KR102500054B1 - Systems and methods for underwater illumination, survey, and wireless optical communications - Google Patents

Abstract

Embodiments of the present invention disclose an underwater optical communication and illumination system using blue light laser diodes that are directly encoded with spectral efficient Quadrature Amplitude Modulation-Quadrature Frequency Division Multiplexing (QAM-OFDM) data. A broadband light source may be used to provide illumination for both underwater regions of interest and underwater optical communications remote from the region of interest.

Description

Systems and methods for underwater lighting, irradiation, and wireless optical communication

An embodiment of the present disclosure discloses an underwater optical communication and lighting system.

Underwater human activities such as oceanography research, offshore oil exploration, seabed surveying and environmental monitoring are increasing considerably. As a result, there is a growing need for reliable lighting and high-speed underwater wireless communication (UWOC) systems. Traditionally, visible light sources have not been associated with underwater communication systems. Various lighting devices are known including, for example, incandescent light sources and LED light sources. Acoustic communication systems are also well known. However, the bandwidth of underwater acoustic channels is limited to hundreds of kHz due to the strong frequency dependent attenuation of sound in seawater. The slow propagation of sound waves causes large time delays in acoustic communication systems. Additionally, radio frequency (RF) communications are severely limited due to the conductivity of ocean water at radio frequencies.

Embodiments of the present disclosure disclose an underwater optical communication and illumination system using blue light laser diodes encoded directly with spectral efficient Quadrature Amplitude Modulation-Quadrature Frequency Division Multiplexing (QAM-OFDM) data.

Optical-based UWOC systems are attracting interest from military and academic research groups and have been proposed as alternative or complementary solutions to acoustic and RF underwater communication links at short to medium distances (less than 100 m). Technological advances in visible light emitters, receivers, digital communications and signal processing currently take advantage of the low absorption of seawater in the cyan (400-550 nm) region of the visible light window of the electromagnetic spectrum. The purpose of optical-based UWOC systems is to provide high data rates to transmit large amounts of data for multi-purpose applications such as underwater oil pipe inspection, remotely operated vehicle (ROV) and sensor networks.

The underwater propagation of light is governed by attenuation, a combined effect of absorption and scattering mechanisms. Since the aquatic environment is very optically challenging, the effect of multiple scattering, especially in turbid coastal waters, can degrade the bit error rate (BER) performance of high-speed UWOC systems based on on-off keying (OOK). greatly decrease

In general, embodiments of the present invention disclose underwater vision (illumination) and wireless optical communication systems using GaN-based light sources for data rates of gigabits per second over long distances (5 to 20 meters and beyond). In some embodiments, the broadband light consists of multiple wavelengths of lasers for white light illumination and communication. In another embodiment of the present invention, a UWOC system using a purple or blue laser coupled with a phosphor material in a transmit module to generate white light may be used for both underwater vision and communications. Phosphor materials used for generating white light refer to a kind of color conversion material that can produce blue, green, yellow or red when excited by a purple or blue laser. By mixing these colors, white light having various color rendering indices and color temperatures can be obtained.

Embodiments of the present invention disclose low light detection methods for long-distance underwater communication as well as various spectral efficient techniques such as orthogonal frequency division multiplexing and spectrum multiplexing including frequency division multiplexing.

Embodiments of the present invention provide point-to-point underwater data communication and also separate optics to illuminate the underwater environment by providing visible light useful for conducting underwater exploration or other activities, for example. Includes light sources used with optics.

The details of one or more embodiments are set forth in the description below. Other features, objects and advantages will be apparent from the description below and from the claims.

Optical-based UWOC systems are attracting interest from military and academic research groups and have been proposed as alternative or complementary solutions to acoustic and RF underwater communication links at short to medium distances (less than 100 m). Technological advances in visible light emitters, receivers, digital communications and signal processing currently take advantage of the low absorption of seawater in the cyan (400-550 nm) region of the visible light window of the electromagnetic spectrum. The purpose of optical-based UWOC systems is to provide high data rates to transmit large amounts of data for multi-purpose applications such as underwater oil pipe inspection, remotely operated vehicle (ROV) and sensor networks.

