Method and device for measuring imaging quality of measured optical system

Abstract

The invention relates to a method for determining the imaging quality of an optical system (102) under test, wherein the method comprises a step of capturing an optical wavefront profile (107) in a measurement plane behind an exit pupil of the optical system (102), a step of determining an optical partial wavefront profile for each of a plurality of sub-apertures of the measurement plane using the wavefront profile (107), and a step of determining an optical split imaging quality for each of the sub-apertures using the determined optical split front profile.

Description

Technical Field

[0001] The invention relates to a method and a device for determining the imaging quality of an optical system to be measured, of the type specified in the independent claims. Background Art

[0002] For applications and systems in the field of augmented reality (AR) and virtual reality (VR), the image quality within the field of view (Eye-Box) (i.e. within the eye movement range) is an important quality parameter. The field of view can be understood as a three-dimensional volume, and the rotation center of the eye must be located in this three-dimensional volume in order to fully perceive the presented image through eye movement or rotation.

[0003] US10 277 893 B1 describes a camera system arranged behind the VR helmet under test. The measurement task is accomplished by mechanical displacement of a measuring device (e.g. a camera) arranged behind the exit pupil of the specimen. The user's eye movements are mechanically reconstructed by the camera system. Summary of the invention

[0004] Against this background, the present invention proposes an improved method and device for determining the imaging quality of an optical system to be measured as described in the independent claims. The device provided in the independent claims can be advantageously further designed and improved by the measures listed in the dependent claims.

[0005] The invention provides a simple and time-saving method for determining the imaging quality of the optical system under test without using, for example, a scanning process or a mechanical grid. The advantage is that multiple measurement parameters can be obtained from one measurement, so that, for example, a low error rate can also be achieved.

[0006] The present invention proposes a method for measuring the imaging quality of an optical system under test, the method comprising the steps of capturing an optical wavefront profile in a measuring plane behind an exit pupil of the optical system, dividing or splitting the measuring plane into a plurality of sub-apertures, measuring an optical sub-wavefront profile for each of the plurality of sub-apertures of the measuring plane using the wavefront profile, and measuring the optical sub-image quality for each sub-aperture using the measured optical sub-wavefront profile, thereby describing the imaging quality distribution on the entire measuring plane.

[0007] The optical system under test can be implemented, for example, as smart glasses, optical devices of smart glasses, or eyeglasses that can be combined with AR / VR devices that are usually worn close to the human eye. The method can advantageously measure and verify the imaging quality of the optical system under test in the field of view. The corresponding measurement results can be used, for example, to verify or improve the optical system. The optical wavefront profile can represent the optical wavefront profile in the measurement plane or the image of the light wave on the measurement plane. Among them, the light wave can propagate from the exit pupil of the optical system in the direction of the measurement plane. The wavefront profile can be affected by the structure of the optical system under test, which can, for example, affect the optical path of the optical system under test. In this way, the imaging quality of the optical system under test can be inferred based on the characteristics of the wavefront profile. The imaging quality can be related to at least one characteristic parameter of the optical transfer function of the optical system under test. The subaperture can be designed, for example, as a segmented surface of the measurement plane, which can together form the measurement plane or a part of the measurement plane located in the field of view. In this case, the subapertures may partially overlap, because, in particular in optical systems for AR / VR, the usually larger exit pupil is generated by multiplying the usually smaller entrance pupil. Therefore, the partial wavefront profiles together (ie as a whole) can form the captured wavefront profile of the measurement plane. In this way, the partial wavefront profiles of the sub-apertures can be determined by dividing the wavefront profile. The sub-aperture can have a diameter of less than 10 mm, for example. 2 The subapertures may be of equal size. The subapertures may be of the order of magnitude of the pupil of the human eye. The sub-image quality may be related to at least one characteristic parameter of the optical transfer function of the optical system under test which may correspond to a portion of the subaperture concerned. Advantageously, the method allows the image quality at each pupil position in the field of view to be determined by a so-called one-shot measurement, which can significantly reduce the time required for the measurement. For example, the image quality of a subaperture in a measurement plane can be used to illustrate the distribution of an image quality parameter over the entire measurement plane.

