阅读说明：本技术 用于将目标图案投射在人眼的修饰的视网膜区域的方法和装置 (Method and apparatus for projecting a target pattern on a modified retinal region of a human eye ) 是由 B.德班 J-B.弗洛德 M.德纳芙 M.德特瑞 于 2020-03-27 设计创作，主要内容包括：本发明涉及用于将目标图案(6)投射在人眼的修饰的视网膜区域(5)上的方法,其包括以下步骤：提供脉冲输入光束(20),基于目标图案(6)将所述脉冲输入光束(20)调制并划分为调制脉冲子光束(40)的脉冲调制光图案,其中所述调制光图案形成反映所述目标图案(6)的脉冲输出光束(4),其中对形成所述输出光束(4)的调制单个子光束(40)的调制占空比(32)进行单个脉冲宽度调制,以及相应地适配装置。(The invention relates to a method for projecting a target pattern (6) on a modified retinal region (5) of a human eye, comprising the following steps: -providing a pulsed input light beam (20), -modulating and dividing said pulsed input light beam (20) based on a target pattern (6) into a pulsed light pattern of modulated pulsed sub-light beams (40), wherein said modulated light pattern forms a pulsed output light beam (4) reflecting said target pattern (6), wherein the modulation duty cycles (32) of the modulated individual sub-light beams (40) forming said output light beam (4) are individually pulse-width modulated, and-adapting the means accordingly.)

1. A method for projecting a target pattern (6) on a modified retinal region (5) of a human eye, comprising:

-providing a pulsed input light beam (20),

-modulating and dividing the pulsed input light beam (20) into pulsed and modulated light patterns of modulated pulsed sub-light beams (40) based on a target pattern (6), wherein the modulated light patterns form a pulsed output light beam (4) reflecting the target pattern (6),

it is characterized in that

-single pulse width modulating the modulation duty cycle (32) of the modulated single sub-beams (40) forming the output beam (4).

2. The method according to claim 1, wherein the input light beam (20) comprises a constant peak irradiance (23), and/or the input light beam (20) substantially comprises the form of a pulsed wave, and/or the input light beam (20) comprises a constant period (21), and/or the input light beam (20) comprises a constant duty cycle (22) or controls the duty cycle (22) of the input light beam (21).

3. The method according to any of the preceding claims, wherein a modulation period (31) is synchronized with a period (21) of the pulsed input beam (20).

4. The method according to any one of the preceding claims, wherein a maximum individual modulation duty cycle (32) of the individual sub-beams (4) corresponds to a duty cycle (22) of the pulsed input beam (20).

5. The method according to any one of the preceding claims, wherein the duty cycle (22) of the pulsed input beam (20) with respect to the period (21) of the pulsed input beam (20) is equal to or less than 0.5, preferably 0.4, particularly preferably 0.3, and/or the maximum possible modulation duty cycle of the sub-beam (40) with respect to the period (21) of the pulsed input beam (20) is equal to or less than 0.5, preferably 0.4, particularly preferably 0.3.

6. Method according to any of the preceding claims, wherein the target pattern (6) is obtained by capturing visual information, preferably an image, and dividing the captured visual information into a pattern of pixels forming the target pattern (6), wherein the pixels reflect at least different luminance values, if any, within the visual information.

7. An apparatus (1) for projecting a target pattern (6) on a modified retinal region (5) of a human eye, comprising:

a light source (2) for providing a pulsed input light beam (20),

-a modulating micro-mirror array (3) for modulating and dividing the pulsed input light beam (20) into modulated light patterns of modulated pulsed sub-light beams (40), wherein the orientation of each micro-mirror (30) of the micro-mirror array (3) is independently controllable based on a target pattern (6) such that the sub-light beams form a pulsed output light beam (4) reflecting the target pattern (6),

it is characterized in that

The device (1) is formed and adapted to perform a single pulse width modulation of sub-beams (40) forming said output light beam (4) by independently controlling modulation duty cycles (32) of individual micro-mirrors (30).

