Projection on multiple planes using a single projection unit

Described examples include an optical device having a first light source configured to provide a first light having a first characteristic. The optical device also has a second light source configured to provide a second light having a second characteristic. The optical device also has a combiner configured to combine the first light and the second light to provide a combined light. The optical device also has a spatial light modulator configured to modulate the combined light to provide modulated combined light. The optical device also has a divider configured to receive the modulated combined light and to direct a first portion of the modulated combined light having the first characteristic to a first target and to direct a second portion of the modulated combined light having the second characteristic to a second target.

TECHNICAL FIELD

This relates generally to projection devices and, in examples, to projection devices using spatial light modulation.

BACKGROUND

A wide variety of applications use projection devices. Projection of a video image is the most common application. Other applications include heads-up displays and advertising displays. Another application is recognition and ranging devices. For example, in facial recognition, a projector may project a known pattern onto a face for recognition. A camera or other sensor detects the reflection of the pattern off the face. The data from the camera is processed to determine if the face matches a face in a database. In many cases, an installation may include more than one projection-based technology. This requires a projector for each technology employed. Using multiple projectors adds cost and size to the installation.

SUMMARY

In accordance with an example, an optical device includes a first light source having a first light source output, wherein the first light source is configured to provide a first light having a first characteristic. The optical device also includes a second light source having a second light source output, wherein the second light source is configured to provide a second light having a second characteristic. The optical device also includes a combiner having a first input optically coupled to the first light source output, a second input optically coupled to the second light source output, and a combiner output, wherein the combiner is configured to combine the first light and the second light to provide a combined light on the combiner output. The optical device also includes a spatial light modulator having a spatial light modulator input optically coupled to the combiner output and having a modulated output, wherein the spatial light modulator is configured to modulate the combined light to provide modulated combined light on the modulated output. The optical device also includes a divider having a divider input optically coupled to the modulated output, wherein the divider is configured to direct a first portion of the modulated combined light having the first characteristic in a first direction and to direct a second portion of the modulated combined light having the second characteristic in a second direction.

DETAILED DESCRIPTION

Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are not necessarily drawn to scale.

The term “coupled” may include connections made with intervening elements, and additional elements and various connections may exist between any elements that are “coupled.” Elements referred to herein as “optically coupled” are elements that include a connection between the elements that involves transmission of light. Also, as used herein, the terms “on” and “over” may include layers or other elements where intervening or additional elements are between an element and the element that it is “on” or “over.” Also, as used herein, a “combiner” is a device that combines two or more streams of light into one combined stream of light. Also, as used herein, a “divider” is a device that separates a stream of light stream into two or more streams of light.

In example arrangements, the problem of projecting onto two planes or targets is solved by using a divider at an output of a projection system to use one projection system to project onto two different planes or targets. Examples include an optical device having a first light source having a first light source output, wherein the first light source is configured to provide a first light having a first characteristic. The optical device includes a second light source having a second light source output that is configured to provide a second light having a second characteristic. The optical device has a combiner having a first input optically coupled to the first light source output, a second input optically coupled to the second light source output, wherein the combiner is configured to combine the first light and the second light to provide a combined light on a combiner output. The optical device includes a spatial light modulator having a spatial light modulator input optically coupled to the combiner output, wherein the spatial light modulator is configured to modulate the combined light to provide modulated combined light on a modulated output. The optical device also has a divider having a divider input optically coupled to the modulated output, wherein the divider is configured to direct a first portion of the modulated combined light having the first characteristic in a first direction and to direct a second portion of the modulated combined light having the second characteristic in a second direction.

FIG. 1is a diagram of an example system100for display and identification. Projection unit102includes an optical device for projection of light. In one direction, Projection unit102projects visible light106onto a display target, such as screen108. In this example, the display provided by visible light106onto screen108provides information such as instructions and error messages. Projection unit102also projects non-visible light, such as infrared light110onto a sensing target, such as user104. In an example, infrared light110includes a pattern. Infrared light110reflects off the user104. In other examples, light106and light110may be different colors of visible light. In other examples, light106and light110may differ by other characteristics such as polarization or phase. Sensor(s) (not shown) receive the reflected light of infrared light110. A processor (not shown) in projection unit102analyzes the data from the sensor(s) to determine a biometric measurement and determine if the data matches stored biometric measurements of authorized users. Some arrangements use separate optical devices or engines to produce visible light106and infrared light110. However, such arrangements have the expense of two or more optical engines and may be difficult to calibrate because of the two image sources.