This written disclosure describes exemplary, non-limiting and non-exhaustive embodiments. In the drawings, which are not necessarily drawn to scale, like reference numbers throughout the views indicate substantially similar elements. Like reference numbers with different letter suffixes indicate various instances of substantially similar elements. The drawings generally describe the various embodiments discussed herein by way of example and not as limitations.
An exemplary embodiment shown in the drawings is described, in which:
1 shows a schematic diagram of a laser diode (LD) based UWOC system in accordance with one or more embodiments of the present invention.
FIG. 2 shows a conceptual block diagram of a 16-QAM-OFDM data generation and underwater transmission system suitable for use with the embodiment of FIG. 1 .
3 is a table summarizing the relevant parameters of a 16-QAM-OFDM data stream carried by a TO-9 package blue LD including symbol length, subcarrier frequency and subcarrier frequency spacing under various transmission data rates.
Figure 4 shows the behavior of 16-QAM-OFDM data encoded directly onto a TO-9 package blue LD after offset by DC bias current.
5(a) shows a graph of light-current-voltage (LIV) characteristics of a TO-9 package LD.
Figure 5(b) shows a graph of lasing spectra versus wavelength at 250 C under various bias currents.
6 shows the small-signal modulation response of a blue laser diode at various bias currents.
Figure 7(a) shows a graph of measured BER versus laser bias current.
Figure 7(b) shows a graph of a constellation diagram at 70 mA.
Figure 8(a) shows a graph of measured BER versus modulation bandwidth of 16-QAM-OFDM data.
8B shows a graph of the measured electrical signal-to-noise ratio (SNR) of received 16-QAM-OFDM data as a function of subcarrier index.
8(c) shows a graph of a constellation of a 1.2 GHz 16-QAM-OFDM signal transmitted through a 5.4 m underwater channel.
9 shows a graph of measured BER versus link distance for a 1.2 GHz 16-QAM-OFDM signal.
10 illustrates a compact integrated underwater lighting, irradiation and optical communication system in accordance with one or more embodiments of the present invention.

The present invention relates to a laser diode based underwater lighting and wireless optical communication (LD-UWOC) system. In one embodiment, the LD-UWOC system is based on a simple non-return-to-zero on-off-keying (NRZ-OOK) modulation scheme over a 20-meter underwater channel for 1.5 Provides a data rate of Gbps. In another embodiment, a 16-quadrature amplitude modulation-orthogonal frequency division multiplexed (QAM-OFDM) based LD-UWOC system provides a data rate of 4.8 Gbit/s at a transmission distance of 5.4 m. do. For the NRZ-OOK based LD-UWOC system, the high-speed UWOC link provided a data rate of up to 2 Gbps over a distance of 12 meters and a data rate of 1.5 Gbps over a recorded 20-meter underwater channel. The measured bit error rates (BER) are 2.8×10 ^-5 and 3.0×10 ^-3 , respectively, which meet the forward error correction (FEC) criterion. For the 16 ^{-QAM-OFDM based LD-UWOC system, error vector magnitude (EVM) and signal-to-noise ratio (SNR) of 16.5% and 15.63 dB, respectively, were measured, and the corresponding BER was 2.6×10 -3 .} . Experimental results also show that scattering has minimal effect on the BER performance of a 1.2 GHz 16-QAM-OFDM signal transmitted over a link distance of up to 5.4 m in clear water. Thus, longer underwater transmissions are possible simply by increasing the power of the laser diode.

In an embodiment of the present invention, a blue light laser diode is used as an illumination source and a silicon (Si) avalanche photodiode is used with a separate optical system without the need for a diffuser. Cost-effective modulation techniques, i.e., non-return-to-zero on-off-keying (NRZ-OOK) modulation, and spectrally efficient modulation techniques, i.e., high-speed point-to-point in water Data was encoded using orthogonal frequency division multiplexed quadrature amplitude modulation (QAM-OFDM) for data communication.

Orthogonal frequency division multiplexing (OFDM) is a method of encoding digital data on multiple carrier frequencies. OFDM is a frequency division multiplexing scheme used as a digital multicarrier modulation scheme. A large number of closely spaced orthogonal subcarrier signals are used to transmit data in multiple parallel data streams or channels. Each subcarrier is modulated with a conventional modulation scheme (e.g. quadrature amplitude modulation or phase shift modulation) at a low symbol rate to maintain an aggregate data rate similar to conventional single carrier modulation schemes at the same bandwidth. .

Embodiments of the present invention are directed to underwater lighting and radio based direct modulation of GaN-based laser diodes (LDs) using on-off keying (OOK) or other spectrally efficient modulation techniques such as orthogonal frequency division multiplexing (OFDM) techniques. An optical communication system is further disclosed. Embodiments also disclose converged (point-to-point) high-speed communication links.

