TECHNIQUES FOR GALVO AFE WITH ENHANCED DYNAMIC RANGE CONTROL AND IMPROVED SENSITIVITY TO ELECTROMAGNETIC INTERFERENCE

A LIDAR system includes an actuator assembly and actuator position tracking circuitry. The actuator position tracking circuity includes a light emitting diode (LED) to emit a first signal toward an actuator, a photodiode to receive a second signal based on a position of the actuator and generate an output signal, and at least one front-end electronics to produce a low-impedance analog electrical signal based on the output signal.

TECHNICAL FIELD

The present disclosure relates generally to light detection and ranging (LIDAR) systems, and more particularly to systems and methods for enhanced galvanometer (Galvo) Analog Front-End (AFE) electronics.

BACKGROUND

Frequency-Modulated Continuous-Wave (FMCW) LIDAR systems provide precise and reliable range, direction, and reflectance measurements that can be used for obstacle avoidance or measuring characteristics such as dimensions and reflectivity of objects in a scene within the sensor's field-of-view (FoV). FMCW LIDAR systems use an optical scanner that includes scanning mirrors that rotate along an axis using actuators, such as galvanometers. To control the movement and position of the scanning mirrors, galvanometers use AFE electronics. The AFE includes an amplifier that drives the movement of the galvanometer mirror, and feedback electronics that ensure that the mirror is moving accurately and in the correct position.

DETAILED DESCRIPTION

According to some embodiments, the LIDAR system described herein may be implemented in any sensing market, such as, but not limited to, transportation, manufacturing, metrology, medical, virtual reality, augmented reality, and security systems. According to some embodiments, the described LIDAR system is implemented as part of a front-end of frequency modulated continuous-wave (FMCW) device or Time of Flight (ToF) device that assists with spatial awareness for automated driver assist systems, or self-driving vehicles.

As discussed above, actuators, such as galvanometers (galvos), use AFE electronics to control the movement of a galvo mirror in laser scanning systems. The galvo AFE is an important component in laser scanning systems, as it determines the accuracy and stability of the laser beam's movement over the scan field. The galvo AFE may include optical position sensors, which are devices that use changes in light to determine the position or displacement of an object (e.g., the galvo mirror). Optical position sensors typically include a light source, such as an LED, and a photo detector or series of photo detectors, such as a photodiode, which is positioned in close proximity to a translucent or reflective code disk or opaque disk or other feature that changes light incident on the photodetectors as a function of shaft rotation. As the disk rotates, it modulates the light that reaches the photo detector, producing an electrical signal (e.g., a current signal) that is proportional to the angular position of the shaft.

A challenge found with conventional systems is that the galvo has a “passive” circuit board connected through a connector a main circuit board that includes “active” components. The passive circuit board includes the LED and photodiodes, but the remaining AFE components for driving position and sensing position are on the main circuit board. The issue with this partition is that it routes high-impedance sense nodes through the connector to achieve a given form factor for the final LiDAR design. Unfortunately, connectors carrying high-impedance nodes are sensitive to electromagnetic emissions or other interferers and cause reduced accuracy due to electrical noise during electromagnetic compatibility (EMC) qualification. In addition, the electromagnetic emissions on the connectors reduce the dynamic range and flexibility of the galvo AFE.

To eliminate routing high impedance signals through the connector, discussed herein is an approach that enhances the galvo AFE by routing low impedance analog signals or digital signals through the connector to reduce EMI susceptibility of the overall system and improve the dynamic range and flexibility of the galvo AFE. The approach partitions the front-end electronics such that sensitive analog lines are included on a small board mounted directly to the galvo and their outputs are feed through the connector to the main board. In some embodiments, the drive lines through the connector are differential (or pseudo-differential) in addition to being driven by low impedance sources. The approach enables dynamic range adjustment by controlling the LED drive voltage and the reference voltage the first stage sense amplifier in a transimpedance amplifier (TIA) discussed below. In some embodiments, the amplifier supply voltage rails are reduced by moving the front-end electronics closer to the LED and photodiode. In some embodiments, the approach controls bias voltages to improve the flexibility of the front-end and adjusts its sensitivity. In some embodiments, the approach controls the voltage using a digital to analog converter (DAC). In turn, the approach improves signal integrity, increases position knowledge accuracy, increases position knowledge resolution, and enhances dynamic range optimization.