FIG. 2is a diagram of an example optical device200for producing two light streams or images. Infrared light source202produces infrared light204. Green light source206produces green light208. Green light208reflects off combiner210, which serves as a first input of combiner210. Combiner210passes infrared light204, which serves as a second input of combiner210. In this example, combiner210is a dichroic mirror angled at 45° relative to the path of green light208. Thus, green light208reflects off combiner210onto the same path as infrared light204to produce combined light212, which serves as an output for combiner210. Blue light source214produces blue light216. Combiner218combines blue light216and combined light212to produce combined light220. In this example, combiner218is also a dichroic mirror. Red light source222produces red light224. Combiner226combines red light224and combined light220to produce combined light228. In this example, combiner226is also a dichroic mirror. Thus, combined light228includes red, green, blue and/or infrared light, depending on which of light sources202,206,214and222is on. As further explained hereinbelow, by controlling the timing of when infrared light source202, green light source206, blue light source214and read light source222are on or off, combined light228may include any combination of infrared light204, green light208, blue light216and/or red light224. In this example, infrared light source202, green light source206, blue light source214and red light source222are light emitting diodes. In other examples, any or all of these light sources may be laser diodes, high-intensity incandescent light bulbs or other sources of light. In addition, in other examples, other types of combiners can be used, such as X-cubes.

Light integrator230integrates combined light228. In this example, light integrator230is a fly's eye array. Lens (es)232and238, along with the light integrator230and mirror236, provide light234to uniformly illuminate the spatial light modulator240. Light234reflects off one surface of prism242by total internal reflection (TIR), which serves as a spatial light modulator input. In this example, spatial light modulator240is a digital micromirror device. In other examples, spatial light modulator240may be another type of spatial light modulator, such a liquid-crystal on silicon (LCOS) device. Spatial light modulator240modulates light234to provide modulated light244, which is a spatial light modulator output. Because modulated light244addresses the surfaces of prism242and cover prism246at an angle too great for TIR, modulated light244passes through prism242and cover prism246to mirror252.

Projection optics250and mirror252focus modulated light244as projected light253. In this example, mirror252is concaved, and thus has an optical power. In other examples, mirror252may be flat, convex or omitted. In the present example, the concave surface of mirror252allows for a more compact optical device200. In this example, dichroic mirror254reflects light in a selected frequency band, such as infrared light and passes light in other frequency bands, such as visible light. Therefore, projected infrared light256reflects off dichroic mirror254in a first direction. Projected infrared light256is similar to infrared light110(FIG. 1). With the infrared portion of modulated light244removed, visible projected light258passes through dichroic mirror254in a second direction. Visible projected light258is similar to visible light106(FIG. 1). Dichroic mirror254thus functions as a divider with projected light253as an input.

FIG. 3is a diagram of another example optical device300for producing two light streams or images. Infrared light source302is similar to infrared light source202(FIG. 2). Infrared light304is similar to infrared light204(FIG. 2). Green light source306is similar to green light source206(FIG. 2). Green light308is similar to green light208(FIG. 2). Combiner310is similar to combiner210(FIG. 2). Combined light312is similar to combined light212(FIG. 2). Blue light source314is similar to blue light source214(FIG. 2). Blue light316is similar to blue light216(FIG. 2). Combiner318is similar to combiner218(FIG. 2). Combined light320is similar to combined light220(FIG. 2). Red light source322is similar to red light source222(FIG. 2). Red light324is similar to red light224(FIG. 2). Combiner326is similar to combiner226(FIG. 2). Combined light328is similar to combined light228(FIG. 2). Thus, combined light328includes red, green, blue and/or infrared light. Light integrator330is similar to light integrator230(FIG. 2). Lens(es)332are similar to lens(es)232(FIG. 2). Collimated light334is similar to collimated light234(FIG. 2). Mirror336is similar to mirror236(FIG. 2). Lens(es)338are similar to lens(es)238(FIG. 2). Spatial light modulator340is similar to spatial light modulator240(FIG. 2). Prism342is similar to prism242(FIG. 2). Modulated light344is similar to modulated light244(FIG. 2). Cover prism346is similar to cover prism246(FIG. 2). Projection optics350is similar to projection optics250(FIG. 2). Mirror352is similar to mirror252(FIG. 2).