[0008] As an alternative, the method described here can also be applied to other near-eye optical systems outside the field of virtual reality or augmented reality applications. An example of such a system is a bifocal contact lens or a progressive ophthalmic lens. Such optical components have the characteristic that the exit aperture is divided into different regions, wherein each region can correspond to a different refractive power. Therefore, the imaging quality distribution of such near-eye optical systems can also be determined by the method described here. In this case, the subapertures that can correspond to the regions of different refractive power can have different sizes and do not have to be uniformly distributed on the measurement plane.

[0009] US20210382323 A1 discloses an example of a bifocal contact lens. The lens described in the document has a far vision zone located in the upper lens zone and a near vision zone located in the lower lens zone. The lens also has an outer ring structure that stabilizes the eye when it moves. The near and far zones of the contact lens are utilized by offsetting the contact lens relative to the pupil. According to one embodiment, this can be simulated in a measured manner by differently positioned subapertures.

[0010] According to one embodiment, in the capturing step, a wavefront sensor may be used to capture the wavefront profile in the measurement plane. The wavefront sensor may be implemented, for example, as part of a test device that may be used to implement the method. The wavefront sensor may advantageously capture a light beam penetrating the optical system under test and provide the captured light beam for evaluation. The wavefront sensor may be implemented, for example, as a known Shack-Hartmann sensor.

[0011] A division rule for dividing the measurement plane into a plurality of sub-apertures in the division step can be predetermined for the measurement plane. Advantageously, the division step can be used to easily determine the image quality at different positions within the field of view, wherein the individual sub-apertures can partially overlap. Furthermore, a mechanical rasterization or scanning process of the measurement plane can be omitted.

[0012] Furthermore, the method may comprise the step of determining a measurement volume prior to the capturing step, wherein the measurement plane may represent a cross section of the measurement volume. The size of the measurement volume may be comparable to the size of the used field of view. By determining a measurement volume of suitable size and location, the imaging quality of a portion of the optical system under test that is relevant to the intended subsequent use of the optical system under test may be determined.

[0013] According to one embodiment, the method may further include the step of measuring the quality of other optical component images for each of a plurality of other sub-apertures of other measurement planes behind the exit pupil of the optical system. In this measuring step, the image quality can be further determined using the quality of other component images. The measurement plane and the other measurement planes can advantageously be linearly spaced along the optical axis of the measured optical system. For example, the measured optical system can have a plurality of measurement planes, the distances between which can be achieved, for example, uniform. Advantageously, the quality of other component images can be determined by one measurement. The other measurement planes can consist of a plurality of other sub-apertures (i.e., sub-regions). This means that each other sub-aperture can be formed as a segment of the other measurement planes. Similarly, the other wavefront profiles can consist of a plurality of other sub-wavefront profiles of the other sub-apertures.

[0014] Furthermore, the method may comprise the step of capturing other optical wavefront profiles in other measurement planes and the step of determining other optical partial wavefront profiles for each of a plurality of other subapertures of other measurement planes using the other wavefront profiles. Advantageously, the other wavefront profiles may also be captured using a wavefront sensor.

[0015] As an alternative to the measurement, the wavefront profile of the measurement plane can be used in the calculation step to calculate at least one other wavefront profile in other measurement planes. In addition, other optical partial wavefront profiles can be determined for each of a plurality of other sub-apertures of other measurement planes in the determination step using the other wavefront profiles. This means that the other wavefront profiles can be inferred from already existing data on the wavefront profiles.

[0016] According to one embodiment, in the calculation step, the other wavefront profiles in the second measurement plane can be calculated by a known ray tracing algorithm. A ray tracing algorithm, also known as a beam tracking algorithm, can represent an algorithm for calculating a beam distribution based on a beam emission, which is capable of determining the spatial distribution of a beam starting from a certain point in space. Advantageously, the algorithm can be implemented in advance so that the other wavefront profiles can be calculated, for example, using previously captured and additionally or alternatively measured data related to the optical system under test. As an alternative, the calculation step can be performed on the mathematical basis of a wave optics model.