FIG.1is a block diagram illustrating an example of a LIDAR system, according to some embodiments. The LIDAR system100includes one or more of each of a number of components, but may include fewer or additional components than shown inFIG.1. One or more of the components depicted inFIG.1can be implemented on a photonics chip, according to some embodiments. The optical circuits101may include a combination of active optical components and passive optical components. Active optical components may generate, amplify, and/or detect optical signals and the like. In some examples, the active optical component includes optical beams at different wavelengths, and includes one or more optical amplifiers, one or more optical detectors, or the like. In some embodiments, one or more LIDAR systems100may be mounted onto any area (e.g., front, back, side, top, bottom, and/or underneath) of a vehicle to facilitate the detection of an object in any free-space relative to the vehicle. In some embodiments, the vehicle may include a steering system and a braking system, each of which may work in combination with one or more LIDAR systems100according to any information (e.g., one or more rigid transformations, distance/ranging information, Doppler information, etc.) acquired and/or available to the LIDAR system100. In some embodiments, the vehicle may include a vehicle controller that includes the one or more components and/or processors of the LIDAR system100.

Free space optics115may include one or more optical waveguides to carry optical signals, and route and manipulate optical signals to appropriate input/output ports of the active optical circuit. The free space optics115may also include one or more optical components such as taps, wavelength division multiplexers (WDM), splitters/combiners, polarization beam splitters (PBS), collimators, couplers or the like. In some examples, the free space optics115may include components to transform the polarization state and direct received polarized light to optical detectors using a PBS, for example. The free space optics115may further include a diffractive element to deflect optical beams having different frequencies at different angles along an axis (e.g., a fast-axis).

In some examples, the LIDAR system100includes an optical scanner102that includes one or more scanning mirrors that are rotatable along an axis (e.g., a slow-axis) that is orthogonal or substantially orthogonal to the fast-axis of the diffractive element to steer optical signals to scan an environment according to a scanning pattern. For instance, the scanning mirrors may be rotatable by one or more galvanometers as discussed herein. In some embodiments, the galvanometer AFE are located within optical scanner102. In some embodiments, some of the galvanometer AFE (e.g., main board components) are located on motion control system105(discussed below). Objects in the target environment may scatter an incident light into a return optical beam or a target return signal. The optical scanner102also collects the return optical beam or the target return signal, which may be returned to the passive optical circuit component of the optical circuits101. For example, the return optical beam may be directed to an optical detector by a polarization beam splitter. In addition to the mirrors and galvanometers, the optical scanner102may include components such as a quarter-wave plate, lens, anti-reflective coated window or the like.

To control and support the optical circuits101and optical scanner102, the LIDAR system100includes LIDAR control systems110. The LIDAR control systems110may include a processing device for the LIDAR system100. In some examples, the processing device may be one or more general-purpose processing devices such as a microprocessor, central processing unit, or the like. More particularly, the processing device may be complex instruction set computing (CISC) microprocessor, reduced instruction set computer (RISC) microprocessor, very long instruction word (VLIW) microprocessor, or processor implementing other instruction sets, or processors implementing a combination of instruction sets. The processing device may also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), network processor, or the like.

In some examples, the LIDAR control system110may include a processing device that may be implemented with a DSP, such as signal processing unit112. The LIDAR control systems110are configured to output digital control signals to control optical drivers103. In some examples, the digital control signals may be converted to analog signals through signal conversion unit106. For example, the signal conversion unit106may include a digital-to-analog converter. The optical drivers103may then provide drive signals to active optical components of optical circuits101to drive optical sources such as lasers and amplifiers. In some examples, several optical drivers103and signal conversion units106may be provided to drive multiple optical sources. In some embodiments, optical drivers103includes a laser driver circuit300shown inFIG.3.