In this example, dichroic mirror354is similar to dichroic mirror254(FIG. 2) in that dichroic mirror354reflects infrared light and passes other light. Therefore, modulated infrared light356reflects off dichroic mirror354. However, in this example, dichroic mirror354is movable. Thus, moving dichroic mirror354changes the direction of modulated infrared light356. This allows for scanning with modulated infrared light356. For example, in some face recognition schemes, a pattern scans across the user's face to enhance recognition capabilities. In the example ofFIG. 3, dichroic mirror354rotates about an axle360, and thus scans in a direction vertical to the page. In other examples, different mechanical configurations are employed to move dichroic mirror354. Modulated infrared light356is similar to infrared light110(FIG. 1). With the infrared portion of modulated light344removed, visible modulated light358passes through dichroic mirror354. Visible modulated light358is similar to visible light106(FIG. 1).

FIG. 4is a conceptual diagram showing schematically the operation of optical device200(FIG. 2) and optical device300(FIG. 3). System400includes optical device402. Light source404can provide infrared, red, green and blue light. Optics406provides uniform light to illuminate spatial light modulator408. Spatial light modulator408modulates the light, as is further described regardingFIG. 5hereinbelow, from optics406to produce an image420including a pattern418of infrared light. Projection optics410projects the modulated image from spatial light modulator408. A divider412such as a dichroic mirror divides the modulated light into infrared light414to pattern418and visible light416(red, green and blue, and combinations thereof) to image420. In other examples, divider412may divide the light according to other characteristics.

FIG. 5is a timeline further describing the operation of optical device402(FIG. 4). During red time period502, light source404(FIG. 4) provides red light. During red time period502, spatial light modulator408(FIG. 4) modulates each pixel so that each pixel of image420(FIG. 4) receives the intensity of red for the color and intensity of that pixel in image420(FIG. 4). During green time period504, spatial light modulator408(FIG. 4) provides the intensity of green. During blue time period506, spatial light modulator408(FIG. 4) provides the intensity of blue. The eye integrates the red, green and blue to the desired color and intensity for each pixel, and thus optical device402produces the desired image420(FIG. 4). During infrared time508, light source404provides infrared light. During this time, spatial light modulator408(FIG. 4) modulates the infrared light to provide the desired intensity and pattern418(FIG. 4). In this example, pattern418(FIG. 4) is for facial recognition.

FIG. 6is a diagram of an example facial recognition system600. Projection system602includes a projector configured to provide to light streams or images using one optical device such as optical device200(FIG. 2) or optical device300(FIG. 3). A short throw projection606from projection system602produces an image on screen604. In this example, the images produced include visual cues to position the user's face, instructions and other messages from an access control system. Infrared projection610projects structured light (SL) patterns608onto the face of user612. Sensors614receive reflections of SL patterns608, which projection system processes to determine biometric measurements of the user612, such as retinal patterns, and compare the biometric measurements to a database to determine if user612is authorized for access.

FIG. 7is a diagram of an example gesture recognition system700. Projection system702includes a projector configured to provide to light streams or images using one optical device such as optical device200(FIG. 2) or optical device300(FIG. 3). A short throw projection from projection system702produces an image706on screen704. In this example, the images produced include locked or unlocked symbols, instructions and other messages from an access control system. Infrared projection710projects a field of patterns708through which user712gestures in a predetermined manner. Sensors714receive reflections of the patterns708that are processed to determine if the appropriated gesture was used and/or a determination of biometric measurements of user712, such as hand size or shape. This information is processed to determine if user712is authorized for access.

FIG. 8is a diagram of an example arrangement800using an optical device such as optical device200(FIG. 2) or optical device300(FIG. 3). In arrangement800, the optical device is in rearview mirror802. Visible light806projects head-up image810onto windshield812. Head-up image810can provide information such as navigation directions, weather, or operational data for the automobile. Infrared light804projects onto the face of driver808. Sensors (not shown) in the dashboard detect reflections of infrared light804off driver808. This information is used to determine if the driver's808eyes leave the road, indicating distracted or drowsy driving, and then a warning can be issued to the driver808. Using an optical device such as optical device200(FIG. 2) or optical device300(FIG. 3) in arrangement800allows for a compact and economical arrangement as opposed to the use of separate projection devices to produce infrared light804and visible light806.