In an embodiment of the present invention, a GaN-based violet-blue laser diode (LD) is used as a high-power light source and high-speed underwater data communication. By combining phosphors in the UWOC system, white light can be generated, which simultaneously serves as a light source for vision applications.

1 is one inventive aspect of a laser diode (LD) based UWOC system using a 450 nm laser diode (10) in a transmit module (12) and a silicon (Si) avalanche photodiode (14) in a receive module (16). It is a schematic diagram of the above embodiment. The data stream is amplified by amplifier 18 before combining a bias-tee with the DC bias provided by DC power supply 22 driving laser diode 10 (Thorlabs LP450-SF15, 137 Output of 15 mW biasing in mA). A pair of plano-convex lenses 24, 26 are used in both the transmit module 12 and the receive module 16. Lenses 24 and 26 (Thorlabs LA1951-a) have a diameter of 25.4 mm and a focal length of 25.4 mm to produce a collimated free space beam. The laser beam passes through an underwater channel (30) and a photodetector (14) with an active diameter of 0.5 mm, a responsivity of 5 A/W at 450 nm and a noise equivalent power (NEP) of 0.4 pW/Hz ^½ . ) (Menlo Systems APD210).

One embodiment of the present invention discloses a high-speed UWOC link that provides data rates of up to 2 Gbps over a 12 meter length, with 1.5 Gbps achieved over a recorded 20 meter long underwater channel. To demonstrate the UWOC system based on the OOK modulation scheme, a pattern generator was used to generate a pseudo random binary sequence (PRBS) 2 ^10-1 data stream within the transmission module 12, The data stream is amplified by a 28 dB driver amplifier before being coupled to a 15 GHz wideband bias tee. The bit error rates (BER) for the UWOC system at 2 Gbps through a 9 m underwater channel, 2 Gbps through a 12 m underwater channel, and 1.5 Gbps through a 20 m underwater channel are 1.2×10 ⁻⁶ and 2.8×, respectively. 10 ⁻⁵ , and 3.0×10 ⁻³ , all of which pass the forward error correction (FEC) limit. Open eye diagrams and measured FEC-compliant BER for data rates up to 2 Gbps have been successfully achieved for 9-meter as well as 12-meter UWOC links.

Another embodiment of the present invention discloses underwater wireless optical transmission at 4.8 Gbit/s over a 5.4 m link using a highly spectrally efficient 16-QAM-OFDM modulation scheme. To test an underwater wireless optical transmission system using a highly spectrally efficient 16-QAM-OFDM modulation scheme, an arbitrary waveform generator (AWG) was used for signal generation and a digital serial signal generator was used to analyze the received signal. A digital serial analyzer (DSA) was used. A 16-QAM-OFDM signal with corresponding subcarriers was generated by an offline MATLAB program and sampled by an arbitrary waveform generator at a sampling rate of 24 GSa/s.

A conceptual block diagram of a 16-QAM-OFDM data generation and underwater transmission system is shown in FIG. The binary bitstream 40 is divided into parallel low-speed data blocks via serial-parallel module 42 and mapped to QAM symbols via symbol mapping module 44. An inverse fast Fourier transform (IFFT) module 46 converts the QAM symbols to a transient OFDM signal with a FET size of 512 and provides the parallel signal to parallel-serial module 48. In order to mitigate inter-symbol interference (ISI) in a transmission link, a cyclic prefix (CP) of 1/32 is added through the cyclic prefix module 50. 3 is a table summarizing the relevant parameters of a 16-QAM-OFDM data stream carried by a TO-9 package blue LD including symbol length, subcarrier frequency and subcarrier frequency spacing under various transmission data rates.

After digital-to-analog conversion (DAC) in module 52, the QAM-OFDM signal is electrically pre-amplified and directly encoded into the TO-9 package blue LD. In one embodiment, the QAM-OFDM signal was pre-amplified with a 26-dB wideband amplifier (Picosecond Pulse Labs, 5865) and then superimposed onto the DC bias current using the RF connector of the built-in bias tee in the diode mount (Thorlabs LDM9LP). , which directly encodes the TO-9 package blue LD. The DC bias point of the TO-9 package blue LD was optimized to achieve the largest peak-to-average power ratio (PAPR) of the modulated QAM-OFDM data stream. Electrical-to-optical domain conversion was performed according to the power versus current response of the blue LED, and optical 16-QAM-OFDM data with its maximum/minimum power levels determined by the maximum/minimum current levels. stream was created. Figure 4 shows the behavior of 16-QAM-OFDM data encoded directly on a TO-9 package blue LD after offset by a DC bias current.