[0017] According to one embodiment, the size of the plurality of subapertures may be different from the size of the plurality of other subapertures. This means, for example, that there may be a difference in the size of the subaperture and the other subapertures. Furthermore, the measurement plane may be divided between multiple evaluation iterations, and additionally or alternatively, other measurement planes may be divided between multiple evaluation iterations.

[0018] In addition, the present invention proposes a device for measuring the imaging quality of an optical system under test, wherein the device includes a receiving device for receiving the optical system under test, another optical system for capturing the optical wavefront profile in a measuring plane behind an exit pupil of the optical system under test, and an evaluation device, wherein the evaluation device is used to divide the measuring plane into a plurality of sub-apertures, measure an optical sub-wavefront profile for each of the plurality of sub-apertures of the measuring plane using the wavefront profile, and measure the optical sub-image quality for each sub-aperture using the measured optical sub-wavefront profile.

[0019] The device can be implemented as a measuring device, for example, and can be used for the manufacture or testing of optical systems (such as smart glasses or general AR / VR systems). The receiving device can be implemented as a bracket, such as a gripping arm or a holding arm, or simply as a receiving area. Another optical system can be implemented as a sensor unit, such as a wavefront sensor. The evaluation device can also be referred to as a computing unit, which can be connected to another optical system. The device can be advantageously used as an optical measurement technology for, for example, AR / VR helmets, components of such helmets, or ophthalmic optical instruments to identify image quality. Therefore, the method can quickly perform a virtual evaluation of the image quality of multiple measurement positions and different apertures in the field of view, such as for AR / VR measurement technology and generally for measurement technology of ophthalmic optical systems, such as telescopes, glasses or corrective lenses. So-called near-eye displays can also be identified. Advantageously, the imaging quality can be determined for different positioning of the pupil in the field of view. The device can advantageously be designed to perform the determination in the range of 1 to 3 seconds by a one-time measurement (i.e., only by one measurement). This can advantageously reduce the complexity of the device to save costs.

[0020] According to one embodiment, the device may have a light source for illuminating the optical system under test when the optical system under test is received in the receiving device. The light source may be formed, for example, as a light emitting diode (LED) or, for example, as a laser light source. In this case, the light source is designed to emit light and thus illuminate the optical system under test.

[0021] An additional optical system for collimating the light beam emitted from the light source may be arranged behind the light source. The optical system for collimating the light beam emitted from the light source may advantageously be implemented as a projection unit, which may include, for example, at least one optical lens.

[0022] Furthermore, the other optical system can be pivoted at an angle to the optical axis of the optical system to be measured. This pivotability allows the other optical system to be advantageously pivoted to such an extent that one or more component image qualities can be measured at at least one off-axis field of view angle.

[0023] According to one embodiment, another optical system for capturing an optical wavefront profile may have a telescope and a Shack-Hartmann sensor. The telescope and the Shack-Hartmann sensor may advantageously be enclosed by a common housing and may be referred to as components of another optical system. These components may, for example, be arranged fixedly (i.e. stationary relative to each other) inside the housing so that an object at a fixed distance from the housing is imaged onto the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the present invention are illustrated in the accompanying drawings and will be described in detail in the following description. Figure 1 A schematic diagram of an embodiment of a device for measuring the imaging quality of an optical system under test; Figure 2 A schematic diagram of an embodiment of a device for measuring the imaging quality of an optical system under test; Figure 3 A schematic diagram of an embodiment of a portion of a measurement plane having a three-dimensional wavefront profile; Figure 4 A schematic diagram of an embodiment of a three-dimensional representation of a partial wavefront profile; Figure 5 A flow chart of an embodiment of a method for determining the imaging quality of an optical system under test; Figure 6 A flow chart of an embodiment of a method for determining the imaging quality of an optical system under test; Figure 7 is a schematic diagram of an operating device for an optical system under test according to an embodiment; and Figure 8 is an illustration of a measurement plane according to one embodiment.