The LIDAR control system110is also configured to output digital control signals for the optical scanner102. A motion control system105may control the galvanometers of the optical scanner102based on control signals received from the LIDAR control systems110. For example, a digital-to-analog converter may convert coordinate routing information from the LIDAR control systems110to signals interpretable by the galvanometers in the optical scanner102. In some examples, a motion control system105may also return information to the LIDAR control systems110about the position or operation of components of the optical scanner102. For example, an analog-to-digital converter may in turn convert information about the galvanometers' position to a signal interpretable by the LIDAR control systems110.

The LIDAR control systems110are further configured to analyze incoming digital signals. In this regard, the LIDAR system100includes optical receivers104to measure one or more beams received by optical circuits101. For example, a reference beam receiver may measure the amplitude of a reference beam from the active optical component, and an analog-to-digital converter converts signals from the reference receiver to signals interpretable by the LIDAR control systems110. Target receivers measure the optical signal that carries information about the range and velocity of a target in the form of a beat frequency, modulated optical signal. The reflected beam may be mixed with a second signal from a local oscillator. The optical receivers104may include a high-speed analog-to-digital converter to convert signals from the target receiver to signals interpretable by the LIDAR control systems110. In some examples, the signals from the optical receivers104may be subject to signal conditioning by signal conditioning unit107prior to receipt by the LIDAR control systems110. For example, the signals from the optical receivers104may be provided to an operational amplifier for amplification of the received signals and the amplified signals may be provided to the LIDAR control systems110.

In some embodiments, the LIDAR system100may additionally include one or more imaging devices108configured to capture images of the environment, a global positioning system109configured to provide a geographic location of the system, or other sensor inputs. The LIDAR system100may also include an image processing system114. The image processing system114can be configured to receive the images and geographic location, and send the images and location or information related thereto to the LIDAR control systems110or other systems connected to the LIDAR system100.

In operation according to some examples, the LIDAR system100is configured to use nondegenerate optical sources to simultaneously measure range and velocity across two dimensions. This capability allows for real-time, long range measurements of range, velocity, azimuth, and elevation of the surrounding environment.

In some embodiments, the scanning process begins with the optical drivers103and LIDAR control systems110. The LIDAR control systems110instruct, e.g., via signal processor unit112, the optical drivers103to independently modulate one or more optical beams, and these modulated signals propagate through the optical circuits101to the free space optics115. The free space optics115directs the light at the optical scanner102that scans a target environment over a preprogrammed pattern defined by the motion control system105. The optical circuits101may also include a polarization wave plate (PWP) to transform the polarization of the light as it leaves the optical circuits101. In some examples, the polarization wave plate may be a quarter-wave plate or a half-wave plate. A portion of the polarized light may also be reflected back to the optical circuits101. For example, lensing or collimating systems used in LIDAR system100may have natural reflective properties or a reflective coating to reflect a portion of the light back to the optical circuits101.

Optical signals reflected back from an environment pass through the optical circuits101to the optical receivers104. Because the polarization of the light has been transformed, it may be reflected by a polarization beam splitter along with the portion of polarized light that was reflected back to the optical circuits101. In such scenarios, rather than returning to the same fiber or waveguide serving as an optical source, the reflected signals can be reflected to separate optical receivers104. These signals interfere with one another and generate a combined signal. The combined signal can then be reflected to the optical receivers104. Also, each beam signal that returns from the target environment may produce a time-shifted waveform. The temporal phase difference value between the two waveforms generates a beat frequency measured on the optical receivers104(e.g., photodetectors).

The analog signals from the optical receivers104are converted to digital signals by the signal conditioning unit107. These digital signals are then sent to the LIDAR control systems110. A signal processing unit112may then receive the digital signals to further process and interpret them. In some embodiments, the signal processing unit112also receives position data from the motion control system105and galvanometers as well as image data from the image processing system114. The signal processing unit112can then generate 3D point cloud data (sometimes referred to as, “a LIDAR point cloud”) that includes information about range and/or velocity points in the target environment as the optical scanner102scans additional points. In some embodiments, a LIDAR point cloud may correspond to any other type of ranging sensor that is capable of Doppler measurements, such as Radio Detection and Ranging (RADAR). The signal processing unit112can also overlay 3D point cloud data with image data to determine velocity and/or distance of objects in the surrounding area. The signal processing unit112also processes the satellite-based navigation location data to provide data related to a specific global location.

