# US 11,079,515 B2 · Micro lens time-of-flight sensor having micro lens heights that vary based on image height

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- Number: US 11,079,515 B2
- Document ID: US11079515B2
- Status: Granted
- Kind: B2
- Application number: 16/719,968
- Filed: 2019-12-18
- Published: 2021-06-24
- Granted: 2021-08-03
- Earliest claimed: 2019-12-18
- Assignees: Microsoft Technology Licensing, LLC
- Applicants: Microsoft Technology Licensing, LLC
- Inventors: Zhanping Xu; Vei-Han Chan
- Web page: https://patentgrep.com/patent/US11079515B2

## CPC

- G02B 3/0043: {Inhomogeneous or irregular arrays, e.g. varying shape, size, height}
- H10F 39/806: {Optical elements or arrangements associated with the image sensors}
- G01B 11/24: for measuring contours or curvatures
- G01S 7/4816: {of receivers alone}
- G01S 7/4914: of detector arrays, e.g. charge-transfer gates
- G01S 7/4915: Time delay measurement, e.g. operational details for pixel components (signal extraction and conditioning G01S7/493); Phase measurement
- G01S 17/894: Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar
- G02B 3/0037: {characterized by the distribution or form of lenses}
- G02B 3/0056: {arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses (G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085)}
- H10F 39/8023: {Disposition of the elements in pixels, e.g. smaller elements in the centre of the imager compared to larger elements at the periphery}
- H10F 39/8063: {Microlenses}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A three-dimensional time-of-flight (3D TOF) camera having a micro lens (ML) array configured with variable ML height and variable ML shift. The ML array includes micro lens that are configured to direct backscattered light that is transmitted through an image lens into corresponding pixels. Heights of individual micro lenses within the ML array vary according to image height. For example, the height of micro lenses at the center of the ML array, near the axis of the image lens, may be relatively larger than the height of other micro lenses toward the perimeter of the ML array. Furthermore, the shift of individual micro lenses with respect to corresponding pixels may also vary according to the image height. For example, the shift of micro lenses at the center of the ML array may be relatively smaller than the shift of the other micro lenses toward the perimeter of the ML array.

## Claims

### Claim 1

A three-dimensional time-of-flight image camera, comprising:
a signal generator configured to generate a modulated electrical signal;
a light emitter configured to emit modulated light in accordance with the modulated electrical signal;
an image lens configured to receive backscattered light that includes at least a portion of the modulated light;
a pixel array that includes a plurality of pixels that are configured to generate photoelectric signals in response to the portion of the modulated light; and
a micro lens array that includes a plurality of micro lenses having a plurality of different micro lens heights, wherein individual micro lenses are configured with individual micro lens heights that are inversely related to image heights of the individual micro lenses with respect to an axis of the image lens.

### Claim 2 (depends on 1)

The three-dimensional time-of-flight image camera of claim 1, wherein the micro lens heights are linearly proportional to the image heights of the individual micro lenses with respect to an axis of the image lens.

### Claim 3 (depends on 1)

The three-dimensional time-of-flight image camera of claim 1, wherein the micro lens heights are non-linearly related to the image heights of the individual micro lenses with respect to an axis of the image lens.

### Claim 4 (depends on 1)

The three-dimensional time-of-flight image camera of claim 1, wherein the individual micro lenses are further configured with individual micro lens shifts, with respect to corresponding individual pixels, that are directly related to the image heights of the individual micro lenses with respect to the axis of the image lens.

### Claim 5 (depends on 4)

The three-dimensional time-of-flight image camera of claim 4, wherein the individual micro lens shifts are non-linearly related to the image heights of the individual micro lenses with respect to an axis of the image lens.

### Claim 6 (depends on 4)

The three-dimensional time-of-flight image camera of claim 4, wherein the individual micro lens shifts correspond to maximized volumetric photon hit rates for individual bundles of input rays that are bound between upper rim rays and lower rim rays extending from the image lens to the individual micro lenses.

### Claim 7 (depends on 1)

The three-dimensional time-of-flight image camera of claim 1, wherein the plurality of micro lenses includes at least:
a first micro lens to direct the portion of the modulated light into a first region of interest of a first pixel at a first image height with respect to the axis of the image lens, wherein the first micro lens has a first micro lens shift with respect to the first pixel and a first micro lens height; and
a second micro lens to direct the portion of the modulated light into a second region of interest of a second pixel at a second image height with respect to the axis of the image lens, wherein the second micro lens has a second micro lens shift with respect to the second pixel and a second micro lens height, wherein the first micro lens height is greater than the second micro lens height and the first micro lens shift is less than the second micro lens shift based on the first image height being less than the second image height.

### Claim 8 (depends on 1)

The three-dimensional time-of-flight image camera of claim 1, further comprising a controller configured to generate depth data based at least in part on demodulation of the modulated electrical signal from the photoelectric signals that result from the portion of the modulated light being directed through the plurality of micro lenses having the plurality of different micro lens heights that are inversely related to the image heights of the individual micro lenses.

### Claim 9

A time-of-flight camera, comprising:
a light emitter to illuminate a physical object with modulated light that is emitted in accordance with a modulated electrical signal;
an image lens configured to transmit backscattered light that is reflected by the physical object, the backscattered light including a reflected portion of the modulated light; and
a micro lens time-of-flight (ML-TOF) sensor to generate photoelectric signals in response to the backscattered light that is transmitted through the image lens, the ML-TOF sensor including:
a plurality of pixels that are configured to generate the photoelectric signals, and
a plurality of micro lenses that are configured to focus the backscattered light into regions of interest of the plurality of pixels, the plurality of micro lenses configured with micro lens heights and micro lens shifts that vary based on image heights with respect to an axis of the image lens.

### Claim 10 (depends on 9)

The time-of-flight camera of claim 9, wherein the micro lens heights are inversely related to the image heights.

### Claim 11 (depends on 10)

The time-of-flight camera of claim 10, wherein the micro lens shifts are directly related to the image heights.

### Claim 12 (depends on 11)

The time-of-flight camera of claim 11, wherein both of the micro lens heights and the micro lens shifts are non-linearly related to the image heights.

### Claim 13 (depends on 9)

The time-of-flight camera of claim 9, wherein individual amounts for the micro lens shifts correspond to maximized volumetric photon hit rates for individual bundles of input rays that are bound between upper rim rays and lower rim rays extending from the image lens to individual ones of the plurality of micro lenses.

### Claim 14 (depends on 9)

The time-of-flight camera of claim 9, wherein the plurality of micro lenses are further configured with spherical curvature radiuses that vary based on image heights with respect to an axis of the image lens.

### Claim 15 (depends on 9)

The time-of-flight camera of claim 9, further comprising a controller configured to generate depth data based at least in part on demodulation of the modulated electrical signal from the photoelectric signals.