System and method for active hyperspectral imaging with supercontinuum light
An imaging system includes an imager having first and second light sensors, the first light sensor being configured to record light in a first wavelength range and the second light sensor being configured to record light in a second wavelength range, an alignment mechanism configured to be attached to the imager, an illumination source configured to generate a supercontinuum light beam, and a light shaping mechanism configured to transform the supercontinuum light beam into a linear strip of light. The alignment mechanism is configured to adjust a position of the light shaping mechanism so that a back scattered light, resulting from a scattering of the linear strip of light from a target, has an intensity above a given minimum for each of the first and second light sensors.
1 . An imaging system comprising:
an imager having first and second light sensors, the first light sensor being configured to record light in a first wavelength range and the second light sensor being configured to record light in a second wavelength range, different from the first wavelength range;
an alignment mechanism configured to be attached to the imager;
an illumination source configured to generate a supercontinuum light beam; and
a light shaping mechanism configured to transform the supercontinuum light beam into a linear strip of light, the light shaping mechanism being attached to the alignment mechanism,
wherein the alignment mechanism is configured to adjust a position of the light shaping mechanism so that a back scattered light, resulting from a scattering of the linear strip of light from a target, has an intensity above a given minimum for each of the first and second light sensors.
2 . The imaging system of claim 1 , wherein the light shaping mechanism is attached to a collimator sleeve, which holds a collimator.
3 . The imaging system of claim 2 , wherein the collimator sleeve is configured to collimate the supercontinuum light beam before entering the light shaping mechanism, and alignment mechanism is configured to move in unison the collimator sleeve, the collimator, and the light shaping mechanism move relative to the imager.
4 . The imaging system of claim 1 , wherein the alignment mechanism comprises:
a first alignment device attached to a first horizontal rail of the alignment mechanism, the first alignment device being attached to a support track; and
a second alignment device attached to a second horizontal rail of the alignment mechanism, the second alignment device being attached to the support track.
5 . The imaging device of claim 4 , wherein the first alignment device includes a motor and wheels to horizontally move along the first horizontal rail, and the second alignment device includes a motor and wheels to horizontally move along the second horizontal rail.
6 . The imaging device of claim 5 , wherein the second rail has end wheels to vertically move along side rails of the alignment mechanism.
7 . The imaging device of claim 5 , wherein the alignment mechanism further comprises:
a collimator sleeve rotatably attached to the support track, wherein the light shaping mechanism is attached to one end of the collimator sleeve;
a collimator provided inside the collimator sleeve; and
a rotational mechanism configured to rotate with a belt the collimator sleeve relative to the support track.
8 . The imaging device of claim 1 , further comprising:
a housing configured to house the imager, the alignment mechanism, the illumination source, and the light shaping mechanism; and
a rotating mechanism externally attached to the housing and configured to rotate the housing about a vertical axis.
9 . The imaging device of claim 8 , further comprising:
a global controller configured to control the imager, the alignment mechanism, the illumination source, and the rotating mechanism so that, as the rotating mechanism rotates the enclosure to build up an image of the target, the alignment mechanism maintains a light intensity of the back scattered light above corresponding minima for the first and second light sensors, by adjusting the position of the light shaping mechanism relative to the imager.
10 . The imaging device of claim 1 , wherein the imager is an active hyperspectral camera, the illumination source includes a supercontinuum laser, and the light shaping mechanism includes a Powell lens.
11 . The imaging device of claim 1 , wherein the first wavelength range is about 400 to 1000 nm and the second wavelength range is about 970 to 2500 nm.
12 . The imaging system of claim 1 , wherein the first light sensor includes an array of sensors distributed in a line and the first light sensor is configured to simultaneously record the back scattered light from a line of pixels while the second light sensor includes a sensor that records the back scattered light from a pixel of the target.
13 . An alignment mechanism for an active hyperspectral imaging system that uses a supercontinuum laser, the alignment mechanism comprising:
a frame;
a first horizontal rail attached to the frame;
a second horizontal rail attached to the frame;
a first alignment device movably attached to the first horizontal rail;
a second alignment device movably attached to the second horizontal rail;
a support track attached with a first end to the first alignment device and with a second end to the second alignment device;
a collimator sleeve rotatably attached to the support track and configured to receive a collimator and a light shaping mechanism; and
a rotational mechanism configured to rotate the collimator sleeve relative to the support track,
wherein the first alignment device is configured to move independent of the second alignment device, and
wherein the alignment mechanism is portable.
14 . The alignment mechanism of claim 13 , wherein the first alignment device includes a motor and wheels to horizontally move along the first horizontal rail, and the second alignment device includes a motor and wheels to horizontally move along the second horizontal rail.
15 . The alignment mechanism of claim 14 , wherein the second horizontal rail has end wheels to vertically move along side rails of the frame while the first horizontal rail is fixedly attached to the frame.
16 . The alignment mechanism of claim 14 , wherein the rotational mechanism comprises:
a motor; and
a belt,
wherein the belt is configured to round the collimator sleeve and to rotate the collimator sleeve when engaged by the motor.
17 . The alignment mechanism of claim 13 , wherein the collimator sleeve has end ball bearings for rotating relative to the support track, and a pulley located on the outside of the collimator sleeve, to engage a belt of the rotational mechanism.
18 . The alignment mechanism of claim 13 , wherein the rotational mechanism is directly attached to the support track.
19 . A method for aligning an emitted light of an illumination source with a back scattered light received from a target, the method comprising:
generating a supercontinuum light beam with a supercontinuum laser;
transforming the supercontinuum light beam into a linear strip of light with a Powell lens and projecting the linear strip of light onto the target;
recording, with an imager, back scattered light from the target, which is a reflection or transmission of the linear strip of light on the target, wherein the imager rotates to scan the entire target;
adjusting a position of the Powell lens with an alignment mechanism so that a highest light intensity of the back scattered light is recorded by the imager as the imager rotates; and
identifying a material composition of the target based on a spectral signature obtained from the recorded back scattered light.
20 . The method of claim 19 , wherein the spectral signature is generated line by line or pixel by pixel for the target.