FIG.2is a time-frequency diagram of FMCW scanning signals that can be used by a LIDAR system according to some embodiments of the present disclosure. The FMCW scanning signals200and202may be used in any suitable LIDAR system, including the system100, to scan a target environment. The scanning signal200may be a triangular waveform with an up-chirp and a down-chirp having a same bandwidth Δƒsand period Ts. The other scanning signal202is also a triangular waveform that includes an up-chirp and a down-chirp with bandwidth Δƒsand period Ts. However, the two signals are inverted versions of one another such that the up-chirp on scanning signal200occurs in unison with the down-chirp on scanning signal202.

FIG.2also depicts example return signals204and206. The return signals204and206, are time-delayed versions of the scanning signals200and202, where Δt is the round trip time to and from a target illuminated by scanning signal201. The round trip time is given as Δt=2R/ν, where R is the target range and ν is the velocity of the optical beam, which is the speed of light c. The target range, R, can therefore be calculated as R=c(Δt/2).

In embodiments, the time delay Δt is not measured directly, but is inferred based on the frequency difference values between the outgoing scanning waveforms and the return signals. When the return signals204and206are optically mixed with the corresponding scanning signals, a signal referred to as a “beat frequency” is generated, which is caused by the combination of two waveforms of similar but slightly different frequencies. The beat frequency indicates the frequency difference value between the outgoing scanning waveform and the return signal, which is linearly related to the time delay At by the slope of the triangular waveform.

If the return signal has been reflected from an object in motion, the frequency of the return signal will also be effected by the Doppler effect, which is shown inFIG.2as an upward shift of the return signals204and206. Using an up-chirp and a down-chirp enables the generation of two beat frequencies, Δƒupand Δƒdn. The beat frequencies Δƒupand Δƒdnare related to the frequency difference value cause by the range, ΔƒRange, and the frequency difference value cause by the Doppler shift, ΔƒDoppler, according to the following formulas:

Thus, the beat frequencies Δƒupand Δƒdncan be used to differentiate between frequency shifts caused by the range and frequency shifts caused by motion of the measured object. Specifically, ΔƒDoppleris the difference value between the Δƒupand Δƒdnand the ΔƒRangeis the average of Δƒupand Δƒdn.

The range to the target and velocity of the target can be computed using the following formulas:

In the above formulas, λc=c/ƒcand ƒcis the center frequency of the scanning signal. The beat frequencies can be generated, for example, as an analog signal in optical receivers104of system100. The beat frequency can then be digitized by an analog-to-digital converter (ADC), for example, in a signal conditioning unit such as signal conditioning unit107in LIDAR system100. The digitized beat frequency signal can then be digitally processed, for example, in a signal processing unit, such as signal processing unit112in system100.

In some scenarios, to ensure that the beat frequencies accurately represent the range and velocity of the object, beat frequencies can be measured at a same moment in time, as shown inFIG.2. Otherwise, if the up-chirp beat frequency and the down-chirp beat frequencies were measured at different times, quick changes in the velocity of the object could cause inaccurate results because the Doppler effect would not be the same for both beat frequencies, meaning that equations (1) and (2) above would no longer be valid. In order to measure both beat frequencies at the same time, the up-chirp and down-chirp can be synchronized and transmitted simultaneously using two signals that are multiplexed together.

FIG.3is a block diagram illustrating an example actuator tracking system300including analog front-end electronics positioned in proximity to galvo position drivers and sensors, according to some embodiments of the present disclosure. Position sensing requires the sensing of current (e.g., receive signal) through photodiodes315as well as driving LED320to provide a signal (e.g., transmit signal) for the position sensor photodiodes to detect. The combination of drive and sense are used to interpret the position of the galvo with respect to the galvo's physical limits. System300incorporates the most sensitive part of the electronics (front-end electronics325) associated with galvo position sensing within or on a galvo sub-assembly310to be closer to the galvo position sensing photodiodes315and LED320on galvo sub-assembly310. In some embodiments, front-end electronics325is on a same circuit board as photodiodes315and LED320. In some embodiments, front-end electronics325is on a separate circuit board coupled to photodiodes315and LED320. By moving the front-end electronics closer, the system is more robust to electromagnetic interference. Furthermore, the front-end electronics may operate on a lower-supply voltage than the main processing and control circuity of the main board340to reduce power while also providing a mechanism for optimizing the dynamic range of the front-end electronics (e.g., LED transmitter/TIA). This level of flexibility is helpful to improve position sensing in a LiDAR system.