[0025] In the following description of the preferred embodiments of the present invention, components illustrated in the various figures and having similar functions will be denoted by the same or similar reference numerals, and description of these components will not be repeated. DETAILED DESCRIPTION

[0026] Figure 1A schematic diagram of an embodiment of a device 100 for determining the imaging quality of an optical system 102 under test is shown. For example, the device 100 may also be referred to as a measuring device or a testing device. The optical system 102 is implemented, for example, as a spectacle lens, a waveguide, or another component, for example, used in combination with smart glasses or used as AR / VR glasses in the field of augmented reality (AR) or virtual reality (VR). To this end, the device 100 has a receiving device 104 for receiving the optical system 102 under test. The shape of the receiving device 104 is shown here only by way of example. The receiving device 104 may be implemented, for example, as a gripping arm or a holding arm, which further optionally holds the optical system 102 at at least one system edge. The device 100 further has another optical system 106, which is used to capture an optical wavefront profile 107 in a measurement plane behind the exit pupil of the optical system 102 under test. For example, the other optical system 106 can also be referred to as a sensor device, because according to the present embodiment, the other optical system has a sensor unit 108 implemented as a wavefront sensor or a Shack-Hartmann sensor. According to the present embodiment, the optical system 106 optionally includes a telescope 110. The device 100 further has an evaluation device 112 connected to the other optical system 106, and the evaluation device is designed to use the wavefront profile 107 to determine the optical sub-wavefront profile for each of the multiple sub-apertures of the measurement plane, and further use the determined optical sub-wavefront profile to determine the optical sub-image quality for each sub-aperture, and then use the sub-image quality to explain the spatial distribution of the imaging quality in the selected measurement plane. The evaluation device 112 can also be understood as a calculation unit, which is designed to control and / or execute a method for determining the imaging quality of the optical system 102 under test. Reference will be made below to Figures 5 and 6 The corresponding method is described in detail. According to one embodiment, the further optical system 106 also has a housing 114, which is designed to protect the telescope 110 and the sensor unit 108 from external influences. As an alternative, the further optical system 106 can be pivoted around the optical axis 116 of the optical system 102 under test in at least two opposite directions 118, for example.

[0027] The device 100 optionally has a light source 120, which is designed to illuminate the optical system 102 under test when the optical system 102 under test is received in the receiving device 104. To this end, according to the present embodiment, the light source 120 emits a light beam 122 having predetermined light parameters in the direction of the optical system 102 under test. The light beam 122 penetrates the optical system 102 under test, and the light beam emitted from the optical system 102 under test is captured by the sensor unit 108.

[0028] In other words, the invention relates to measuring the image quality of an optical system 102 worn close to the eye. In addition to eyeglasses, the optical system also includes, in particular, waveguides in augmented reality or virtual reality (AR / VR) devices. In such applications, electronically generated images are projected into the field of view of the viewer. In order to allow the user to perceive without restriction, it is important to have a sufficiently good image quality within the range of eye movement. This range is called the so-called "field of view". The field of view is understood here as a three-dimensional volume in which the center of rotation of the eye must be located in order to be able to perceive the entire image completely through eye movements. According to this embodiment, a further optical system 106 is arranged in the field of view area.

[0029] The image quality within the field of view is an important quality parameter, which can be advantageously checked by the method proposed by the invention. For example, the image quality expressed in terms of the modulation transfer function (MTF) and optionally various other parameters is measured at each eye position (more precisely, at each pupil position) within the field of view. Merely as an alternative, the invention enables a complete check of the entire volume enclosed by the field of view, which volume is understood within the scope of the invention as the measurement volume. The measurement volume typically has dimensions of 25 mm×25 mm×25 mm. Other characteristic parameters, such as the intensity distribution within the field of view, can also be optionally determined by means of the measurement data determined with the wavefront sensor 108.