FIG. 9is a diagram of an example health monitoring device900. The user stands on weight measurement platform902, which determines the user's weight. Head unit904includes infrared sensors906, RGB camera908and projector910. Projector910is similar to optical device200(FIG. 2) or optical device300(FIG. 3) where the infrared signal projects onto the user. Visible light from projector910projects onto a screen (not shown) to provide instructions and results. Optical device300(FIG. 3) is particularly suitable for this application because it allows scanning of the infrared signal over the full body of the user. Using the user's body shape and posture allows for determining some medical conditions and indications of potential medical issues.

FIG. 10is a diagram of an example virtual reality game1000. Projector1002includes an optical device such as optical device300(FIG. 3). Projector1002projects visible light1006onto screen1008. Visible light1006projects a scene in which the user plays the virtual reality game. In the example ofFIG. 10, user1004is playing tennis. User1004may play with an actual tennis racquet or a controller. Projector1002projects non-visible light1010onto user1004. In this example, non-visible light1010is infrared light. Projector1002scans the user1004with patterns allowing for rapid determination of the position of user1004. Sensors1014sense the portion of non-visible light1010reflected off user1004and determine the position of user1004many times a second. The sensors1014may or may not be located with projector1002. Because the same spatial light modulator modulates both the visible light1006and non-visible light1010and because projector1002knows the projector settings, calibration between the image on screen1008and user1004is greatly simplified. This allows projector1002to more quickly determine the actions of user1004, and thus the course of game play, to provide a more realistic experience.

FIG. 11is a diagram of an example aperture1100. Aperture1100includes a flat doughnut or toroid shaped ring1102surrounding an opening1104. In this example, ring1102is a dichroic material coated on a transparent material, such as glass. In this example, ring1102reflects or stops non-visible light such as non-visible light1010(FIG. 10). On the other hand, visible light such as visible light1006(FIG. 10) passes through ring1102. With this configuration, the aperture for non-visible light is opening1104. Thus, the aperture for non-visible light is small. The opening for visible light is at least the area of ring1102and opening1104. Thus, the aperture for visible light is larger. In the example ofFIG. 10, visible light1006(FIG. 10) projects onto a fixed screen. Thus, the depth of field necessary to project a focused image onto screen1008is small (e.g., a centimeter or two). A larger aperture allows more light but has a shallow depth of field. Because the visible light image in the example ofFIG. 10is on a fixed screen, a shallow depth of field is acceptable. In addition, greater light throughput provided a brighter projected image. Thus, a large aperture works well for visible light such as visible light1006(FIG. 10).

In contrast, the non-visible light, such as non-visible light1010(FIG. 10) projects on user1004(FIG. 10). User1004(FIG. 10) has a physical depth of at least30or so centimeters and is moving. Thus, it is useful to have a greater depth of field for non-visible light1010(FIG. 10) than for visible light1006(FIG. 10). Because opening1104limits the non-visible light, the non-visible light has a smaller aperture, and thus a greater depth of field. Thus, an aperture such as aperture1100provides a different the aperture for each projected image in an example application such as that ofFIG. 10that improves the functionality of each image.

FIG. 12is an example optical device1200using an aperture similar to aperture1100(FIG. 11). Infrared light source1202is similar to infrared light source302(FIG. 3). Infrared light1204is similar to infrared light304(FIG. 3). Green light source1206is similar to green light source306(FIG. 3). Green light1208is similar to green light308(FIG. 3). Combiner1210is similar to combiner310(FIG. 3). Combined light1212is similar to combined light312(FIG. 3). Blue light source1214is similar to blue light source314(FIG. 3). Blue light1216is similar to blue light316(FIG. 3). Combiner1218is similar to combiner318(FIG. 3). Combined light1220is similar to combined light320(FIG. 3). Red light source1222is similar to red light source322(FIG. 3). Red light1224is similar to red light324(FIG. 3). Combiner1226is similar to combiner326(FIG. 3). Combined light1228is similar to combined light328(FIG. 3). Thus, combined light1228includes red, green, blue and/or infrared light. Light integrator1230is similar to light integrator330(FIG. 3). Lens(es)1232are similar to lens(es)332(FIG. 3). Collimated light1234is similar to collimated light334(FIG. 3). Mirror1236is similar to mirror336(FIG. 3). Lens(es)1238are similar to lens(es)338(FIG. 3). Spatial light modulator1240is similar to spatial light modulator340(FIG. 3). Prism1242is similar to prism342(FIG. 3). Modulated light1244is similar to modulated light344(FIG. 3). Cover prism1246is similar to cover prism346(FIG. 3). Mirror1252is similar to mirror352(FIG. 3). Dichroic mirror1254is similar to dichroic mirror354(FIG. 3). Axle1260is similar to axle360(FIG. 3). Modulated infrared light1256is similar to non-visible light1010(FIG. 10). Visible modulated light1258is similar to visible light1006(FIG. 10).