In some embodiments, front-end electronics325includes an LED driver and a transimpedance amplifier. The transimpedance amplifier (TIA) is a type of amplifier that converts a current input signal (from a photodiode) into a voltage output signal. A TIA may be used to amplify the weak signals from photodetectors, such as photodiodes and phototransistors, into a form that can be easily processed by subsequent circuits. The transimpedance gain of a TIA is typically specified in ohms, and it is the ratio of the output voltage to the input current. TIAs often incorporate feedback to stabilize their gain and bandwidth and improve their performance in the presence of noise and other disturbances.

In some embodiments, the TIA includes programmable common mode amplifier circuitry. The common mode indicates a voltage common to both input terminals of an amplifier. In some embodiments, the programmable common mode amplifier circuitry is external to the TIA and included as part of front-end electronics325. In some embodiments, the programmable common mode sets the common mode into different electronic dispersion compensation (EDC) ranges.

In some embodiments, bias voltages are adjusted in front-end electronics325where one DC bias adjusts the LED current and one DC bias compensates the TIA stage for the adjusted LED current (e.g., DC shift). In some embodiments, the bias voltages are adjusted to keep a common mode output that matches an analog-to-digital (ADC) converter that the TIA is driving. In some embodiments, front-end electronics325dynamically adjusts the bias voltage based on, for example, a degradation in LED320(e.g., at system startup). In some embodiments, front-end electronics325dynamically adjusts (calibrates) the bias voltage based on, for example, different scan patterns with different field of views. In some embodiments, system300provides a level of modularity because system300may use photodiodes with different sensitivity, LEDs with different wavelengths, or a combination thereof without affecting other components.

By moving front-end electronics325closer to photodiodes315and LED320, signals on connector330that pass to/from main board340are low impedance and are therefore less susceptible to EMI. Main board340includes motor driver345to drive the motor of galvo sub-assembly310, and power supply350provides power to galvanometer. In some embodiments, front-end electronics325is powered by a different supply voltage than the motor drive of galvo sub-assembly310. As such, transients on the motor drive voltage do not couple over to the supply voltage of front-end electronics325. Actuator control algorithm355provides and receives position information to/from front-end electronics325.

In some embodiments, front-end electronics325includes an encoder that performs feedback control of the LED intensity to compensate for aging effects, where measurement of the sum of the photodiode signals allows measurement of the LED intensity. In some embodiments, front-end electronics325performs on/off modulation of the LED to enable correlated double sampling. The on/off modulation provides various benefits such as interleaved measurement of signal and noise, and modulation of the signal to high frequency to reject 1/f and other low-frequency noise sources.

In some embodiments, front-end electronics325monitors the noise levels on the photodiodes to detect changes introduced by external interference or part failures. In some embodiments, front-end electronics325includes a fault signal safety mechanism that is generated when, for example, the LED intensity (or compensating signal) has changed by more than a configurable threshold; the measured noise amplitude on any of the photodiodes exceeds a configurable threshold; the measured signal level on any of the photodiodes drops below a configurable threshold, or a combination thereof.

FIG.4is a block diagram illustrating an example actuator tracking system400in which motor driver circuitry is incorporated at galvo sub-assembly310, according to some embodiments of the present disclosure. System400depicts motor driver345on galvo sub-assembly310. In this embodiment, signal integrity is further enhanced by eliminating the need to send high current pulses through connector330. Instead, main board340sends an average current pulse (e.g., pulse-width modulated (PWM) signal) through connector330to control motor driver345that, in turn, reduces transients on connector330.