[0030] According to one embodiment, the device 100 comprises a light source 120, which optionally has optics for beam shaping, depending on whether the optical system 102, also referred to as the sample, is illuminated in a collimated manner or in a divergent manner. For example, if an afocal optical system 102 is concerned, such as a waveguide for AR / VR glasses, collimated illumination of the optical system 102 is required. A further optical system 106 is located behind the optical system 102, which is fixed on a suitable support, i.e. the receiving device 104, and is used to measure the wavefront profile 107. In the example illustrated here, the further optical system optionally comprises a Shack-Hartmann sensor as the sensor unit 108, with a telescope 110. According to this embodiment, the telescope 110 is designed to adjust the beam cross section so that the capture surface of the sensor unit 108 is sufficiently illuminated. The capture surface of the Shack-Hartmann sensor typically has a size of 7 mm×7 mm to 15 mm×15 mm. The telescope 110 and the sensor unit 108 are exemplarily mounted in a common housing 114. According to the present embodiment, the measurement results are evaluated in an evaluation device 112 (e.g., a PC) referred to as a computing unit. In addition, the housing 114 and the further optical system 106 can be rotated by a defined angle so that the wavefront profile 107 can also be measured when the field of view angle is greater than 0°. As an alternative to a Shack-Hartmann sensor, the sensor unit 108 can also be implemented as a wavefront sensor based on other measurement principles.

[0031] Figure 2 FIG. 1 is a schematic diagram of an embodiment of a device 100 for measuring the imaging quality of an optical system 102 under test. Figure 1 According to the present embodiment, an additional optical system 200 for collimating the light beam emitted from the light source 120 is arranged behind the light source 120. The additional optical system 200, for example, has one or more lenses for guiding light. The light source 120 and the additional optical system 200 are, for example, implemented as a projection unit 202 as a whole.

[0032] According to the present embodiment, the light emitted from the projection unit 202 is projected onto the entrance pupil 204 of the measured optical system 102, which is located on the common axis 205. The optical system 102 further has an exit pupil 206, through which the collimated light beam 122 is finally emitted in the direction of the field of view 208, within which the wavefront profile of the light beam is captured on multiple measurement planes (e.g., the measurement plane 210 and at least one other measurement plane 211). According to the present embodiment, four measurement planes 210, 211 that are arranged at a fixed distance relative to each other and can each have a certain curvature are exemplarily illustrated. In addition, the recording of the wavefront profile 213 on the entire measurement plane 210 is also exemplarily shown. In addition, the recording of the partial wavefront profile 215 is also illustrated.

[0033] Figure 2 Also indicated is a portion 212 of the field of view 208, which will be described in more detail in a diagrammatic manner in at least one of the following figures. The portion 212 represents, for example, a certain eye position and sub-aperture.

[0034] Figure 3 A simplified diagram of an embodiment of a wavefront profile 213 in a measurement plane 210 is shown. The wavefront shown here corresponds, for example, to Figure 2 , and correspondingly shows the wavefront measurement result on the entire measurement plane 210. Taking a waveguide for AR as an example, the wavefront profile 213 of the measurement plane 210 includes a sub-aperture 212 of the measurement plane 210 in the field of view 208. The sub-aperture 212 has, for example, a partial wavefront profile 215 exemplarily presented in a simplified diagram in the figure below.

[0035] According to the present embodiment, the wavefront profile 213 in the measurement plane 210 is presented as a three-dimensional diagram in an xyz diagram, with the coordinate axes omitted for clarity.The field of view itself typically has dimensions of, for example, 25 mm x 25 mm x 25 mm.