8. The device (1) according to the preceding claim, further adapted to synchronize a modulation period (31) of the orientation control of the micro-mirrors (30) with a period (21) of the pulsed input light beam (20).

9. The apparatus of any of claims 7 or 8, wherein a maximum single modulation duty cycle (32) of the micro-mirror (30) corresponds to a duty cycle (22) of the pulsed input light beam (20).

10. The apparatus (1) according to any one of claims 7 to 9, wherein a duty cycle (22) of the pulsed input beam (20) with respect to a period (21) of the pulsed input beam (20) is equal to or less than 0.5, preferably 0.4, particularly preferably 0.3, and/or a maximum possible modulation duty cycle (32) of the sub-beam (40) with respect to the period (21) of the pulsed input beam (20) is equal to or less than 0.5, preferably 0.4, particularly preferably 0.3.

11. The device (1) according to any one of the preceding claims, further comprising a camera for capturing visual information, preferably an image, and/or a processing unit for dividing the captured visual information into a pattern of pixels forming the target pattern (6), wherein the pixels reflect at least different luminance values, if any, within the visual information.

Technical Field

The present invention relates to a method for projecting a target pattern onto a region of the human retina that has been modified to restore its photosensitive properties, for example by implantation of a retinal implant, and to a corresponding device.

Background

Retinal dysfunction, particularly caused by degenerative retinal diseases, is a major cause of impaired vision and even blindness.

In order to restore at least partially the visual function of a patient, it is known to exploit modifications of the retinal area of the human eye, for example by using retinal implants or in other words retinal prostheses. In this respect, several different types of retinal implants are known, which are based on different working principles.

Common to retinal implants is that they are typically placed in the patient's eye under the retina, on the retina or on the choroid so that they can effectively replace damaged photoreceptors. In this regard, information about the visual scene is captured with a camera and then transmitted to an electrode array implanted in the retina.

Among the common retinal implants, implants are known that comprise a wire (wire) that penetrates the skin. These wires carry the risk of infection and scarring. Therefore, more modern implants use different wireless technologies, such as power and visual information delivered by an induction coil. Furthermore, it is known to transfer power inductively and visual information optically through the pupil of the eye, or to transfer visual information and power optically.

A particularly advantageous wireless information transmission to the retinal implant is based on projecting a stimulus pattern, preferably infrared light, into the eye. When the gaze direction is such that certain portions of the implant are illuminated by a partial pattern, the implant converts that partial signal into an electrical current, thereby stimulating the retina accordingly.

Retinal implants are arrays of stimulating electrodes or pixels. Each pixel has one or several photodiodes that capture the light emitted by the vision processor and convert it into electrical current for stimulation.

Several implant arrays may be placed in the subretinal space, typically at or near the foveal region.

Alternatively, a method known as optogenetics has been proposed to treat the remaining retinal cells to restore their photosensitizing behavior by gene therapy. Optogenetics refers to the combination of genetics and optics to control well-defined events within specific cells of living tissue. Optogenetics involves (i) genetically modifying target cells to make them sensitive to light by expressing exogenous photoreactive proteins in the cell membrane, and (ii) providing a lighting device capable of providing light to the photoreactive proteins.

In the following paragraphs of this patent, such retinal regions of the human eye that have been modified to restore light-sensitive behavior by implantation of a retinal prosthesis or by modification by optogenetics will also be referred to as "modified retinal regions".

In order to project light or light beams, respectively, into the human eye, it is known to use projector devices, such as augmented reality goggles. A projector unit of the projector device, e.g. a projector optics, projects a pulsed light beam onto and at least partially into the human eye. That is, the picture to be transmitted is transmitted into the eye through the pupil of the eye and towards the retina.

Although the patient may thereby be provided with a target illumination pattern, the patient is only able to perceive a single bright-dark contrast, since the illumination is constant for each pulse of the pulsed light beam.

However, safety issues are associated with the use of such projector devices. For example, the projector apparatus and method of use must ensure that the illumination on the retina conforms to a particular duty cycle, e.g., less than 0.5, may be required to ensure proper safety of the modified retinal area, e.g., the retinal implant, e.g., to ensure proper electrical discharge between the implanted pulsed electrical function and the electrical pulses.