FIG.5is a block diagram illustrating an example of a galvo sub-assembly310with incorporated front-end electronics, according to some embodiments of the present disclosure. As depicted, front-end electronics325may include LED driver222to receive a low-impedance signal from connectors430to control the LED320. The front-end electronics325may also include a TIA316to amplify an output signal (e.g., an electrical current) and to generate a low impedance output signal. By incorporating the TIA316near the photodiodes315, the traces are shortened to minimize the amount of noise picked up in the photodiode315output signal and amplified by the TIA316.

In some embodiments, the front-end electronics325further includes programmable common mode amplifier circuitry318either as part of the TIA316or as a separate component. The common-mode amplifier318may be a type of differential amplifier with two inputs that amplifies the average of the voltage between the two input signals, rejecting any voltage differences between the inputs. Accordingly, the small signal of the photodiode315may be superimposed on a larger, varying common-mode voltage. The common mode amplifier318may allow the differential signal (the signal of interest) to be amplified (e.g., by TIA316) while the common-mode signal (the noise) is rejected, resulting in a cleaner, stronger signal. In some examples, the common mode indicates a voltage common to both input terminals of an amplifier. In some embodiments, the programmable common mode sets the common mode into different electronic dispersion compensation (EDC) ranges.

In some embodiments, the LED320strength is adjustable, based on a signal to the LED driver322, which in turn also adjust the signal of photodiodes315. The adjusted output signal of the photodiodes315further adjusts the gain of the circuit. However, this will result in a stronger DC level which should be accounted for. Accordingly, one DC biases may be used to set the LED320current, to compensate the TIA stage so that its output is maintained at a common mode that matches an analog to digital convert to which it is being driven. Accordingly, the adjustable LED signal and the adjustable biases to account for the changes in DC signal provide for programmable ranges that compensates on the transmit side and the receive side.

In some embodiments, the galvo sub-assembly310include a galvo mirror348to direct an output beam to a field of view of a LIDAR system. The galvo mirror348may be moved or actuated by a motor346. The motor346may be controlled by a motor driver345that received a control signal and drives a voltage to the motor346to position the galvo mirror348according to the control signal. In some examples, the motor driver345may also receive feedback from the motor346regarding the position of the motor346and thus the galvo mirror348. The motor driver345may return the feedback signal to, for example, an actuator control algorithm which may use the feedback signal along with the amplified photodiode315signal to determine a position of the galvo mirror348and to adjust or calculate next movements of the galvo mirror348and moto346based on a scan pattern of the LIDAR system.

FIG.6is a flow diagram illustrating an example method600of operating a galvo sub-assembly with incorporated front-end electronics, according to some embodiments of the disclosure. Method600may begin at block610, where an LED transmits a light signal toward an actuator. The LED may be driven by a local LED driver incorporated on the galvo sub-assembly of a LIDAR system. The LED driver may include a DC bias to control an intensity of the LED which may, in turn, be controlled by circuitry at a main electronics board of the LIDAR system.

At block620, a photodetector generates an output signal based on the light signal and position of the actuator. For example, the LED signal may be modulated, reduced, or otherwise encoded based on a position of the actuator. The output of the photodetector may be a current that is dependent on the intensity of the light received by the photodetector.

At block630, front-end electronics process the output signal of the photodetector to produce a low-impedance analog electrical signal, wherein the front-end electronics are integrated within an actuator position tracking assembly (e.g., at the galvo sub-assembly). In some embodiments, the front-end electronics incorporated on the galvo sub-assembly includes an analog signal amplifier coupled to the photodiode to amplify an output signal received from the photodiode and an LED driver coupled to the light emitting diode. In some embodiments, the analog signal amplifier includes a trans-impedance amplifier and a common mode amplifier circuit. In some embodiments, the actuator position tracking assembly further includes a motor driver coupled to a motor of the actuator.

The preceding description sets forth numerous specific details such as examples of specific systems, components, methods, and so forth, in order to provide a good understanding of several embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that at least some embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known components or methods are not described in detail or are presented in simple block diagram format in order to avoid unnecessarily obscuring the present disclosure. Thus, the specific details set forth are merely exemplary. While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any embodiment of the present disclosure or of what may be claimed, but rather as descriptions of features specific to particular embodiments of the present disclosure. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Particular embodiments may vary from these exemplary details and still be contemplated to be within the scope of the present disclosure.