Systems and methods for beam steering using a micromirror device
AssigneeArizona Board of Regents on Behalf of the University of Arizona
InventorsYuzuru Takashima, Braden Smith, Brandon Hellman
Life of this patent
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Abstract
A beam steering apparatus including a first actuatable micromirror array (AMA) having a pitch, p, adapted to impart a modulation to a wavefront incident on the first AMA by a transition between a first state and a second state, wherein the first AMA has a transition time (T) between the first state and the second state, and at least one light source adapted to provide the incident wavefront having a duration, t, to the first AMA, where t≤T. The AMA may be a MEMS device such as a digital micromirror array. The beam steering apparatus may constitute a portion of LIDAR system.
Claims17
A beam steering apparatus, comprising:
- a first actuatable micromirror array (AMA) having a pitch, p, adapted to impart a modulation to a wavefront incident on the first AMA by a transition between a first state and a second state, wherein the first AMA has a transition time (T) between the first state and the second state;
- and
- at least one light source adapted to provide the incident wavefront having a duration, tmax, to the first AMA,
- where tmax≤T;
- wherein
- tmax≤T/NMax,
- where NMax is the number of diffraction orders of the incident wavefront supported by the AMA, and is given by,
- N
- max
- =
- 1
- +
- floor
-
-
- p
-
- [
- sin
-
- (
- 2
-
- α
- -
- β
- )
- +
- sin
-
-
- (
- β
- )
- ]
- 2
-
- λ
-
- +
- floor
-
-
- p
-
- [
- sin
-
- (
- -
- 2
-
- α
- -
- β
- )
- +
- sin
-
-
- (
- β
- )
- ]
- 2
-
- λ
-
- where 2α is the phase tilt angle induced by the first AMA for a normal incident wavefront, β is the in-plane angle of incidence of the incident wavefront along which phase is modulated, λ is the wavelength of light from the at least one light source, and the function ‘floor’ rounds NMax down to the nearest integer,
- further wherein the first AMA functions as a blazed grating according to the equation
- θ
- m
- =
- arcsin
-
- (
- 2
-
- m
-
-
- λ
- p
- -
- sin
-
-
- (
- β
- )
- )
- +
- β
- ,
- where θm is a diffraction angle supported by said blazed grating, and m is the diffraction order.
A method for making an effective blazed grating, comprising:
- actuating an actuatable micromirror array (AMA) array between a first state and a second state, wherein the AMA has a transition time, T between the first state and the second state;
- and
- directing a wavefront onto the AMA, the wavefront having a duration t,
- where tmax≤T, wherein
- where tmax≤T, wherein
- where NMax is the number of diffraction orders with diffraction efficiency equal to or greater than 50% of the incident wavefront supported by the AMA,
- wherein the AMA functions as a blazed grating according to the equation
- θ
- m
- =
- arcsin
-
- (
- 2
-
- m
-
-
- λ
- p
- -
- sin
-
-
- (
- β
- )
- )
- +
- β
- ,
- where θm is the diffraction angle(s) supported by said blazed grating, λ is the wavelength of the incident wavefront, and m is the diffraction order, β is in-plane angle of incidence of incident wavefront along which phase is modulated.
A LIDAR system for detecting an object, comprising:
- a first actuatable micromirror array (AMA) having a pitch, p, adapted to impart a modulation to a wavefront incident on the first AMA by a transition between a first state and a second state, wherein the first AMA has a transition time (T) between the first state and the second state;
- at least one light source adapted to provide the incident wavefront having a maximum duration, tmax, to the first AMA, where tmax≤T;
- and
- a detector positioned to receive light from the wavefront after it is directed onto the object,
- wherein
- tmax≤T/NMax,
- where NMax is the number of diffraction orders of the incident wavefront supported by the AMA, and is given by,
- N
- max
- =
- 1
- +
- floor
-
- ❘
- "\[LeftBracketingBar]"
- p
- [
- sin
-
- (
- 2
-
- α
- -
- β
- )
- +
- sin
-
- (
- β
- )
- ]
- 2
-
- λ
- ❘
- "\[RightBracketingBar]"
- +
- floor
-
- ❘
- "\[LeftBracketingBar]"
- p
- [
- sin
-
- (
- -
- 2
-
- α
- -
- β
- )
- +
- sin
-
- (
- β
- )
- ]
- 2
-
- λ
- ❘
- "\[RightBracketingBar]"
- where 2α is the phase tilt angle induced by the first AMA for a normal incident wavefront, β is the in-plane angle of incidence of the incident wavefront along which phase is modulated, λ is the wavelength of light from the at least one light source, and the function ‘floor’ rounds NMax down to the nearest integer,
- further wherein the first AMA functions as a blazed grating according to the equation
- θ
- m
- =
- arc
-
- sin
-
- (
- 2
-
- m
-
- λ
- p
- -
- sin
-
- (
- β
- )
- )
- +
- β
- ,
- where θm is a diffraction angle supported by said blazed grating, and m is the diffraction order.
Dependencies are inferred from the claim text.