Then, a collimated laser beam with an estimated divergence angle of 5.6° is delivered through an underwater channel 60 filled with fresh tap water similar to the shape of clear sea water. An LD 54 of 15 mW (11.8 dBm) output would be sufficient to overcome the attenuation in clear sea water. A water tank having dimensions of 0.6 m x 0.3 m x 0.3 m is made of glass. The actual light propagation distance was extended to 5.4 m using reflective mirrors installed at both ends of the tank. By using a 50 mm focal length lens, the output signal from the underwater channel was focused into a highly sensitive APD 62 with an active diameter of 0.5 mm and a responsivity of ~5 A/W at 450 nm. The output level of the transmitted laser light was controlled through a neutral density filter.

After optical-to-electrical conversion, the received analog waveform is captured and converted to a digital signal by a digital serial analyzer 65 with a sampling rate of 100 GSa/s. After removal of the cyclic prefix in module 66 and further processing by serial-parallel module 68, the received OFDM signal is passed to FFT module 70 where it is transformed to frequency domain subcarriers and symbol demapping module 72 ) through which it is mapped back to the QAM symbol. Finally, a parallel-to-serial module 74 is used to convert the QAM symbols to serial on-off keying data 76. Constellation, error vector magnitude (EVM), signal-to-noise ratio (SNR) and bit error rate (BER) were measured and used to evaluate the performance of the present underwater wireless optical communication system. All measurements were performed under normal room lighting, and an optical interference filter was not used to suppress ambient light.

The light-current-voltage (LIV) characteristics of the TO-9 package and fiber-pigtailed blue LD are shown in FIG. 5(a). The critical current and differential quantum efficiency were 3 mmA and 0.27 W/A, respectively. Figure 5(b) shows a graph of lasing spectrum versus wavelength at 250 C under various bias currents. Bias current was measured using an Ocean Optics HR4000 spectrometer. The nominal spectral width of the blue LD was 0.9 nm. The maximum emission wavelength was observed near 448.4 nm with the blue LD biased at 40 mA and slightly red-shifted with increasing bias current. The optimal operating wavelength in an underwater optical link depends on the turbidity of the water, which varies greatly between geographic locations.

The overall frequency response of the system including laser driver 54, underwater channel 60 and APD 62 was evaluated to determine the maximum allowable modulation bandwidth for encoding an OFDM signal. 6 shows the small-signal modulation response of blue laser diode 54 at various bias currents, measured using a vector network analyzer. When the bias current is increased, no significant expansion is observed in the LD modulation bandwidth due to the combined bandwidth limitation of the LD driver 54 and the 1-GHz cut-off frequency of the APD 62. The reduced throughput intensity in the high frequency region is also due to bandwidth limitations. As a result, limiting this sets an upper limit on the allowable OFDM bandwidth. As indicated by the dashed line in the figure, the maximum -3 dB bandwidth occurred around 1.1 GHz.

The performance of the blue LD 54 with 1-GHz 16-QAM-OFDM data at various bias currents was first evaluated in free space. Both the laser bias current and the amplitude of the modulated signal were adjusted to evaluate the optimal operating conditions. In low bias operation, clipping of the modulated signal degrades the BER of the encoded 16-QAM-OFDM data. In addition, excessive driving of the blue LD reduces the throughput response and eventually lowers the power of the high-frequency subcarrier of 16-QAM-OFDM data, which causes an increase in transmission BER. The highest data rate was achieved when the bias current of the blue LD and the peak-to-peak voltage of the modulated signal were set to Vbias = 5.01 V (Ibias = 70 mA) and Vpp = 0.4 V, respectively.

7(a) and 7(b) show BER performance of 1-GHz 16-QAM-OFDM data delivered by blue LD 54 as a function of laser bias current and constellation diagram at 70 mA. is showing Figure 7(a) shows the measured BER versus laser diode current. Fig. 7(b) shows a constellation diagram at 70 mA.

To implement the underwater 16-QAM-OFDM transmission, the bias current of the blue LD 54 was maintained at an optimal operating condition of 70 mA. In order to evaluate the overall 16-QAM-OFDM transmission performance on a 5.4 m underwater communication channel, the measured BER, SNR and constellation are shown in FIGS. 8(a), 8(b) and 8(c). showed up

Figure 8(a) shows the measured BER vs. modulation bandwidth of 16-QAM-OFDM data. As shown, by increasing the data bandwidth from 0.8 GHz to 1.2 ^GHz , the transmission capacity of the TO-9 package and fiber pigtail blue LD ^is increased to 3.2 Gbit/s to 4.8 Gbit/s. Increasing the data bandwidth further to 1.3 GHz increased the BER to 4.8 × 10 ^-3 , which was slightly higher than the FEC required BER of 3.8 × 10 ^-3 . Therefore, to meet the FEC criteria, the allowed bandwidth of the delivered 16-QAM-OFDM was 1.2 GHz and the corresponding data rate was 4.8 Gbit/s.

