Wave scanning optic

A wave scanning optic is formed to have an angular reflectance or refraction that produces a uniform line scan during rotation of the optic, such that the optic is operable for seamless multidirectional scanning. The wave scanning optic includes a rotatable body defining a central axis of rotation about which the rotatable body rotates during scanning, and an optical surface formed on the rotatable body and having a wavy pattern defined by one or more lobes that protrude outwardly from the rotatable body. The optical surface has a continuous pattern with an angular frequency that varies along a radial distance from the central axis of rotation. The optical surface is configured to emit and/or receive light in one or more incident directions.

FIELD OF DISCLOSURE

The disclosure relates to laser scanning optics.

DESCRIPTION OF THE RELATED ART

Various applications may use optical scanning systems to read and record information. Exemplary application include light or laser detection and ranging, i.e. LIDAR or LADAR, hyperspectral applications, industrial products, and consumer products, such as laser printers, laser bar code readers, etc. Optical scanning systems use scanning optics that are configured to direct a laser beam toward a target scan track. The scanning optics typically have precisely angled reflecting surfaces such that rotation of the optic will cause an incident light beam to be reflected by the reflecting surfaces.

Conventional scanning optics include rotating prisms and polygonal or faceted mirrors. In a rotating polygonal mirror, the point on each reflective surface, i.e. the facet, of the polygonal mirror where reflection of the light beam occurs is longitudinally shifted with respect to the light path of the incident beam as the polygonal mirror rotates. However, rotating prisms and polygonal mirrors may be deficient for some applications since rotating prisms and polygonal mirrors are limited to unidirectional scanning. Another deficiency of using rotating prisms and polygonal mirrors is that the scanning operation may include pauses between scanning surfaces. Using polygonal or faceted mirrors may also result in undesirable angles between the facets in the scanning direction, i.e. facet angle errors, or pyramidal errors.

Another prior attempt to provide a scanning optic includes using fast steering mirrors and oscillating mirrors which are advantageous in providing fast multidirectional scanning operation. However, fast steering mirrors and oscillating mirrors may experience pauses in scanning, such as during a change in direction. Still another disadvantage of fast steering mirrors and oscillating mirrors is that they require complex control and feedback loops.

SUMMARY OF THE DISCLOSURE

The present application provides a wave shaped surface scanning optic or optical component that is formed to have an angular reflectance or refraction of an optical surface that produces a uniform line scan during rotation of the optic, such that the optic is operable for continuous multidirectional scanning without breaks in the scan pattern. The wave scanning optic is formed as a compact, single optical structure including a rotatable body defining a central axis of rotation about which the rotatable body rotates during scanning, and an optical surface formed on the rotatable body and having a wavy pattern defined by one or more lobes that protrude outwardly from the rotatable body. The optical surface has a continuous sinusoidal pattern with an angular frequency that varies along a radial distance from the central axis of rotation. The optical surface is configured to emit and/or receive light in one or more incident directions such that the wave scanning optic may be configured as both an emitter and a receiver.

The wave scanning optic is advantageous in providing a continuous and uniform line scan without complex control mechanisms. The amplitude and frequency of the sine wave optical surface pattern may be selected to achieve a predetermined scanning operation in one or more incident directions, i.e. the waviness of the optical surface pattern is formed to control the scanning angle range. Advantageously, facet angle errors and pyramidal errors are eliminated due to the pattern of the wavy optical surface for the wave scanning optic, in contrast to using conventional polygonal or faceted mirrors.

The pattern of the optical surface may also be used to achieve a desired rate of scanning. The scanning rate for the wave scanning optic may be increased by increasing the speed of rotation of the rotatable optic and/or by increasing the number of lobes formed on the rotatable body. One or more lobes may be provided. The wave scanning optic may have any suitable shape, such as a flat and wavy washer-like shape, or a cylinder.

According to an aspect of the disclosure, a wave scanning optic may include a wavy optical surface.

According to an aspect of the disclosure, a wave scanning optic may include one or more lobes.

According to an aspect of the disclosure, a wave scanning optic may be configured to provide multidirectional scanning during rotation of the wave scanning optic.

According to an aspect of the disclosure, a wave scanning optic may have an optical surface having a pattern that is formed as a radially-dependent sine wave period.

According to an aspect of the disclosure, a wave scanning optic may be formed to provide a continuous and uniform line scan during rotation of the wave scanning optic.

According to an aspect of the disclosure, a wavy optical surface of a wave scanning optic may be formed to provide a specific scanning operation.