Similarly, for optical safety, it may also be desirable that the projector apparatus and method of use must ensure that the illumination on the retina conforms to a duty cycle, thereby ensuring that the average light irradiance does not reach a safe threshold. Thus, if the modulation is performed with a sufficiently low duty cycle, high light irradiance may be acceptable. This may be achieved by providing a command to the light source to periodically turn off between pulses of a particular duty cycle. It can also be achieved by ensuring that the micromirror is turned off regularly between pulses of a certain duty cycle. However, for medical applications, it is often required that safety and associated duty cycle should be ensured even under a single fault condition.

Disclosure of Invention

It is an object of the present invention to provide an improved method for projecting a target pattern on a modified retinal area of a human eye, and a corresponding apparatus for projecting a target pattern on the modified retinal area.

The above object is solved by a method for projecting a target pattern on a modified retinal region of a human eye comprising the features of claim 1. Further preferred embodiments are presented in the dependent claims, the description and the drawings.

Accordingly, in a first aspect, a method for projecting a target pattern on a modified retinal region of a human eye or a method of operating an apparatus for projecting a target pattern as described herein is presented, comprising the steps of: providing a pulsed input light beam, preferably comprising coherent light or incoherent light and/or light preferably having a wavelength in the near-infrared field, and modulating and dividing the pulsed input light beam based on a target pattern into a pulsed and modulated light pattern of modulated pulsed sub-beams, wherein the modulated light pattern forms a pulsed output light beam reflecting the target pattern. The method is characterized by the step of single pulse width modulating the modulation duty cycle of the modulated single sub-beams forming the output beam.

Since the modulation duty cycle of each sub-beam can be adjusted separately and individually, the illumination duration of each sub-beam can be controlled separately by a single pulse width modulation of the single sub-beam. That is, for each cycle of the pulsed output beam, the duration of illumination at the retinal implant at which the output beam is directed may vary within the output beam, as each sub-beam may comprise a single duty cycle. Thus, the photodiodes of the retinal implant may be exposed to different illumination durations, which in turn result in different stimulation currents and/or different retinal stimulation durations. Thereby, a grey scale perception of the projected pattern illuminated via the output light beam may be achieved. In other words, it is therefore possible to illuminate the retina with a pattern that is converted to a different perceived grey level within one pulse period. Thus, a patient equipped with a corresponding light-sensitive retinal implant may be able to sense or perceive an at least substantial grayscale image. The latter may improve or promote orientation of the patient and may increase visual ability.

The target pattern here may be based on a picture or image that is captured and to be projected, wherein the picture or image may comprise dark and bright areas, preferably comprising pixels of different luminance values.

Preferably, the modified retinal region may be provided via implantation of a retinal prosthesis.

According to a further exemplary embodiment, the input light beam comprises a constant peak irradiance. Thereby, the irradiance hitting (hit) the retinal implant can be accurately identified, determined and/or calculated. Thus, a reliable operation of the retinal implant and prevention of retinal damage due to unknown excess irradiance may be achieved.

Alternatively or additionally, the input beam may substantially comprise the form of a pulsed wave, as the beam so formed may have the advantage of substantially constant illumination during each duty cycle.

Preferably, the input light beam comprises a constant period.

According to another preferred embodiment, the input light beam comprises a constant duty cycle. Optionally, the duty cycle of the input beam is controlled.

According to yet another preferred embodiment, an optimal adaptation of the grey scale distribution inside the output light beam can be achieved when the modulation period is synchronized with the period of the pulsed input light beam. In other words, the period of the pulse width modulation, and thus the period of the sub-beams, corresponding to the modulation period is synchronized with the period of the pulsed input beam.

According to another preferred embodiment, the method may be optimized in that the maximum individual modulation duty cycle of the individual sub-beams corresponds to the duty cycle of the pulsed input beam.