Partial projection optics1250A and partial projection optics1250B are similar to projection optics350(FIG. 3) except that aperture1251is between partial projection optics1250A and partial projection optics1250B. Aperture1251is similar to aperture1100. That is, aperture1251has a smaller aperture for infrared light than for visible light. Therefore, modulated infrared light1256has a greater depth of focus than visible modulated light1258. In addition, visible modulated light1258has greater light throughput than modulated infrared light1256.

FIG. 13is an example optical device1300using an aperture such as aperture1100(FIG. 11). Infrared light source1302is similar to infrared light source302(FIG. 3). Infrared light1304is similar to infrared light304(FIG. 3). Green light source1306is similar to green light source306(FIG. 3). Green light1308is similar to green light308(FIG. 3). Combiner1310is similar to combiner310(FIG. 3). Combined light1312is similar to combined light312(FIG. 3). Blue light source1314is similar to blue light source314(FIG. 3). Blue light1316is similar to blue light316(FIG. 3). Combiner1318is similar to combiner318(FIG. 3). Combined light1320is similar to combined light320(FIG. 3). Red light source1322is similar to red light source322(FIG. 3). Red light1324is similar to red light324(FIG. 3). Combiner1326is similar to combiner326(FIG. 3). Combined light1328is similar to combined light328(FIG. 3). Thus, combined light1328includes red, green, blue and/or infrared light. Light integrator1330is similar to light integrator330(FIG. 3). Lens(es)1332are similar to lens(es)332(FIG. 3). Collimated light1334is similar to collimated light334(FIG. 3). Mirror1336is similar to mirror336(FIG. 3). Lens(es)1338are similar to lens(es)338(FIG. 3). Spatial light modulator1340is similar to spatial light modulator340(FIG. 3). Prism1342is similar to prism342(FIG. 3). Modulated light1344is similar to modulated light344(FIG. 3). Cover prism1346is similar to cover prism346(FIG. 3). Projection optics1350is similar to projection optics350(FIG. 3). Mirror1352is similar to mirror352(FIG. 3). Dichroic mirror1354is similar to dichroic mirror354(FIG. 3). Axle1360is similar to axle360(FIG. 3). Modulated infrared light1356is similar to non-visible light1010(FIG. 10). Visible modulated light1358is similar to visible light1006(FIG. 10).

In optical device1300, aperture1351is between light integrator1330and lens(es)1332. Aperture1351is similar to aperture1100. Like aperture1100and aperture1251, aperture1351has a smaller aperture for infrared light than for visible light. Therefore, modulated infrared light1356has a greater depth of focus than visible modulated light1358. In addition, visible modulated light1358has greater light throughput than modulated infrared light1356.

FIG. 14is a flow diagram of an example process1400. Step1402is producing a first light having a first characteristic. In an example, the first light is similar to infrared light204(FIG. 2). Step1404is producing a second light having a second characteristic. In an example, the second light is similar to green light208, blue light216or red light224(FIG. 2), or a combination thereof. Step1406is combining the first and second light to produces combined light. The combined light is similar to combined light228(FIG. 2). Step1408is modulating the combined light to produce modulated light. A spatial light modulator similar to spatial light modulator240modulates the modulated light in an example to produce modulated light244. Step1410is projecting the modulated light to provide projected light. Projection optics similar to projection optics250projects the modulated light to produce projected light similar to projected light253. Step1412is dividing the projected light into first projected light having the first characteristic and second projected light having the second characteristic, wherein the first projected light is directed in a first direction and the second projected light is directed in a second direction. The first projected light is similar to projected infrared light256. The second projected light is similar to projected light258.