Multispectral LiDAR comprising a spectral delay unit
A multispectral laser detection and ranging device including a spectral delay unit configured for delaying the broadband laser beam pulse depending on the wavelength, to give a wavelength comb selected in the spectral range, such that the broadband laser beam pulse is transformed into a pulse-train wherein each pulse in the train is at a different wavelength of the wavelength comb.
1 . A multispectral laser detection and ranging device, the device comprising,
an optical input for receiving a broadband laser beam pulse having a spectral range,
an optical transmitter configured for outputting the broadband laser beam pulse along a direction, the optical input and the optical transmitter being optically connected, and
an optical receiver configured to receive a reflection of the broadband laser beam pulse from said direction, and
an optical detector configured to detect a time-of-flight and an optical power of at least part of the reflection of the broadband laser beam pulse, wherein the optical detector is optically connected to the optical receiver, wherein the device further comprises:
-a spectral delay unit configured for delaying the broadband laser beam pulse depending on the wavelength, to give a wavelength comb selected in the spectral range, such that the broadband laser beam pulse is transformed into a pulse-train wherein each pulse in the train is at a different wavelength of the wavelength comb,
wherein the spectral delay unit comprises an optical fiber,
wherein the spectral delay unit comprises a delay input configured to receive the broadband laser beam pulse, and further comprises a delay output configured to transmit the pulse-train, wherein the delay input and the delay output are both a same end of said optical fiber of the spectral delay unit,
wherein the device further comprises an optical circulator,
wherein said optical circulator comprises a first port, a second port and a third port, and is configured such that light inputted in the first port is outputted from the second port, and light inputted in the second port is outputted from the third port,
wherein said same end of the optical fiber is optically connected to the second port of the optical circulator,
wherein the first port is fiber-coupled with the optical input, and the third port is fiber-coupled with a scanning module, wherein the scanning module comprises the optical transmitter,
wherein the scanning module further comprises the optical receiver, and
wherein the optical circulator further comprises a fourth port, configured such that light inputted in the third port is outputted from the fourth port, wherein the fourth port is fiber-coupled with the optical detector.
2 . The device according to claim 1 , wherein the optical detector is a broadband unique detector.
3 . The device according to claim 1 , wherein a pulse within the pulse train has a filtered bandwidth which is the bandwidth of the spectral range of the broadband laser beam pulse divided by 4 or 5.
4 . The device according to claim 1 , wherein the optical detector is an avalanche photodiode electrically connected to a digitizer having a sample rate of 3 GS/s, and to Field Programmable Gate Arrays.
5 . The device according to claim 1 , wherein the optical fiber is grated with a fiber Bragg grating.
6 . The device according to claim 5 , wherein the optical fiber Bragg grating is a superstructured Fiber Bragg Grating comprising a plurality of successive fiber Bragg gratings, wherein the gratings are configured to reflect the wavelength comb part of the broadband laser beam pulse, wherein the length between two adjacent fiber Bragg gratings is selected as a function of a time interval between two adjacent pulses in the train pulses.
7 . The device according to claim 1 , further comprising a broadband laser source connected to the optical input and configured to send the broadband laser beam pulses to the optical input.
8 . The device according to claim 7 , wherein the laser source is a supercontinuum laser source.
9 . The device according to claim 8 , wherein the broadband laser beam pulse has a spectral range comprised between 1000 nm and 1700 nm.
10 . The device according to claim 8 , wherein each of the broadband laser beam pulse has a pulse duration comprised between 0.5 ns and 5 ns.
11 . The device according to claim 10 , wherein the pulse duration is about 1 ns.
12 . The device according to claim 8 , wherein each of the broadband laser beam pulse exhibits a bandwidth comprised between 200 nm and 300 nm.
13 . The device according to claim 8 , wherein each of the laser beam pulse exhibits a bandwidth of 300 nm and the broadband laser beam pulse has a spectral range comprised between 1400-1700 nm, which is an optimum configuration for eye-safety and low-cost detection.
14 . A vehicle comprising a device according to claim 1 .
15 . A multispectral laser detection and ranging device, the device comprising,
an optical input for receiving a broadband laser beam pulse having a spectral range,
an optical transmitter configured for outputting the broadband laser beam pulse along a direction, the optical input and the optical transmitter being optically connected, and
an optical receiver configured to receive a reflection of the broadband laser beam pulse from said direction, and
an optical detector configured to detect a time-of-flight and an optical power of at least part of the reflection of the broadband laser beam pulse, wherein the optical detector is optically connected to the optical receiver, wherein the device further comprises:
a spectral delay unit configured for delaying the broadband laser beam pulse depending on the wavelength, to give a wavelength comb selected in the spectral range, such that the broadband laser beam pulse is transformed into a pulse-train wherein each pulse in the train is at a different wavelength of the wavelength comb,
wherein the spectral delay unit comprises an optical fiber,
wherein the spectral delay unit comprises a delay input configured to receive the broadband laser beam pulse, and further comprises a delay output configured to transmit the pulse-train, wherein the delay input and the delay output are both a same end of said optical fiber of the spectral delay unit,
wherein the device further comprises an optical circulator,
wherein said optical circulator comprises a first port, a second port, a third port and a fourth port, and is configured such that light inputted in the first port is outputted from the second port, and light inputted in the second port is outputted from the third port, and configured such that light inputted in the third port is outputted from the fourth port,
wherein said same end of the optical fiber is optically connected to the third port of the optical circulator,
wherein the first port is fiber-coupled with the optical input, and the third port is fiber-coupled with a scanning module, wherein the scanning module comprises the optical transmitter,
wherein the scanning module further comprises the optical receiver, and wherein the fourth port is fiber-coupled with the optical detector.
16 . The device according to claim 15 , wherein the optical detector is a broadband unique detector.
17 . The device according to claim 15 , wherein a pulse within the pulse train has a filtered bandwidth which is the bandwidth of the spectral range of the broadband laser beam pulse divided by 4 or 5.
18 . The device according to claim 15 , further comprising a broadband laser source connected to the optical input and configured to send the broadband laser beam pulses to the optical input.
19 . The device according to claim 18 , wherein the laser source is a supercontinuum laser source.
20 . The device according to claim 15 , wherein each of the broadband laser beam pulse exhibits a bandwidth comprised between 200 nm and 300 nm.