Figure 8(b) shows the measured electrical signal-to-noise ratio (SNR) of received 16-QAM-OFDM data as a function of subcarrier index. The measured SNR profile exhibited a negative slope and followed the overall frequency response shown in FIG. 3 . The SNR remained high at small subcarrier indexes (low frequencies) and was inversely proportional to the subcarrier index. The average SNR at 70 mA was around 15.6 dB, which is higher than the average SNR of 15.19 dB required by FEC decoding.

8(c) shows a constellation diagram of a 1.2 GHz 16-QAM-OFDM signal transmitted through a 5.4 m underwater channel. As shown in the figure, a clear constellation can be obtained.

Scattering effects such as temporal pulse spread (inter-symbol interference) were also evaluated in relation to the overall system performance. 9 shows the measured BER versus link distance for a 1.2 GHz 16-QAM-OFDM signal. The purpose of this evaluation is to evaluate whether the BER performance degrades as a function of link distance. It should be noted that as the link distance increased from 0.6 m to 5.4 m, the received optical power was kept constant using the variable attenuator. As shown in Figure 9, a relatively flat BER was observed.

Because the transmitter beam is collimated to a very small diameter, this example of a UWOC system required good pointing accuracy between transmitter and receiver. Expanding the transmitter beam to reduce the directive accuracy requirements results in a weaker beam at the receiver, which will reduce performance at longer ranges. In more turbid waters, high concentrations of organic and inorganic particulates increase scattering and can cause significant temporal dispersion, which is a form of inter-symbol interference that reduces orientation accuracy as the beam spreads, resulting in low SNR and poor BER. can be thought of as However, experimental results show that scattering during the communication link in 5.4 m clear water does not affect the BER performance of the 1.2-GHz 16-QAM-OFDM signal. For a 4.8 Gbit/s UWOC system, a measured EVM of 16.5 % and a BER of 2.6×10 ^-3 both pass the FEC criteria.

10 shows a compact integrated underwater lighting, irradiation and optical communication system of the present invention. The power supply 70 , control circuit 72 , laser diode module 74 , and focusing optics 76 may be housed in a waterproof housing 78 . The laser diode module 74 may have a non-dedicated integrated receiver unit and distance range measurement. Control circuit 72 integrates the functions of power stabilization, signal amplification and bias tee combination to drive laser diode module 74. Phosphors can be incorporated into the focusing optics to produce white light.

In another embodiment of the present invention, the transmission module may be configured to have different interference degrees (such as edge-emitting lasers, vertical-cavity surface emitting lasers, and superluminescent diodes). degree of coherency). Transmitting modules can be independent or in an array to increase light output. In an embodiment of the invention, a single node 450 nm radar diode had better performance compared to a multi node 405 nm violet laser.

Transmission media include, but are not limited to, water, oil, and other organic liquids. Laser wavelengths can cover a wide range of wavelengths tailored to the specific low absorption and scattering characteristics of the transmission medium.

In other embodiments, the photodetector can be an amplified bias photodetector, or a bias photodetector, or a UV-enhanced bias photodetector. The photodetector may be based on, but not limited to, Si, or GaAs, or GaN, or other III/V materials.

In some embodiments of the invention, the receiving module may include one or multiple photodetectors. When using multiple laser diodes in the transmit module and/or multiple photodetectors in the receive module, UWOC systems can achieve higher data rates (5 Gbit/s) when using optical multi-input multi-output technology. or longer) and longer transmission distances (more than 20 meters) can be achieved. When using multiple laser diodes in the transmitting module and/or multiple photodetectors in the receiving module, the UWOC system uses wavelength division multiplexing (WDM) technology to achieve higher data rates (5 Gbit/s or greater). can be achieved

In another embodiment of the present invention, a UWOC system utilizing multiple laser diodes including at least two purple, blue, green, yellow or red emitting laser diodes can produce white light for both underwater vision and communication. .