According to an aspect of the disclosure, a scanning optic includes a rotatable body defining a central axis of rotation about which the rotatable body rotates during scanning, and an optical surface formed on the rotatable body and having a wavy pattern defined by one or more lobes that protrude outwardly from the rotatable body.

According to an embodiment in accordance with any paragraph(s) of this summary, the optical surface may have a continuous sinusoidal pattern with an angular frequency that varies along a radial distance from the central axis of rotation.

According to an embodiment in accordance with any paragraph(s) of this summary, the optical surface may be configured to emit and/or receive light in one or more incident directions.

According to an embodiment in accordance with any paragraph(s) of this summary, the one or more incident directions may correspond to points of impact of light that is emitted from or received on the optical surface as the rotatable body rotates during scanning.

According to an embodiment in accordance with any paragraph(s) of this summary, points of impact along any spoke of radial distance relative to the central axis of rotation are configured to provide a same scanning angle.

According to an embodiment in accordance with any paragraph(s) of this summary, the optical surface may be configured to emit and/or receive light over multiple paths simultaneously.

According to an embodiment in accordance with any paragraph(s) of this summary, the one or more incident directions include a horizontal direction, a vertical direction, and a diagonal direction between the horizontal direction and the vertical direction.

According to an embodiment in accordance with any paragraph(s) of this summary, the optical surface may be configured to both emit and receive light.

According to an embodiment in accordance with any paragraph(s) of this summary, an angular reflectance or refraction of the optical surface may provide a uniform line scan during rotation of the rotatable body.

According to an embodiment in accordance with any paragraph(s) of this summary, the continuous pattern may be periodic or aperiodic.

According to an embodiment in accordance with any paragraph(s) of this summary, the rotatable body may have a washer shape.

According to an embodiment in accordance with any paragraph(s) of this summary, the rotatable body may be cylindrical in shape.

According to an embodiment in accordance with any paragraph(s) of this summary, the one or more lobes may include a plurality of lobes.

According to an embodiment in accordance with any paragraph(s) of this summary, the scanning optic may be formed of a plurality of scanned refractive optical surfaces.

According to an embodiment in accordance with any paragraph(s) of this summary, the scanning optic may be arranged in a laser radar.

According to another aspect of the disclosure, a laser radar includes a rotatable optic defining a central axis of rotation about which the rotatable optic rotates during scanning, and an optical surface formed on the rotatable optic and having a wavy pattern with one or more lobes that protrude outwardly from the rotatable optic, the optical surface being configured to emit and/or receive light in one or more incident directions, and the optical surface having an angular reflectance or refraction that provides a uniform line scan during rotation of the rotatable optic.

According to still another aspect of the disclosure, a method of scanning includes rotating a rotatable optic about a central axis of rotation, the rotatable optic having an optical surface formed thereon that has a wavy pattern with one or more lobes that protrude outwardly from the rotatable optic, and emitting and/or receiving light in one or more incident directions.

According to an embodiment in accordance with any paragraph(s) of this summary, the method may include increasing a scan rate of the rotatable optic by at least one of increasing a number of the one or more lobes or increasing a speed of rotation of the rotatable optic.

According to an embodiment in accordance with any paragraph(s) of this summary, the method may include emitting and/or receiving light over multiple paths simultaneously.

According to an embodiment in accordance with any paragraph(s) of this summary, the method may include providing a uniform line scan during rotation of the rotatable optic via an angular reflectance or refraction of the optical surface.

To the accomplishment of the foregoing and related ends, the disclosure comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the disclosure. These embodiments are indicative, however, of but a few of the various ways in which the principles of the disclosure may be employed. Other objects, advantages and novel features of the disclosure will become apparent from the following detailed description of the disclosure when considered in conjunction with the drawings.

DETAILED DESCRIPTION

The principles described herein have application in any application that requires scanning, and in particular, line scanning. Light or laser detection and ranging, i.e. LIDAR or LADAR, and other hyperspectral applications may implement the wave scanning optic described herein. Various industrial and consumer products may implement the wave scanning optic described herein, such as laser beam scanners used in laser printers, laser bar code readers, etc. Still many other applications may be suitable.

Referring first toFIG.1, a wave scanning optic20according to an exemplary embodiment of the present disclosure is shown. The wave scanning optic20includes a rotatable body22that defines a central axis of rotation24about which the rotatable body22rotates during scanning. The rotatable body22may be formed as a flat disc-shaped body having a surface26. The wave scanning optic20may be rotated by a motor or any other suitable drive mechanism during the scanning operation.

