is configured to receive the radiation entering through the entrance face and reflect the received radiation so as to cause the radiation to propagate within the prism combiner.

Assignees

• Orbotech Ltd

Inventors

• Fisch David
• Adler Avraham
• Lutsker Ilia
• Katzir Yigal
• Rosenberg Avinoam

Classifications

• G02B19/0066 Primary

  in the form of an LED array · CPC title

• G02B3/08

  with discontinuous faces, e.g. Fresnel lens {(diffractive Fresnel lenses G02B5/1876)} · CPC title

• G02B21/361

  Optical details, e.g. image relay to the camera or image sensor (G02B21/364 takes precedence; illumination details G02B21/06 and subgroups) · CPC title

• G02B26/0833

  the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B) · CPC title

• G02F1/29

  for the control of the position or the direction of light beams, i.e. deflection · CPC title