To prevent damage to the retina due to excessive illumination, the duty cycle of the pulsed input beam may preferably be equal to or less than 0.5, preferably 0.4, particularly preferably 0.3, of the period of the pulsed input beam, and/or the maximum possible duty cycle of the sub-beams may preferably be equal to or less than 0.5, preferably 0.4, particularly preferably 0.3, of the period of the pulsed input beam.

According to another preferred embodiment, the target pattern is obtained by capturing visual information, preferably an image, and dividing the captured visual information, preferably the captured image, into a pattern of pixels forming the target pattern, wherein the pixels reflect at least different luminance values, if any, within the visual information, preferably within the image.

Preferably, the captured image is subjected to optional image processing prior to assigning luminance values to pixels or regions of the processed image.

Furthermore, the above object is solved by a device for projecting a target pattern on a modified retinal area of a human eye, preferably comprising a retinal implant, comprising the features of claim 7. Further preferred embodiments are presented in the dependent claims, the description and the drawings.

Thus, in a second aspect, a device for projecting a target pattern on a modified retinal area of a human eye is presented, comprising a light source for providing a pulsed input light beam, preferably a light beam of preferably coherent or incoherent light, preferably light having a near infrared field wavelength, and a modulated micro mirror array for modulating and dividing the pulsed input light beam into modulated light patterns of modulated pulsed sub-beams, wherein the orientation of each micro mirror of the micro mirror array is independently controllable based on the target pattern such that the sub-beams form a pulsed output light beam reflecting the target pattern. The device is further formed and adapted for single pulse width modulation of the sub-beams forming the output light beam by independently controlling the modulation duty cycles of the individual micromirrors.

By means of which the effects and advantages described for the above-mentioned method can be achieved.

According to a preferred embodiment, the device is further adapted to synchronize the modulation period of the orientation control of the micromirrors with the period of the pulsed input beam.

For synchronization of the modulation by the micromirror array and the input light beam pulses, the maximum individual modulation duty cycle of the micromirrors may preferably correspond to the duty cycle of the pulsed input light beam.

In order to prevent the output light beam from causing damage to the retina, the duty cycle of the pulsed input light beam relative to the period of the pulsed input light beam may preferably be set equal to or less than 0.5, preferably 0.4, particularly preferably 0.3, and/or the maximum possible modulation duty cycle of the sub-light beam relative to the period of the pulsed input light beam may preferably be equal to or less than 0.5, preferably 0.4, particularly preferably 0.3.

According to another preferred embodiment, the apparatus may further comprise a camera for capturing visual information, preferably an image, and/or a processing unit for dividing the captured visual information, preferably the captured image, into a pattern of pixels forming the target pattern, wherein the pixels reflect at least different luminance values, if any, within the visual information, preferably within the image.

Furthermore, it is important to note that for wearable electronic devices such as projector devices, battery life must be as long as possible to ensure the longest run time between battery or power source charges. Thus, for a given reasonable battery size, the power consumption of the device must be minimized. Advantageously, the modulation of the light source proposed according to the invention allows to regularly switch off the power supply between the pulses, thereby significantly reducing its power consumption. Furthermore, the fact that it is operated for only a small fraction of the time cuts (limit) the power consumption needed to cool the laser source, for example by means of a peltier element or a fan operation. Thus, pulsing the laser source at a particular duty cycle can significantly improve battery life.

Drawings

The disclosure will be more readily understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 schematically shows an apparatus for projecting a target pattern onto a light-sensitive modified retinal region of a human eye;

FIG. 2 schematically shows a detailed view of the target pattern of FIG. 1, which is an illuminated area of a modified retinal area;

FIG. 3 schematically shows a pulsed input beam comprising a pulsed wave shape and corresponding modulated pulsed beamlets;

FIG. 4 schematically shows another input light beam having substantially the form of a pulse wave and micromirror pulses corresponding to three different micromirrors, thereby generating three different sub-beams; and

fig. 5 schematically shows an example of a target pattern area projected on a retinal implant via the sub-beams of fig. 5.

Detailed Description

Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings. In the drawings, the same elements are denoted by the same reference numerals and repeated description thereof may be omitted to avoid redundancy.