An optical surface28is formed on the rotatable body22opposite the surface26and is formed of a plurality of scanned reflective or refractive optical surfaces. For example, in exemplary embodiments, the wave scanning optic20may be a reflective element or mirror, and in other embodiments, the wave scanning optic20may be a refractive element or lens. The optical surface28has a wavy pattern defined by one or more curved surfaces or lobes30,32that protrude outwardly from the rotatable body22. For example, the lobes30,32may protrude in a direction that is normal to the surface26and parallel with the central axis of rotation24. Any number of lobes30,32may be provided, such as one or more lobes30,32.FIG.1shows an exemplary embodiment in which the optical surface28includes four lobes30,32, but fewer than four or more than four lobes may be provided to achieve a desired scanning operation.

The surface26may be planar or in other exemplary embodiments, the surface26may also have a wavy pattern that is the same or different as compared with the pattern of the optical surface28. If the wave scanning optic20is configured to be a refractive element, then both the optical surface28and the surface26may be wavy to produce a desired scanning pattern as light passes through the wave scanning optic20functioning as a lens. In other exemplary embodiments in which the wave scanning optic20is configured to be a mirror, both the wavy optical surface28and the surface26may be configured to emit and/or receive light.

Each lobe30,32has a height that extends from a valley34, i.e. a shallowest point of the optical surface28, to a peak36of the lobe30,32, a highest point of the optical surface28, such that the optical surface28has a periodic pattern with periods defined by the arcuate distance between the peaks36of the lobes30,32. The peak36may extend as a ridge in the radial direction. In other exemplary embodiments, the optical surface28may have an aperiodic pattern. The height of the peaks36, or amplitude, and the distances between the peaks36and valleys34are formed to provide a certain scan angle. The peaks36and valleys34may be formed to be farther away from each other to provide different scan angles. The amplitudes may also be changed to provide different scan angles. The lobes30,32may have a same shape or a varying shape as required for a particular scanning operation. In exemplary embodiments, the lobes30,32may be equidistantly spaced. In other exemplary embodiments, the spacing between the lobes30,32may be varied.

The optical surface28is a single and continuous 360-degree surface that is configured to provide uninterrupted scanning as the rotatable body22is rotated about the central axis of rotation24. The continuous surface is formed to have a freeform shape, such that the surface is curved and smooth without sharp points or sharply angled surfaces. The wave scanning optic20may have a flat washer-type shape with a radial aperture38arranged about the central axis of rotation24. The shape of the wave scanning optic20may be symmetrical or non-symmetrical. Advantageously, the wave scanning optic20is formed as a single and compact optical component that is able to both emit and receive light.

The radial aperture38may have any suitable dimensions. In an exemplary embodiment, the radial width w of the rotatable body22from the radial aperture38to an outer perimeter40of the rotatable body22may be greater than a diameter of the radial aperture38. Many other dimensions may be suitable. The wave scanning optic may be formed of any suitable materials and any suitable manufacturing method. The substrate or rotatable body22may be formed using additive manufacturing or any other suitable process. The optical surface28may be formed on the rotatable body22using diamond turning and diamond polishing, or any other suitable process.

Referring in addition toFIGS.2and3, the wavy pattern of the optical surface28is a sinusoidal pattern with an angular frequency that varies along the radial width w of the optical surface28from the central axis of rotation24. The angular frequency corresponds to the number of lobes30,32. The pattern of the optical surface28is formed to produce a uniform line scan.FIG.2shows a top view of the optical surface28andFIG.3shows the pattern of the optical surface28being defined by a circular sine wave42. As shown inFIG.3, the surface slope sine wavelength, i.e. the angular wavelength λafor the optical surface28is a function of the radius r of the radial aperture38such that the rotational angular frequency for the wave scanning optic acts as a constant with the radius r of the radial aperture38. The wave scanning optic20may be reflective over all wavelength ranges. The angular wavelength λais equivalent to the angular frequency ω multiplied by the radius r. By way of the sinusoidal pattern of the optical surface28, a line image44of the wave scanning optic20will have a same angle of reflection along its length, and will remain linear over the scan.