[0036] Figure 4 A schematic diagram of an embodiment of a partial wavefront profile 215 is shown. The partial wavefront profile 215 corresponds to, for example, Figure 3 The partial wavefront profile 215 from the sub-aperture 212 mentioned in FIG. 2 is only shown in an enlarged manner. The partial wavefront profile 215 corresponds to a size commonly used to locate the pupil in the field of view, namely a diameter of 3 mm. Figures 5 and 6 At least one of the methods described in is used to determine the imaging quality of such an area. When the entire wavefront profile 213 in the measurement plane 210 is known, the partial wavefront profiles can be determined for any number of subapertures 212 so as to perform a virtual scan in the x and y directions. The virtual z-positioning is calculated, for example, by beam tracing. In this case, the measurement time is, for example, between 1 and 3 seconds and, for example, only a less complex measuring device is required.

[0037] Figure 5 A flow chart of an embodiment of a method 500 for determining the imaging quality of an optical system under test is shown. Figure 1 to Figure 2To this end, the method 500 includes a step 502 of capturing an optical wavefront profile in a measurement plane behind an exit pupil of the optical system, a step 504 of determining an optical sub-wavefront profile for each of a plurality of sub-apertures of the measurement plane using the wavefront profile, a step 506 of determining an optical sub-image quality for each sub-aperture using the determined optical sub-wavefront profile, and an optional step 508 of determining an image quality distribution in the measurement plane using the sub-image quality, which optional step is only exemplarily illustrated in FIG. Figure 3 to Figure 4 The method 500 further comprises a step 510 of dividing the measurement plane into a plurality of sub-apertures. According to this embodiment, the dividing step 510 is performed before the determining step 504. For example, the sizes of the plurality of sub-apertures are different from the sizes of the plurality of optional other sub-apertures of other measurement planes.

[0038] According to this embodiment, a wavefront sensor is used to capture the wavefront profile in the measurement plane in the capturing step 502. In the measuring step 504, a single sub-wavefront profile is further measured for each of the multiple sub-apertures by measuring the wavefront profile in the measurement plane, so that in the measuring step 506, the sub-image quality is measured for each sub-aperture using the measured sub-wavefront profile corresponding to each sub-aperture.

[0039] Optionally, the method 500 further comprises other steps, such as a determination step 509, which is performed before the capturing step 502, in which the measurement volume is determined. In this case, the measurement plane represents, for example, a cross section of the measurement volume.

[0040] According to one embodiment, the method 500 further comprises a step 512 of capturing other optical wavefront profiles in other measurement planes, for example using other wavefront sensors or using the wavefront sensor used to capture the first wavefront. In a determination step 514, other optical partial wavefront profiles are determined for each of a plurality of other subapertures of other measurement planes using the other wavefront profiles. Prior to this, the division step 510 is also applied to other measurement planes.

[0041] According to the present embodiment, the method 500 comprises a step 516 of determining other optical component image qualities for each of a plurality of other sub-apertures of other measurement planes behind the exit pupil of the optical system, so as to determine the distribution of the image qualities by calculation using the other component image qualities in the optional determination step 508. The measurement plane and the other measurement planes are linearly spaced apart along the optical axis of the optical system, thereby making the calculated component image quality distribution within a volume.

[0042] The method 500 further optionally includes a step 518 of calculating other wavefront profiles in other measurement planes using the wavefront profile of the measurement plane. The calculation step 518 should be understood as an implementation variant or as a supplement to the step 512 of capturing other optical wavefront profiles. According to this embodiment, the second wavefront profile in the second measurement plane is calculated, for example, by a ray tracing algorithm. If the calculation step 518 is performed, then in the determination step 514, the calculated other wavefront profile is used to determine other optical sub-wavefront profiles for each of the multiple other sub-apertures of the other measurement planes.

[0043] In a corresponding manner, more other wavefront profiles of more other measurement planes can be determined and used to determine the imaging quality.

[0044] Figure 6 A flow chart of an embodiment of a method 500 for determining the imaging quality of an optical system under test is shown. The method 500 corresponds to, for example, Figure 5 The method 500 described in the embodiment differs only in the representation of the flow chart. According to the present embodiment, the method 500 also includes a determination step 509 for determining the measurement volume before the capture step 502 and a step 510 for dividing the measurement plane into a plurality of sub-apertures before the determination step 504. According to the present embodiment, each step can be repeatedly performed. For example, after the step 508 of determining the image quality distribution using the previously determined sub-image quality, the capture step 502 is performed again for other measurement planes.