In another embodiment of the present invention, a UWOC system using a purple or blue laser in conjunction with a phosphor in a transmit module to generate white light may be used for both underwater vision and communications. Phosphor materials used for generating white light refer to a kind of color conversion material that can produce blue, green, yellow or red when excited by a purple or blue laser. By mixing these colors, white light having various color rendering indexes and color temperatures can be obtained.

Claims (20)

A method of providing an underwater light source and data communication system, the method comprising:
generating a signal to drive a plurality of laser diodes in a transmission module to provide a white light illuminated area of sufficient intensity and duration to illuminate an underwater area of interest during aquatic activity, the laser diodes comprising a power supply, control circuitry and a focusing optic, the plurality of laser diodes serving as a white light source for illuminating an underwater structure for underwater vision applications; and
using the plurality of laser diodes, control circuitry and focusing optics within an optical communication system to continuously illuminate the underwater area of interest with white light while also conveying information away from the underwater area of interest;
Using the plurality of laser diodes, control circuitry and focusing optics:
optically directing, by the focusing optics, at least a portion of the light from the plurality of laser diodes away from the watertight housing and towards a remote underwater location;
at the remote underwater location, receiving at least a portion of the optically transmitted light and further processing the received light into an information signal to generate an optically transmitted data stream during the underwater activity; and
receiving, at a receiving module embedded within the watertight housing, light from the remote underwater location to perform duplex communication using a plurality of photodetectors within the receiving module. According to claim 1,
wherein the underwater area of interest comprises an underwater vehicle, a diver, or the seabed. According to claim 2,
The method of claim 1 , wherein optically directing includes focusing a light beam and directing the focused light beam towards the remote underwater location. According to claim 3,
wherein the focused light beam defines a plurality of parallel beams. According to claim 4,
wherein the receiving at the remote underwater location comprises directing the light beam onto a silicon-based avalanche photodiode. According to claim 1,
The method of claim 1 , wherein the optical communication system includes a spectral efficient modulation scheme. According to claim 6,
Wherein the modulation scheme comprises QAM-OFDM. According to claim 1,
wherein the plurality of laser diodes include a plurality of purple or blue light lasers, and a phosphor material is used to color convert light from the plurality of purple or blue light lasers to white light. According to claim 1,
wherein the plurality of laser diodes include red, green and blue lasers. According to claim 1,
wherein the plurality of laser diodes comprises an ultraviolet laser. As an underwater light system, the light system comprises:
a watertight housing containing a power unit and control circuit;
A transmission module embedded in the waterproof housing, wherein the transmission module receives a data stream and controls a laser diode light source to provide an optical signal, and at the same time provide illumination that serves as a white light source for underwater vision applications, wherein the underwater vision Applications include the transmission module for remote viewing of underwater structures;
a transmission lens within the housing for focusing and directing the optical signal towards a remote underwater location;
A first at the remote underwater location for receiving and processing the light signal to generate the data stream while the laser diode light source simultaneously illuminates the underwater structure to perform remote underwater vision in proximity to the laser diode light source. receiving module; and
and a second receiving module within the watertight housing comprising a plurality of photodetectors for receiving light from the remote underwater location to perform communication with the remote underwater location. According to claim 11,
wherein the first receiving module includes a receiving lens for focusing the optical signal towards a silicon avalanche photodiode. According to claim 11,
wherein the laser diode light source is housed on an underwater vehicle or structure or a diver. According to claim 11,
The optical system of claim 1 , wherein the laser diode light source includes a plurality of violet to blue light lasers. According to claim 11,
wherein the transmission module processes the data stream in a spectrally efficient modulation scheme to speed data transfer. According to claim 11,
wherein the laser diode light source includes red, green and blue lasers. According to claim 11,
The optical system of claim 1, wherein the laser diode light source comprises an ultraviolet laser. As an underwater light system,
a transmitter housed in a watertight housing together with a power supply and control circuitry, said transmitter receiving a data stream and controlling a laser diode white light source to provide an optical signal;
a lens within the watertight housing for focusing and directing the optical signal toward a remote underwater location;
Receive the light signal to generate the data stream while the white light source simultaneously illuminates an area of interest with white light of sufficient intensity and duration to perform remote underwater observation in close proximity to the light source using a remote underwater vision device. a first receiver at the remote underwater location for processing and processing; and
and a second receiver within the watertight housing comprising a plurality of photodetectors for receiving light from the remote underwater location to perform communication with the remote underwater location. According to claim 18,
An underwater optical system further comprising a receiving lens for focusing and transmitting the optical signal towards a photodiode. According to claim 18,
wherein the light source comprises red, green and blue lasers, or comprises an ultraviolet laser.

Images