Fig. 1 schematically shows an apparatus 1 for projecting a target pattern 6 on a modified retinal region 5 of a human eye. The apparatus 1 comprises a light source 2 which provides a pulsed input beam 20, the pulsed input beam 20 comprising light having a wavelength in the near-infrared field.

The input light beam 20 is directed onto a modulating micro-mirror array 3 comprising a plurality of micro-mirrors 30, which micro-mirrors 30 can be operated independently, such that the orientation of each micro-mirror 30 can be adjusted and/or controlled independently. The modulating micromirror array 3 according to this embodiment is provided in the form of a digital micromirror device known per se.

The input light beam 20 is reflected by the micro mirror array 3 to form an output light beam 4. The output light beam 4 is composed of a plurality of sub-beams 40 divided by the time the input light beam 20 hits a single micro-mirror 30 of the micro-mirror array 3. The orientations of the micro-mirrors 30 are adjusted independently such that the target pattern 6 to be projected onto the modified retinal area 5 is reflected by the plurality of sub-beams 40.

In this regard, the target pattern 6 is based on an image captured by a camera (not shown), which has been processed into a digital pattern of pixels, where the pixels comprise grey values corresponding to the brightness values of the respective areas of the image. Such data processing is known per se.

That is, only those micro-mirrors 30 corresponding to pixels comprising a brightness value above a predetermined threshold are controlled to reflect the input light beam 20, wherein the micro-mirrors 30 corresponding to pixels comprising a brightness value below a predetermined threshold are oriented such that they do not contribute to forming the output light beam 4.

Optionally, the modified retinal region 5 may comprise a retinal implant, preferably a light sensitive retinal implant.

Thus, the output beam 4 substantially reflects the target pattern 6. When the output light beam 4 hits the modified retinal area 5, only those parts of the modified retinal area 5 comprising the retinal implant are illuminated by the output light beam 4, or in particular the sub-beams 40, which sub-beams 40 reflect the target pattern at the retinal implant. Thus, only those photodiodes of the retinal implant, which are arranged in the projected target pattern 6, convert light into electrical current. Thus, a person comprising the retinal implant may perceive the target pattern 6.

Fig. 2 schematically shows a detailed view of the target pattern 6, which is the illumination area of the modified retinal area 5.

The input light beam 20 is pulsed into a waveform comprising the shape of a pulse wave, as can be taken from fig. 3. Because the light source 2 comprises constant illumination 23 which is illuminated during each duty cycle 22 in each period 21 of the wave of the light beam 20, the light beam 20 is pulsed by the light source 2.

Thus, since the output light beam 4 is substantially based on the input light beam 20, the output light beam 4 is also pulsed, wherein the period of the output light beam 4 and the duty cycle of the output light beam 4 typically correspond to the period 21 and the duty cycle 22 of the input light beam 20. Thus, the target pattern 6 comprises a uniform illumination over its entire surface, as depicted in fig. 2.

To achieve the ability to also provide grey scale information to the output beam 4, the device 1 is further formed and adapted to pulse width modulate each sub-beam 40 independently. The latter is achieved by independently controlling the modulation duty cycle 32 of each individual micromirror 30.

In other words, each micro-mirror 30 is oriented in a position such that it reflects the input light beam 20 and thereby provides that the time for which the sub-beams 40 contributing to the output light beam 4 are independently set to be different for each micro-mirror 30, depending on the respective grey level of the pixel in the target pattern 6 associated with the respective micro-mirror 30.

In this regard, pulse width modulation is performed such that the modulation duty cycle 32 can be independently adjusted for each micromirror pulse period. That is, as the camera continues to capture images, variations in pixel brightness levels may cause the modulation duty cycle 32 to vary. Thus, as the brightness level increases, the modulation duty cycle 32 also increases accordingly, and vice versa.

Preferably, as shown in FIG. 3, the modulation period 31 of the micromirror pulse 33 corresponding to the output beam period 41 is synchronized with the period 21 of the input beam 20. Further, optionally, the maximum possible modulation duty cycle 32 of the micro-mirrors 30 is set to correspond to the constant duty cycle 22 of the input light beam 20.