[0045] As an alternative, in step 518, the wavefront profile of the measurement plane is used to calculate other wavefront profiles in other measurement planes, and then the imaging quality in other measurement planes is determined using the previously captured data.

[0046] In other words, in a first method step 502, the optical wavefront profile in a first measurement plane located behind the exit pupil of the optical system to be measured is captured by a measurement technique. For example, a Shack-Hartmann wavefront sensor can be used here. Of course, other methods (such as interferometry) can also be used for optical wavefront measurement. For this purpose, the measurement plane includes, for example, the cross-sectional size of the entire exit pupil or field of view of the specimen or a part thereof. Optionally, the required measurement volume is defined in a preparatory step 509.

[0047] In the next step 510, the measurement plane is divided into a plurality of small sub-apertures or sub-areas. The size of each sub-aperture is of the order of magnitude of the pupil of the human eye (equivalent to the size of the pupil of the human eye), i.e., for example, a diameter of 2.5 mm. This setting can also be optionally adjusted in the preparation step. In other words, in the division step 510, the entire wavefront of the measurement plane is subdivided or divided into a plurality of partial wavefronts. Then, in the determination step 504, the wavefront profile of each single sub-aperture is determined from the wavefront profile of the entire measurement plane. In the determination step 506, local parameters of the local imaging quality of the sample inside the sub-aperture are determined from each partial wavefront. Such parameters are, for example, the modulation transfer function (MTF) or aberrations, such as coma or astigmatism.

[0048] Since the imaging quality of each sub-aperture in the measurement plane is now known, the distribution of the imaging quality parameter (e.g., MTF) over the entire measurement plane can be described in a further step 508. For example, eye positions where the MTF exceeds or falls below a predetermined threshold can be described. This allows a detailed evaluation of the MTF distribution in the measurement plane without having to explicitly measure the wavefront at each possible eye position, which can shorten the measurement time overall. For this purpose, a corresponding threshold comparison can be performed in step 508, for example.

[0049] In order to determine the imaging quality in the entire measurement volume, according to the present exemplary embodiment, the distribution of the optical wavefront about the optical axis of the sample is determined in a subsequent method step 518. More precisely, the wavefront profile in at least one further measurement plane at a defined distance z from the first measurement plane is determined by calculation. Figure 5 518. If the wavefront profile is measured at the first z-direction position, the wavefront profile calculation is performed, for example, by a ray tracing algorithm. According to this embodiment, the image quality at each pupil position is also determined based on the wavefront measured in a computational manner. This step 518 can be repeated for any number of planes in the entire measurement volume.

[0050] As an alternative, after completing step 508 (determining the image quality distribution in one measurement plane), the wavefront profile in the other measurement plane can be captured in a measuring manner by repeating the capture step 502 for the other measurement plane (for example, moving the wavefront sensor along the z-axis). Step 502 can also be repeated for any number of measurement planes. In principle, it can also be combined with steps 502 and 518.

[0051] Figure 7 A schematic diagram of an operating device 700 of an optical system 102 under test according to an embodiment is shown. The optical system 102 corresponds to, for example, Figure 1 or Figure 2According to the embodiment, the projection unit 202 is oriented toward the optical system 102, wherein the projection unit 202 is at least Figure 2 In addition, the operating device 700 shown here is similar to the projection unit 202 described in Figure 2 The device structure is consistent with that described in . However, this embodiment shows the eye 702 of the viewer. In the schematic diagram of the waveguide for AR, the pupil 704 of the viewer is schematically positioned in the area of ​​the three-dimensional field of view 208 .