Referring now toFIGS.4and5, operation of the wave scanning optic20is shown. By way of the wavy pattern of the optical surface28, the wave scanning optic20is configured to emit and/or receive light in one or more incident directions. In exemplary embodiments, the optical surface28may be configured to emit and/or receive light over multiple paths simultaneously. The one or more incident directions correspond to points of impact46,48,50,52of light that is emitted and/or received on the optical surface28during rotation of the rotatable body22about the central axis of rotation24.

The points of impact46,48,50,52may be formed on each of the lobes30,32. The radial length of the peak36of the corresponding lobe30,32may define a spoke of the wave scanning optic20that extends from the aperture38to the outer perimeter of the rotatable body22. In the exemplary embodiment shown inFIG.4, a first lobe30may have one or more points of impact46,48that are formed along the spoke defined by the first lobe30and a second lobe32may have one or more points of impact50,52formed along the spoke defined by the second lobe32. The points of impact for a single lobe, such as the points of impact46,48for the first lobe50and the points of impact50,52for the second lobe32may be formed along a same radial axis extending from the central axis of rotation24. Points of impact along any spoke of the radial distance relative to the central axis of rotation24may be configured to provide a same scanning angle. Each of the points of impact46,48,50,52is configured to emit and/or receive light in multiple directions D1, D2, D3. The light may be emitted and/or received over multiple paths simultaneously.

FIG.4shows a first scanning region54in which the points of impact46,48receive light from an emitter56and reflect or emit light in three different directions D1, D2, D3. The directions D1, D2, D3correspond to the same point of impact46. Three different directions correspond to the point of impact48. At each point of impact46,48, the light may be emitted in fewer than three directions or more than three directions. Accordingly, as the wave scanning optic20rotates around the central axis of rotation24, or spins, the angular reflectance or refraction at the points of impact46,48are able to produce a uniform line scan, without breaks in the scan pattern. As also shown inFIG.4, the optical surface28may simultaneously receive light from a second scanning region58at the points of impact50,52in multiple different directions. Each of the points of impact50,52may emit the light to a receiver59. Thus, the wave scanning optic20may be used as a receiver and/or an emitter.

FIG.5shows exemplary angles for the scanning or incident directions D1, D2, D3for the optical surface28. For example, D1may correspond to a horizontal scan angle. D2may correspond to a vertical scan angle that is 90 degrees relative to the horizontal scan angle, and D3may correspond to a diagonal scan that is between the horizontal scan angle and the vertical scan angle, i.e. between zero and 90 degrees. The scan angles may correspond to the scanning or incident directions D1, D2, D3for the light emitted from the points of impact46,48to the first scanning region54shown inFIG.4.FIG.5also shows the receiving path R1for light received at the points of impact50,52, such as from the second scanning region58. If the wave scanning optic20has a wavy pattern on both surfaces26,28, light may be emitted and/or received in different directions.

The wave scanning optic20described herein is advantageous as compared with conventional mirrors that include polygonal shapes or facets. In contrast to the conventional mirrors, the wave scanning optic20provides the same scanning angles in the radial direction relative to the central axis of rotation24such that the wave scanning optic20provides continuous multidirectional scanning with uniform lines. This configuration eliminates possible pyramidal errors or facet angle errors that are caused by different angles between facets around the scan in a polygonal or faceted mirror.

Still another advantage of the wave scanning optic20is that the wave scanning optic20is formed as a compact, single optical structure that may be rotated at high speeds without breaks in the scan pattern. In contrast, conventional mirrors require a reset period between scanning periods caused by rotating the optic back to a start point or during a change of direction of the optic during a multidirectional scan. The speed of the scan may be increased by either increasing the speed of rotation of the wave scanning optic20, or by increasing the number of lobes30,32formed on the optical surface28. Accordingly, a desired scan rate for a particular application may be achieved based on the formation of the optical surface28.

FIG.6shows an exemplary application in which the wave scanning optic20is implemented in a LIDAR or LADAR system60for a target62, such as for airborne laser scanning. The LIDAR/LADAR system60may be used to illuminate the target62with a laser light and measure the reflected light with a sensor. The target62may be dependent on the application. The LIDAR/LADAR system60may include any suitable power supply unit64, a controller unit66, a range finding unit68, and a beam deflection unit70including the wave scanning optic20. A function for the power supply unit64includes supplying power to any suitable motor72having a shaft that is coupled to the wave scanning optic20for rotating the wave scanning optic20. The wave scanning optic20may be rotated continuously during operation of the LIDAR/LADAR system60.