Thus, when the light source 2 does not provide irradiance, it can be achieved that the operation of the micromirror 30 is not performed. This may therefore ensure safe operating power of the device 1.

In fig. 3, two subsequent micromirror pulse periods for a single micromirror 30 are shown, and thus, the sub-beams 40 are shown. The first modulation duty cycle 32 shown is less than the second modulation duty cycle 32 'shown, wherein the irradiance 42 is constant for each modulation duty cycle 32, 32'. Thus, a patient including a retinal implant will perceive the corresponding region of the image as becoming brighter.

Furthermore, it can be seen in this figure that both modulation duty cycles 32, 32' are shorter than the duty cycle 22. Thus, the level of brightness perceived by the patient is lower than the maximum possible perceived brightness. For safety reasons, the duty cycle 22 is limited to 30% of the period 21, thereby preventing retinal damage due to excessive illumination.

To provide a redundant safety system, the duty cycle 32 of the micromirror 30 is also limited to 30% of the period 21 or the modulation period 31, respectively. Therefore, in case the light source erroneously emits a constant light beam, the maximum possible duty cycle of the output light beam 4 is limited to the duty cycle 32 of the micro mirror 30.

Thus, even if the safety setting of the light source 2 fails, it is achieved that no excessive irradiance hits the retina. Furthermore, if the micromirror 30 fails to pulse and/or is stuck in the "ON" position, the source pulse inhibits the pulse duration of the output beam 4 from being made higher than the source pulse duration, i.e., higher than the duty cycle 22.

Fig. 4 shows an exemplary embodiment of a waveform of the input light beam 20, which has substantially the form of a pulsed wave, comprising a constant source irradiance 23, a constant duty cycle 22 of pulses 24, and a constant period 21.

Below the waveform of the input light beam 20, the micromirror pulses 33, 33 ', 33 "of three different micromirrors 30 are shown, thereby generating three different sub-beams 40, 40', 40".

The micromirror pulses 33, 33 ', 33 "differ from each other in that the duty cycles 32, 32 ', 32" of their respective pulses 34, 34 ', 34 "are different.

That is, each of the sub-beams 40, 40 ', 40 "has a radiation power different from the other sub-beams, wherein the first sub-beam 40 comprises a lower radiation power than the second and third sub-beams 40 ', 40" and the second sub-beam 40 ' comprises a lower irradiation power than the third sub-beam 40 ".

Thus, for example, when a first region 61 of the target pattern 6 is illuminated by a sub-beam corresponding to sub-beam 40, the patient comprising the retinal implant perceives darker gray values than a second region 62 illuminated by a sub-beam corresponding to sub-beam 40' and a third region 63 illuminated by a sub-beam corresponding to sub-beam 40 ", the latter comprising the brightest gray values.

An example of the above-mentioned zones 61, 62, 63 of the target pattern 6 projected on the modified retinal area 5 comprising the retinal implant can be obtained from fig. 5.

Thus, by means of the above-described device 1 and the corresponding method, a patient may be provided with a light-sensitive retinal implant comprising patterns with different grey levels.

Furthermore, the power consumption for carrying out the method and/or the operation of the device 1 can be reduced and/or optimized by the above, since the light source can be switched off between pulses and thus consume less energy between pulses and thus reduce the power consumption.

It is obvious to a person skilled in the art that these embodiments and items are only examples describing many possibilities. Thus, the embodiments shown herein should not be construed as limiting these features and configurations. Any possible combination and configuration of the features may be selected in accordance with the scope of the invention.

List of reference numerals

1. Device for measuring the position of a moving object

2. Light source

20. Input light beam

21. Period of time

22. Duty cycle

23. Irradiance of

24. Pulse of light

3. Micro mirror array

30. Micro mirror

31. Modulation period

32. Modulation duty cycle

33. Micro mirror pulse

34. Pulse of light

4. Output light beam

40. Sub-beams

41. Output beam period

42. Irradiance of

5. Modified retinal regions

6. Target pattern

61. First region

62. Second region

63. Third zone