[0052] Figure 8 A view of a measurement plane 210 according to an embodiment is shown. The measurement plane 210 is plotted in a diagram having an x-axis and a y-axis, each of which shows a spatial dimension of the measurement plane 210 in millimeters. The measurement plane 210 represents a cross section of the field of view. The measurement plane 210 is exemplarily presented as a square and is subdivided into a plurality of (e.g., 16) square segments 812. Each segment 812 corresponds to an eye position. Each segment 812 has a sub-aperture 212. Adjacent sub-apertures 212 may have overlapping areas. Each sub-aperture 212 and each eye position is exemplarily assigned an MTF value as a sub-image quality 820. The illustrated sub-aperture 212 has, for example, an MTF value between 0.2 and 0.9.

Claims

1. A method (500) for measuring the imaging quality of an optical system (102) under test, characterized in that: The method (500) comprises the following steps: capturing (502) an optical wavefront profile (107, 213) in a measurement plane (210) behind an exit pupil (206) of the optical system (102); dividing (510) the measurement plane (210) into a plurality of sub-apertures (212); Determining (504) an optical component wavefront profile (215) for each of a plurality of subapertures (212) of the measurement plane (210) using the wavefront profile (107, 213); and The optical component image quality (820) is determined (506) for each of the sub-apertures (212) using the determined optical component wavefront profile (215).

2. The method (500) according to claim 1, characterized in that: In the capturing step (502), a wavefront profile (107, 213) in the measurement plane (210) is captured using a wavefront sensor.

3. The method (500) according to any one of the preceding claims, characterized in that Comprising a step (509) of determining a measurement volume before the capturing step (502), the measurement plane (210) representing a cross section of the measurement volume.

4. The method (500) according to any one of the preceding claims, characterized in that The method comprises the steps of capturing other optical wavefront profiles in other measurement planes (211) (512), and determining other optical sub-wavefront profiles (215) for each of a plurality of other sub-apertures of the other measurement planes (211) using the other wavefront profiles (514).

5. The method (500) according to any one of claims 1 to 3, characterized in that: The method comprises the steps of calculating (518) at least one other wavefront profile in another measurement plane (211) using the wavefront profile (107, 213) of the measurement plane (210), and determining (514) other optical sub-wavefront profiles (215) for each of a plurality of other sub-apertures of the other measurement plane (211) using the other wavefront profile.

6. The method (500) according to claim 4 or 5, characterized in that: The method comprises the step (516) of determining other optical component image qualities (820) for each of a plurality of other subapertures of the other measurement plane (211) behind the exit pupil (206) of the optical system (102).

7. The method (500) of claim 5, characterized in that: In the calculation step (518), other wavefront profiles in the other measurement plane (211) are calculated by a ray tracing algorithm.

8. The method (500) according to any one of claims 4 to 7, characterized in that: The size of the plurality of sub-apertures (212) is different from the size of the plurality of other sub-apertures.

9. A device (100) for measuring the imaging quality of an optical system (102) under test, characterized in that: The device has the following features: A receiving device (104) for receiving the optical system (102) under test; Another optical system (106) for capturing an optical wavefront profile (107, 213) in a measurement plane (210) behind an exit pupil (206) of the optical system (102) under test; as well as An evaluation device (112) is used to divide (510) the measurement plane (210) into a plurality of sub-apertures (212), use the wavefront profile (107, 213) to measure an optical sub-wavefront profile (215) for each of the plurality of sub-apertures (212) of the measurement plane (210), and use the measured optical sub-wavefront profile (215) to measure the optical sub-imaging quality (820) for each of the sub-apertures (212).

10. The device according to claim 9, characterized in that A light source (120) is included, which is used to illuminate the optical system (102) under test when the optical system (102) under test is received in the receiving device (104).

11. The device (100) according to claim 10, characterized in that An additional optical system (200) for collimating a light beam (122) emitted from the light source (120) is arranged behind the light source (120).

12. The device (100) according to any one of claims 9 to 11, characterized in that The other optical system (106) can be pivoted at a certain angle to the optical axis (116) of the optical system (102) under test.

13. The device (100) according to any one of claims 9 to 12, characterized in that The other optical system (106) for capturing the optical wavefront profile (107, 213) has a telescope (110) and a Shack-Hartmann sensor.

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