In exemplary applications, the LIDAR/LADAR system60may include a laser light source or designator74configured to designate the target62. The designator74and other components of the LIDAR/LADAR system60may be arranged on any suitable platform, such as an aircraft, ground vehicle, naval vessel, or stationary platform. The light source is used to direct light at the wave scanning optic20which reflects the light. Using the wave scanning optic20is advantageous in tracking the path of the designator74, e.g. via simultaneously emitting and receiving light, such that the wave scanning optic20may collect light with a lower power source. In addition to the wave scanning optic20, the beam deflection unit70may include any other suitable optical components, such as additional mirrors, transmissive elements including lenses or filters, beam splitters, manipulators, collimators, focusing elements, or expanders.

Using the wave scanning optic20in the LIDAR/LADAR system60is advantageous in that laser energy may be scanned over a large area. Multiple light paths can use the same optical component, i.e. the wave scanning optic20. Fast multidirectional scanning is also enabled which is particularly advantageous for a LIDAR/LADAR system60which may require faster scanning as compared with other applications. Other hyperspectral line scanning applications and many other applications may also implement the wave scanning optic20.

FIG.7shows another exemplary embodiment of the wave scanning optic20′ in accordance with the present disclosure in which the wave scanning optic20′ has a thickness that is less than the thickness of the wave scanning optic20′ ofFIG.1. The wave scanning optic20′ has lobes76formed on the optical surface28′ that are flatter as compared with the lobes30,32of the wave scanning optic20. For example, a height between the peak78and valley80of the lobe76may be less than that of the height of the lobes30,32of the wave scanning optic20, such that the wave scanning optic20′ has an amplitude that is less than an amplitude of the wave scanning optic20.

The wave scanning optic20′ is shown as having four lobes76, but more than four lobes76or fewer than four lobes76may be provided. Although both wave scanning optics20,20′ have the same number of lobes, the scan angles provided by the wave scanning optic20′ will be different than the scan angles provided by the wave scanning optic20due to the lower amplitude of the lobes76of the wave scanning optic20′ as compared with the lobes30,32of the wave scanning optic20. The flatter lobes76for the wave scanning optic20′ may be advantageous in providing more control of the scanning operation.

FIGS.8and9shows still another exemplary embodiment of the wave scanning optic20″ in which the wave scanning optic20″ is cylindrical in shape as compared with the disc-shaped wave scanning optics20,20′. The wave scanning optic20″ is rotatable about a central axis of rotation82and includes an optical surface28″ that includes one or more lobes84.FIGS.8and9show the optical surface28having three lobes84but fewer than three lobes or more than three lobes may be provided. The optical surface28″ forms a continuous and closed surface that surrounds the central axis of rotation82.

A width w of the optical surface28″ extends parallel with the central axis of rotation82. The width w may be constant along the entire perimeter of the wave scanning optic20″ around the central axis of rotation82and a radial distance between the central axis of rotation82and points along the optical surface28″ varies along the optical surface28″. The optical surface28″ of the wave scanning optic20″ may be advantageous in providing a bi-directional scan and a higher intensity scanning beam.

As shown inFIG.8, the optical surface28″ may be configured to receive an input beam86that is divergent in a horizontal direction. The optical surface28″ may be configured to provide an incident beam that is a line in an x-direction and divergent in a y-direction. As shown inFIG.9, the incident beam88may be collimated in a vertical direction and divergent in a direction that is normal to the rotational plane of the wave scanning optic20″ about the central axis of rotation82. During a constant rotation of the wave scanning optic20″, the optical surface28″ may be configured to provide a range of repeating bi-directional scan line beams from a beam that is incident on the optical surface28″.

Referring now toFIG.10, a method90of scanning is shown. The method90may include using the wave scanning optic20,20′,20″ shown inFIGS.1-9. Step92of the method90includes rotating the wave scanning optic20,20′,20″ about a central axis of rotation24. The wave scanning optic20,20′,20″ has an optical surface28,28′,28″ formed thereon that has a wavy pattern with one or more lobes that protrude outwardly from the optical surface28,28′,28″. Step92of the method90may include providing a uniform line scan during rotation of the wave scanning optic20,20′,20″ via an angular reflectance or refraction of the optical surface28,28′,28″.

Step94of the method90includes emitting and/or receiving light in multiple incident directions. Step96of the method90may include increasing a scan rate of the wave scanning optic20,20′,20″ by either increasing a speed of rotation of the wave scanning optic20,20′,20″ or by increasing a number of the lobes. Step98of the method90includes emitting and/or receiving light over multiple paths simultaneously.