Apparatus and method for measuring surface topography optically
First Claim
1. An apparatus for determining surface topography of a structure, the apparatus comprising:
- a probe;
an illumination unit configured to output a plurality of light beams;
a light focusing assembly comprising an image space lens and an object space lens;
a focus changing assembly located along an optical path between the image space lens and the object space lens, a portion of the focus changing assembly located at a back focal length of the object space lens and comprising a variable optical power element or a divergent and a convergent lens;
a detector having an array of sensing elements configured to measure a characteristic of each of a plurality of light beams returning from the illuminated spots; and
a processor coupled to the detector and configured to generate data representative of topography of the structure based on the measured characteristic of each of the plurality of light beams returning from the illuminated spots,wherein the light focusing assembly is configured to;
receive each of the plurality of light beams;
overlap the plurality of light beams within a focus changing assembly; and
focus each of the plurality of light beams to a respective focal point external to the probe in order to generate illuminated spots on the structure, andwherein the focus changing assembly is configured to move the respective focal points along a direction of propagation of the plurality of light beams.
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Abstract
An apparatus is described for determining surface topography of a three-dimensional structure. The apparatus can include a probe and an illumination unit configured to output a plurality of light beams. In many embodiments, the apparatus includes a light focusing assembly. The light focusing assembly can receive and focus each of a plurality of light beams to a respective external focal point. The light focusing assembly can be configured to overlap the plurality of light beams within a focus changing assembly in order to move the external focal points along a direction of propagation of the light beams. The apparatus can include a detector having an array of sensing elements configured to measure a characteristic of each of a plurality of light beams returning from the illuminated spots and a processor coupled to the detector and configured to generate data representative of topography of the structure based on the measured characteristic.
232 Citations
20 Claims
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1. An apparatus for determining surface topography of a structure, the apparatus comprising:
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a probe; an illumination unit configured to output a plurality of light beams; a light focusing assembly comprising an image space lens and an object space lens; a focus changing assembly located along an optical path between the image space lens and the object space lens, a portion of the focus changing assembly located at a back focal length of the object space lens and comprising a variable optical power element or a divergent and a convergent lens; a detector having an array of sensing elements configured to measure a characteristic of each of a plurality of light beams returning from the illuminated spots; and a processor coupled to the detector and configured to generate data representative of topography of the structure based on the measured characteristic of each of the plurality of light beams returning from the illuminated spots, wherein the light focusing assembly is configured to; receive each of the plurality of light beams; overlap the plurality of light beams within a focus changing assembly; and focus each of the plurality of light beams to a respective focal point external to the probe in order to generate illuminated spots on the structure, and wherein the focus changing assembly is configured to move the respective focal points along a direction of propagation of the plurality of light beams. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of determining surface topography of a structure, the method comprising:
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generating illuminated spots on the structure using a light focusing assembly including an image space lens and an object space lens to receive and focus each of a plurality of light beams to a respective focal point external to a probe; operating the light focusing assembly to overlap each of the plurality of light beams within a focus changing assembly located along an optical path between the image space lens and the object space lens, a portion of the focus changing assembly located at a back focal length of the object space lens and comprising a variable optical power element or a divergent and a convergent lens; operating the focus changing assembly to displace the respective focal points along a direction of propagation of the plurality of light beams; measuring a characteristic of each of a plurality of light beams returning from the illuminated spots; and generating, with a processor, data representative of topography of the structure based on the measured characteristic. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification