Device and method for determining imaging quality of at least one image of sample

Abstract

The invention relates to a device (100) for determining the imaging quality of at least one image of a sample (105), comprising: at least one projection unit (115) for outputting light (120) in the direction of the sample (105) in order to project at least one luminescent and / or illuminated object structure and to penetrate the sample (105); an optical receiving unit (110) for receiving light beams (130) of light (120) representing at least one image of the structure of the projected object; a holder unit (145) disposed between the projection unit (115) and the optical receiving unit (110); and a calculation unit (150) for simultaneously evaluating a first light parameter representing at least one optical light parameter and a second light parameter representing at least one chromaticity or photometric light parameter of the light beam (130) transmitted through or reflected at the sample (105) in order to determine the imaging quality of the at least one image. The computing unit (150) is connected to the projection unit (115), the receiving unit (110) and / or the holder unit (145).

Description

Technical Field

[0001] The present invention relates to a device and a method for determining the imaging quality of at least one image of a specimen, of the type described in the independent claims. The invention also relates to a computer program. Background Art

[0002] US 11029 206 B2 describes a device for measuring and characterizing the performance of augmented reality and virtual reality waveguide structures using a glass substrate. Summary of the Invention

[0003] In this context, the present invention provides an improved device and an improved method as described in the respective independent claims for determining the imaging quality of at least one image of a specimen. In addition, a computing unit using this method is provided, and finally, a corresponding computer program is provided. By means of the measures listed in the dependent claims, the device provided in the independent claims can be advantageously further designed and improved.

[0004] The present invention can reliably determine the characteristics of a specimen. For example, the device can be used as a measuring device for this purpose. Advantageously, the quality of the specimen can be improved thereby, and thus the quality of, for example, a near-eye display (NED), such as a near-eye display that can be used in combination with smart glasses, augmented reality (AR) or virtual reality (VR), can be improved. For example, the image can be clearly displayed, which has a positive impact on the health of the end user. Advantageously, an imaging colorimeter, an imaging photometer, and an optical parameter measurement system can all be used to simultaneously achieve color measurement and improvement of the optical parameter measurement system.

[0005] The present invention provides a device for determining the imaging quality of at least one image of a specimen, wherein the device has at least one projection unit for outputting light in the direction of the specimen in order to project at least one luminous and additionally or alternatively illuminating object structure onto the specimen. In addition, the device has an optical receiving unit for receiving the light transmitted through the specimen or reflected at the specimen, the light beams representing at least one image of the projected object structure. The receiving unit has an optical device and an optical detector. In addition, the device has a support unit for holding the specimen to be tested and a computing unit, wherein the support unit is arranged between the projection unit and the optical receiving unit, and the computing unit is used to simultaneously evaluate a first optical parameter and a second optical parameter of the light transmitted through the specimen or reflected at the specimen and received by the receiving unit, the first optical parameter representing at least one optical parameter, and the second optical parameter representing at least one chromaticity or photometric parameter, in order to determine the imaging quality of at least one image of the specimen. The computing unit is connected to the projection unit and the receiving unit, and additionally or alternatively connected to the support unit.

[0006] The device can be, for example, a measuring device for an augmented reality system (AR) or a virtual reality system (VR) (also simply referred to as AR / VR), through which the characteristics of a specimen can be measured. The specimen can be designed, for example, as smart glasses or a lens of an AR / VR device, which is also called a near-eye display (NED), and an image can be displayed thereon, for example. In addition, the specimen can also be designed, for example, as a complete system, and the imaging quality can be determined for this complete system. For this purpose, it is advantageous to determine the imaging characteristics in advance. That is to say, the specimen can be designed as an optical system, waveguide, waveguide combination or module to be measured, with a lighting unit and a waveguide. The module can generate a self-luminous object structure, which can be detected by the receiving unit. The object structure can advantageously represent a pattern, image or symbol to be imaged on the specimen.

[0007] The projection unit can advantageously have a light source, such as a light-emitting diode (LED). In addition, the projection unit can be aligned with the specimen so that light can be transmitted through the specimen or reflected at the specimen. Advantageously, the light can be directly transmitted through the specimen, or enter the specimen at the incident point and, for example, be reflected on the opposite surface of the specimen until it reaches the exit point of the specimen. The exit point can advantageously be in line with the receiving unit so that the transmitted or reflected light beam can be received by the receiving unit. The receiving unit can advantageously have an optical device and a detector. The optical device can have, for example, a lens or other optical elements. The detector can also advantageously have a plurality of components through which the light beam can be detected and, additionally or alternatively, the information transmitted by these light beams can be detected. The computing unit can advantageously be designed as a control unit or a control device for processing such information. Among them, this information can be transmitted and utilized by means of light parameters, and then the imaging quality of the image can be inferred or calculated. In order to obtain meaningful results, the device can have a support unit on which the specimen can be mounted. The support unit can advantageously be designed to be movable or moveable so that the imaging quality can be determined by the computing unit according to different positions of the specimen. The support unit can advantageously be designed as a multi-axis linear platform, which allows the specimen to be freely positioned in space and can thus be moved one or more times, for example, along the x-axis, y-axis or z-axis.

[0008] According to one embodiment, the detector of the receiving unit may have a plurality of spectral channels and at least one image sensor. Among them, the spectral channels can be realized, for example, by a filter unit. The filter unit can advantageously be designed as a filter wheel with a plurality of filters. Such filters can be designed, for example, as glass or plastic sheets with optical quality, and the glass or plastic sheets can enter the optical path of the receiving unit (for example, in a pivoting manner) so as to obtain a clear wavelength spectrum in the image. As an alternative, the spectral channels can be realized by a plurality of image sensors each having a spectral filter. In both variants, the spectral filter can be further combined with a neutral density filter in order to uniformly weaken the incident light intensity on the image sensor, thereby avoiding possible overmodulation of the sensor. Accordingly, the detector can be realized, for example, as a sensor unit. In addition, the detector of the receiving unit can also be realized as a focusable camera.

[0009] In addition, the receiving unit may also have an optical device that is diffraction-limited over the entire detectable field of view. The optical device can advantageously have at least one lens, especially a plurality of lenses, and the lens or lenses can be designed to be able to direct the light beam to the detector. Among them, the resolution of the optical instrument (in this case, referring to the optical device) is limited by diffraction and the field of view. For this purpose, the field of view can be, for example, a characteristic parameter regarding the field of view of the receiving unit, that is, a characteristic parameter related to the detection range.

[0010] The optical device can have replaceable components and at least one adjustable optical aperture stop, and the optical aperture stop can be designed to be able to adjust the geometric characteristics, especially the diameter, of the light beam entering the optical device. For example, the design of the optical device can be similar to a conoscopic lens. The adjustable aperture stop can be used, for example, to simulate the iris diameter of the human eye. The optical aperture stop can be advantageously adjusted physically or virtually and can be further designed, for example, as an opening capable of receiving the light beam. By adjusting the optical aperture stop, the amount of received light can be advantageously determined so as to obtain the correct illumination conditions.

[0011] According to one embodiment, the projection unit can be designed as a focusable or non-focusable collimator, and the collimator especially can have at least one reticle element with monochromatic illumination and additionally or alternatively with polychromatic illumination. The receiving unit correspondingly has an imaging telescope in order to image the image generated by the collimator from infinity onto the sensor. Among them, the collimator can be designed to be able to generate light with an approximately parallel optical path from a divergent light source. Thereby, the light can be advantageously directed to a specific direction. "Monochromatic" can refer to, for example, light emission with a very narrow wavelength range. Therefore, "polychromatic" can refer to polychromatic light composed of different colors, and thus can be spectral broadband light and can have different wavelengths. The reticle element can also be advantageously referred to as a reticle or graticule.

[0012] In addition, the projection unit may have at least one reticle element that includes a plurality of different object structures. As an alternative, the projection unit may have a replacement mechanism for successively feeding different reticle elements having different object structures into the optical path of the light. In particular, the object structures may represent large-area elements, sharp edges, and may additionally or alternatively represent lines. A reticle element having a plurality of different object structures may be referred to as a multi-feature reticle, for example. Accordingly, the object structure may be, for example, a pattern having a curved or straight profile or line. Accordingly, the object structure may be implemented as, for example, a circle, a quadrilateral, or a cross, etc., and may be displayed on or by the specimen, for example.

[0013] According to one embodiment, the object structure may be generated by or may be generated from self-luminous elements. As a supplementary or alternative solution, the projection unit may have an adjustable projection aperture stop. The object structure may advantageously be implemented as a virtual structure. To be able to image it, the projection unit may be equipped with a projection aperture stop that is designed, similar to an optical aperture stop, as an opening for outputting light. The projection aperture stop may advantageously be implemented physically or virtually and may additionally or alternatively be adjustable to limit the diameter of the light beam emitted from the projection unit. In addition, the projection unit may optionally be equipped with an additional projection field stop, which may itself optionally be adjustable to adjust the field angle of the outgoing light beam.

[0014] The device may also have a movable first goniometer and a movable second goniometer. The first goniometer may be connected to the projection unit, and the second goniometer may be connected to the receiving unit, where the first and second goniometers may be designed to be able to move the projection unit and the receiving unit independently of each other around a defined pivot point in at least two different directions. In particular, the first goniometer and / or the second goniometer may be translated relative to the specimen in at least three spatial directions. The goniometer or goniometers may also be referred to as angle gauges, for example, and may measure the angle between the projection unit and the receiving unit, for example. This means that the goniometers may be connected to each other and may be connected to the projection unit or the receiving unit, respectively, at their free ends. Thereby, the projection unit and the receiving unit may advantageously be moved in different directions to be able to measure and determine the imaging quality of the specimen from different positions, and thus measure and determine the illumination of the light. Advantageously, the goniometers may be pivoted.

[0015] In addition, a method for determining the imaging quality of at least one image of a specimen using the device in one of the aforementioned variants is proposed, wherein the method includes the step of using a projection unit to output light so as to be able to project at least one luminous and additionally or alternatively illuminated object structure onto the specimen. Further, the method includes the step of using a receiving unit to receive the light beams transmitted through the specimen or reflected at the specimen, which light beams represent at least one image, and the step of simultaneously evaluating a first light parameter (representing at least one optical light parameter) and a second light parameter (representing at least one chromaticity or photometric light parameter) of the light beams transmitted through the specimen or reflected at the specimen, so as to use a calculation unit to determine the imaging quality of at least one image.

[0016] The imaging quality of a specimen, which can be used in combination with, for example, smart glasses or an AR / VR system, can be determined in an advantageous manner by this method. Determining the imaging quality is beneficial for obtaining or inspecting image sharpness. In the output step, the output of light can, for example, last for a period of time, and this period of time can advantageously be adjustable.

[0017] According to one embodiment, in the receiving step, other light beams transmitted through the specimen or reflected at the specimen can be received, and these other light beams can represent at least one other image. In the evaluation step, other first light parameters (which can represent at least one other optical light parameter) and other second light parameters (which can represent at least one other chromaticity or photometric light parameter) of the other light beams can be simultaneously evaluated so as to be able to determine the other imaging quality of the other images. In particular, the images and the other images can be acquired with different exposure times respectively. For example, the exposure time of the light output for imaging can be the same or different.

[0018] The method can further include the step of combining the image and the other images into an overall image after the evaluation step. Advantageously, in the case where the imaging exposure times are different, an overall image in the form of a high dynamic range (HDR) image (i.e., an image with a large brightness difference) can be generated. As an alternative, in the case of using different spectral settings for the light beams, an overall color image can be generated using the light parameters during imaging. It is possible to select to determine the light parameters for a single image or an overall image.

[0019] According to one embodiment, the method can further include the step of compensating for imaging errors using predetermined calibration data before the evaluation step. Before evaluating the light parameters to determine the imaging quality, the compensation step can advantageously correct the imaging errors to improve the imaging quality. The calibration data can advantageously be stored in a storage unit.

[0020] This method can be implemented, for example, in a control device in the form of software or hardware or a combination of software and hardware.

[0021] The present invention further provides a computing unit, which is designed to implement, control, or realize the steps of the variants of the methods proposed herein in a corresponding device. Through this implementation of the present invention in the form of a computing unit of a control device, the object of the present invention can also be achieved quickly and effectively.

[0022] To this end, the computing unit for processing signals or data may have at least one storage unit for storing signals or data, at least one interface leading to a sensor or an actuator to read in sensor signals from the sensor or output data signals or control signals to the actuator, and / or at least one communication interface for reading in or outputting data embedded in a communication protocol. The computing unit may be, for example, a signal processor, a microcontroller, or a similar element, where the storage unit may be a flash memory or a magnetic storage unit. The communication interface may be designed to read in or output data in a wireless and / or wired manner, where the communication interface capable of reading in or outputting wired data may, for example, read in such data from a corresponding data transmission line in an electrical or optical manner, or output it to the corresponding data transmission line.

[0023] Herein, a "computing unit" may be understood as an electrical device that processes sensor signals and outputs control signals and / or data signals accordingly. The computing unit may have interfaces, which may be designed in terms of hardware and / or software. In a hardware-based design, these interfaces may be, for example, part of a so-called system ASIC that incorporates various functions of the device. However, these interfaces may also be independent integrated circuits, or at least partially composed of discrete components. In a software-based design, these interfaces may be, for example, software modules that exist on a microcontroller together with other software modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the present invention are illustrated in the accompanying drawings and will be elaborated in detail in the following description.

[0025] Figure 1 Schematic diagram of a device according to an embodiment.

[0026] Figure 2 Schematic diagram of an embodiment of the device.

[0027] Figure 3 Schematic diagram of an embodiment of the physical structure for the device.

[0028] Figure 4 Schematic diagram of an embodiment of the physical structure for the device.

[0029] Figure 5 Schematic diagram of an embodiment of the physical structure for the device.

[0030] Figure 6 Schematic diagram of an embodiment of the physical structure for the device.

[0031] Figure 7 Flowchart of an embodiment of a method for determining the imaging quality of an image of a specimen.

[0032] Figure 8 Block diagram of a computing unit according to an embodiment, the computing unit being for a device. Detailed implementation

[0033] In the following description of advantageous embodiments of the present invention, elements having similar functions illustrated in the various figures will be denoted by the same or similar reference signs, and these elements will not be described repeatedly.

[0034] When an embodiment includes an "and / or" relationship between a first feature and a second feature, it should be understood that the embodiment has the first feature and the second feature according to one implementation, and has either only the first feature or only the second feature according to another implementation.

[0035] Figure 1 Schematic diagram showing a device 100 according to an embodiment. The device 100 is implemented, for example, as a measuring device for determining the imaging quality of at least one image of a specimen 105. Accordingly, different optical systems can be arranged in or on the device 100 to measure or determine its imaging quality. The specimen 105 is designed, for example, as a waveguide, a waveguide assembly or a module composed of an illumination unit and a waveguide assembly. In this case, the module can, for example, generate a self-luminous object structure that can be detected by the receiving unit 110 of the device 100.

[0036] Accordingly, the device 100 has at least one projection unit 115 for outputting light 120 in the direction of the specimen 105, so as to project at least one luminous and / or illuminating object structure onto the specimen 105. The projection unit 115 only optionally has an illumination unit for generating the light 120, namely a light source 125. The above-mentioned optical receiving unit 110 is also part of the device 100. The receiving unit 110 is used to receive the light beam 130 that has passed through or been reflected by the specimen 105. The light beam 130 represents at least one image of the projected object structure. In addition, the receiving unit 110 has an optical device 135 and a detector 140. The detector 140 has a plurality of spectral channels 141, an image sensor 142, and at least one filter unit 143, such as a filter wheel with color filters (such as V(λ) filters) and optionally additional neutral density filters (ND). The optical device 135 is diffraction-limited, for example, over the entire detectable field of view angle. In addition, the optical device 135 has replaceable components and at least one optically adjustable aperture stop 144, which can be adjusted physically or virtually, and is used to adjust the beam diameter entering the optical device. In addition, the optical device can be designed to correspond to, for example, a conoscopic lens.

[0037] According to this embodiment, both the projection unit 115 and the receiving unit 110 are arranged to be movable, especially pivotable. In addition, according to this embodiment, they are arranged on a common line, which, for example, corresponds to the optical path of the light 120 and the light beam 130. The specimen 105 is arranged between the projection unit 115 and the receiving unit 110. More precisely, the device 100 has a support unit 145 for holding the specimen 105. According to this embodiment, the support unit 145 is also designed to be movable so as to move the specimen 105 in the x, y, and z directions of the coordinate system. According to this embodiment, the device 100, for example, has a movable first goniometer 146 (also called a protractor) and a movable second goniometer 147. The first goniometer is connected to the projection unit 115, and the second goniometer is connected to the receiving unit 110. The first goniometer 146 and the second goniometer 147 are used, for example, to move the projection unit 115 and the receiving unit 110 independently of each other around a definite rotation point in at least two different directions. In particular, the first goniometer 146 and / or the second goniometer 147 can perform translational motion or migration relative to the specimen 105 in at least three spatial directions.

[0038] The device 100 further has a computing unit 150, which is used to simultaneously evaluate a first optical parameter (representing at least one optical light parameter) and a second optical parameter (representing at least one chromaticity or photometric light parameter) of the light beams 130 of the light 120 that are transmitted through the specimen 105 or reflected at the specimen 105 and received by the receiving unit 110, in order to determine the imaging quality of at least one image of the specimen 105. The computing unit 150 is connected to the projection unit 115, the receiving unit 110, and / or the support unit 145. According to this embodiment, the specimen 105 (which is formed by or includes an AR module here) further has a waveguide containing other projection units 155, and these other projection units are also connected to the computing unit 150. The projection unit 115 and the other projection units 155 are arranged offset or can be arranged offset. For example, the projection unit 115 is arranged such that the light 120 penetrates the specimen 105 in a straight line. According to this embodiment, the other projection units 155 are arranged such that other light 160 enters the specimen 105 at the incident point 165 (also known as the entrance pupil of the specimen 105) and is reflected on the surface of the specimen 105 until it hits the exit point 170 (also known as the exit pupil of the specimen 105). According to this embodiment, the light beams 130 and / or other reflected light beams 171 of the other light 160 exit at the exit point 170 and are then received by the receiving unit 110. The other projection units 155 also have other light sources 175 for outputting the other light 160.

[0039] In other words, according to this embodiment, a system and method for simultaneously measuring the total modulation transfer function (MTF), color MTF, and chromaticity or photometric parameters are introduced (see Figure 7 ). Thus, the device 100 is implemented as an integrated system, enabling users (such as users of near-eye display systems (NEDs), such as users in the AR / VR field) to use one measuring device to measure all the basic optical parameters of these systems, namely, optical and chromaticity quality.

[0040] Accordingly, the solution described in this specification relates to a method and apparatus 100 for simultaneously measuring the optical parameters (such as MTF) and chromaticity or photometric parameters of the components and modules of an NED system. For this purpose, by way of example only, the apparatus 100 has a sensor described herein in connection with the receiving unit 110, and at least one filter wheel is provided in front of the sensor. The filter wheel includes filters that can filter the incident light beam 130 in terms of total amount and spectrum individually or in combination, for example, weighting the color vision of the human eye. In addition, the receiving unit 110 further includes an optical system described as the optical device 135, which is mounted in front of the filter wheel and has a physical aperture 144 as the first element on the specimen side. The diameter of the physical aperture can be changed manually or automatically by performing a replacement operation or some adjustment. A basic characteristic of the optical device 135 is that it is designed to be diffraction-limited over the entire detectable field of view angle. In this case, the optical device 135 can have either a small field of view angle or a field of view angle corresponding to a conoscopic lens.

[0041] When measuring chromaticity or photometric parameters and optical parameters (such as MTF), a target is required for measurement. This target is characterized in that such an object structure includes both large-area homogeneous elements and sharp edges or lines. In addition to the target having these two characteristics, different targets each having one of the characteristics can also be used. In this case, the target can be optionally generated and projected by a self-luminous display element that is part of the specimen 105, or by a target projector that projects the target in such a way that the target penetrates the specimen 105. For example, for targets having only one characteristic, these targets are projected sequentially during operation. For example, an optional other projection unit 155 has other light sources 175 that can generate either different single wavelengths or polychromatic light with different spectral widths. In this embodiment, the projection unit 155 is part of the specimen 105 and can be implemented, for example, as an LCD or LCOS element. The projection unit 115 has a projection aperture stop 180, also known as the exit aperture, which is located outside on the side facing the specimen 105. In addition, the projection unit 115 has a uniformly illuminated target template 182. The projection unit 115 can adopt a design that is technically similar to that of the other projection unit 155. The light 120, 160 is guided to the entrance pupil of the specimen 105. The projection aperture stop 180 can be implemented physically or virtually.

[0042] In order to measure optical parameters and chromaticity or photometric parameters, the above-mentioned target is projected through a target projector or through the specimen 105 itself and made to penetrate the specimen 105, but this is only for illustration. The acquisition is carried out by the above-mentioned system in the manner of sequential image acquisition, and different degrees of filtering are carried out respectively with a filter wheel. The image acquisition at each filter position may include one image or multiple images under different exposure time conditions. In order to measure optical parameters and chromaticity parameters, the recorded data is transmitted to the calculation unit 150 for processing. For example, the processing includes but is not limited to combining images with different exposure times into a so-called high dynamic range image, combining images with different color weightings into a color image, and / or correcting distortions in single images and overall images. The processing may also optionally include correcting the acquired data using a calibration data set, and calculating optical parameters and chromaticity parameters. Among them, only for illustration, chromaticity parameters are obtained through a large-area structure, while optical parameters (such as MTF) are obtained in parallel by means of edges and lines.

[0043] In addition, the device 100 has at least one goniometer 146, 147. More precisely, the projection unit 115 and the receiving unit 110 can be respectively arranged on a goniometer 146, 147, which can enable the two components to perform independent biaxial rotation around their respective rotation points. The rotation points of each system are located, for example, at the respective apertures (such as the apertures of the specimen or the projection unit or the receiving unit), and any other position can also be achieved. According to this embodiment, both goniometers 146, 147 can be shifted manually or automatically at least once or multiple times in at least the X direction and the Y direction (optionally further in the Z direction). The task of the goniometers 146, 147 is to independently position the receiving unit 110 and the projection unit 115 relative to the specimen 105, so as to adjust at least one optical aperture stop 144 of the receiving unit 110 to a definite measurement position and form a definite angle with the specimen 105. When necessary, the exit pupil of the target projector can also be adjusted relative to the entrance pupil according to the definition of position and angle. In addition, the specimen 105 can be shifted at least in the X direction and the Y direction in a plane by means of the support unit 145. Accordingly, depending on the receiving unit 110, the measurement of the specimen 105 can be achieved by adjusting the positioning system or by sequentially positioning, recording and measuring at different positions and angles. For example, the positions of the system and the possible positions of the target projector required can be located on opposite sides of the specimen 105, or on the same side of the specimen 105. The specimen 105 is designed as a single waveguide or light guiding element, or a module composed of multiple identical or different components, or a complete system.

[0044] This means that the introduced device 100 and related methods are capable of simultaneously measuring optical imaging parameters as well as chromaticity and photometric parameters for the optical components or modules of a near-eye display (NED). In this context, the term NED refers to a device worn by a user, such as in the form of glasses, which is capable of projecting virtual images into the user's field of view, for example by means of augmented reality, mixed reality or extended reality technologies, or which is capable of generating a virtual environment, i.e. virtual reality.

[0045] Optical imaging parameters or optical parameters can be understood as variables characterizing the imaging quality of an optical system, such as the modulation transfer function (MTF) or the degree of distortion and the principal beam angle. Chromaticity and photometric parameters can be understood as variables characterizing the color perception of an optical system, such as the transmitted color components or the color representation in a color space. Photometric parameters can be understood as variables capable of describing the radiation characteristics or the amount of transmitted or reflected light of a specimen, such as the transmitted luminous flux or the luminous intensity. For the specific definitions of the above parameters and other parameters, please refer to the IEC 63145 and ISO 9241 series of standards.

[0046] The above solution can measure the above parameters simultaneously and is applicable to both individual components of the NED and pre-assembled modules or complete systems.

[0047] In other words, Figure 1 A first embodiment of the device 100 is illustrated in detail and described below, and its mode of operation is schematically explained. According to this embodiment, the device 100 to be tested or measured (device under test - DUT) is shown as an NED component. This component consists of an internal projection unit 155, which includes an illuminated LCD element and, for example, a waveguide, which is used to provide the image generated by the internal projection unit 155 to the viewer in a suitable manner. The device 100 is fixed in a mechanical support (such as a multi-axis linear stage), which allows the specimen 105 to be freely positioned in space. More precisely, the specimen 105 can be moved one or more times along the x-axis, y-axis and z-axis of the coordinate system by means of the stage. According to Figure 2 the illustrated embodiment and the corresponding description, the projection unit 115 is implemented as a collimator. The collimator has, for example, a fixed or variable focusing function. The projection unit 115 generally includes a light source 125, a reticle element 182, also known as a reticle or graticule, on which a structured object pattern is provided, and an optical system 184, such as a lens, which has a real or virtual exit aperture 180. The reticle element 182 is preferably connected to a diffuser disk to ensure uniform illumination of the object pattern. When the projection unit 115 is designed as a focusable collimator, the reticle element 182 can be moved relative to the optical system of the collimator, for example by means of a linear encoder, to simulate different object distances.

[0048] According to this embodiment, the structured object pattern advantageously includes both large-area homogeneous elements and sharp edges or lines. Both types of structures can be located on the reticle element 182, whereby the reticle element is implemented as or can be implemented as a so-called multi-feature reticle. As an alternative, a mechanical replacement mechanism can be provided, through which different reticle elements 182 with different structures are fed into the optical path of the projection unit 115. As an alternative, line structures can be used for two partial measurements. In this case, correction factors are used in the chromaticity and photometric evaluations to take into account the finite area fraction of the luminous structure. For example, when using a double cross or a ring, it is also possible to obtain the optical magnification in a measurement and consider it separately in the calculation. Figures 3 to 6 An example of a projectable object structure is shown.

[0049] The light source 125 of the projection unit 115 is, for example, multi-color, and appropriate means can be provided to limit or adjust the spectral bandwidth. The light source 125 is, for example, implemented as a single multi-color LED with a corresponding spectral filtering function, or as a combination of multiple monochromatic light beam sources. As an alternative, the projection unit can also be designed to generate a virtual object structure by itself using self-luminous elements (such as a display).

[0050] The device 100 also has an optical receiving unit 110, which is located on the opposite side of the projection unit 115. In the case of a reflection measurement of the specimen 105, the projection unit 115 and the receiving unit 110 can be arranged on the same side. Figure 1 An example of a transmission measurement is shown. However, the present invention is equally applicable to reflection measurements.

[0051] The receiving unit 110 itself consists of an optical system described as the optical device 135 and an image sensor, and the image sensor can be implemented as a multi-spectral detector 140, that is, a detector with multiple spectral channels. Other embodiments are a monochromatic detector with a filter unit or independent channels for spectral evaluation. In other words, the spectral sensitivity of the image sensor can be changed. Therefore, the image sensor can perform spectral weighting and / or filtering on the incident light beam. For example, hereby the spectral sensitivity of the sensor can be adapted to the spectral sensitivity of the human eye. In one embodiment, such a detector 140 can be achieved by a combination of at least one filter wheel with a V(λ) filter and an additional ND filter. According to this embodiment, the optical device 135 is arranged in front of the detector 140 and is designed to generate a diffraction-limited image within its entire detectable field of view (FOV). In addition, the optical device 135 has a plurality of replaceable components, so that the field of view angle of the optical device 135 can be adjusted according to different measurement specifications. When the maximum field of view angle is set, the design of the optical system corresponds, for example, to the design of a conoscopic lens, where as Figure 1 or Figure 2As shown, the first optical element is always the adjustable optical aperture stop 144. The optical aperture stop is preferably implemented as a physical stop, but can also be implemented as a virtual stop.

[0052] In addition, according to Figure 1 and Figure 2 the illustrated embodiment, the projection unit 115 and the receiving unit 110 are each fixed to a goniometer 146, 147 respectively, which can pivot or laterally shift independently of each other one or more times. The axes about which the projection unit and the receiving unit pivot are, for example, generally parallel to the relevant optical axis and / or intersect the center of the relevant entrance pupil or exit pupil. To achieve a lateral offset, each goniometer 146, 147 can also be mechanically connected to a multi-axis linear stage. The pivoting and / or shifting of the projection unit 115 is necessary in order to illuminate the specimen 105 at different positions and / or at different object angles, or to provide an object pattern at different positions or at different object angles. Application examples are as follows Figure 2 shown.

[0053] In other words and / or in summary, according to this embodiment, a device 100 for measuring the imaging quality of an optical system or module of an NED system is introduced, wherein the device 100 has a projection unit 115, a support unit 145 (also referred to as the mechanical support of the optical system or module or specimen 105 to be measured, which can be translated in three spatial directions), an optical receiving unit 110 and a calculation unit 150. The device 100 is capable of simultaneously determining the optical measurement parameters and the photometric or chromatic measurement parameters of the optical system or module 105 to be measured, wherein the optical receiving unit 110 consists of the optical imaging system previously described as the optical device 135 and an optical detector 140 having a plurality of spectral channels 141. The optical detector 140 can be implemented, for example, by a combination of an image sensor 142 and at least one filter element 143 (such as a pre-filter wheel with a V(λ) filter) and an optional other ND filter. According to this embodiment, the optical receiving unit 110 has an optical system 135 that is diffraction-limited over the entire detectable field of view angle. The optical system (i.e., the optical device 135 of the receiving unit 100) also optionally has replaceable components and at least one physical or virtual adjustable optical aperture stop 144, so as to limit the diameter of the incident light beam, for example, to simulate the dilation of the human iris. The optical system 135 can also be designed to correspond to a conoscopic lens.

[0054] According to this embodiment, the projection unit 115 can be alternatively implemented as a focusable or non-focusable collimator with a monochromatic illumination type and / or multi-color illumination type reticle element 182 (reticle), and also has a physical or virtual aperture stop that has been previously described as the exit aperture 180. The aperture stop can be selectively adjusted to limit the diameter of the light beam hitting the specimen. In addition, the projection unit 115 can include an adjustable field stop 181 that can also be implemented physically or virtually. This field stop is used to adjust the field angle of the outgoing light beam. Such adjustment may be necessary for some specimens in order to precisely adjust the input coupling angle of the waveguide under test. The reticle element 182 can also optionally include different object structures (multi-feature reticles), or be designed to enable reticles with different object structures to sequentially enter the optical path of the projection unit 115 through a replacement mechanism. For example, the object structure can be implemented as both large-area elements and sharp edges or lines, which are virtual structures generated by self-luminous elements. In other words, this means that the projection unit 115 has at least one reticle element 182 that includes multiple different object structures, or has a replacement mechanism for sequentially feeding different reticle elements (such as reticles) with different object structures into the optical path of the light 120. Specifically, these object structures represent large-area elements, sharp edges, and / or lines such as curved or straight lines. The object structure is a virtual structure generated by or can be generated by self-luminous elements. As a supplementary or alternative solution, the projection unit 115 has a physical or virtual projection aperture stop 180 and an optional physical or virtual projection field stop 181.

[0055] According to this embodiment, the projection unit 115 is used to illuminate the specimen 105 in a reflective or transmissive manner. For this purpose, the projection unit 115 is arranged, for example, on the first goniometer 146, and the receiving unit 110 is arranged on the second goniometer. In this way, the two units 110, 115 can each pivot around a definite rotation point in at least two directions. Accordingly, each goniometer 146, 147 can be translated in three spatial directions relative to the specimen 105 to be tested. The function of the device does not absolutely require goniometers. In this case, the receiving unit will be implemented as a conoscopic lens, and the projection unit will have an adjustable aperture stop or field stop in order to adapt the diameter of the light beam and the field angle to the specimen. In summary, the specimen is designed, for example, as a waveguide, a waveguide combination, or a module composed of an illumination unit and a waveguide combination, where the module can generate a self-luminous object structure that can be detected by the receiving unit 110 of the device 100.

[0056] Figure 2 Schematic diagram showing an embodiment of the device 100. The device 100 shown here is the same as Figure 1is similar to the device 100 described therein. According to this embodiment, in addition to the receiving unit 110, the computing unit 150, and the support unit 145 for holding the specimen 105, the device 100 shown here also has a projection unit 115. The specimen shown here does not have an independent active illumination or projection element 155. According to this embodiment, light 120 enters the specimen 105 through the incident point 165 and is reflected on the surface of the specimen 105 until it reaches the exit point 170, and the light beam 130 is output to the receiving unit 110. Additionally, according to this embodiment, the projection unit 115 is implemented as a focusable or non-focusable collimator, which particularly has at least one monochromatic illumination type and / or polychromatic illumination type reticle element 182 (reticle). It is conceivable that the (image) sensor 142 can also be focused accordingly. The collimator is used to generate light with an approximately parallel optical path from a divergent light source. Such collimation is generally used to give the light a specific direction.

[0057] In other words, in Figure 1 the situation shown, the imaging quality of the specimen 105 (such as a single waveguide) is measured by means of the device 100. The projection unit 115 is positioned in such a way that the object pattern is projected into the entrance pupil 165. The object pattern can also be projected into other regions of the waveguide of the NED module. Therefore, taking the module for AR glasses as an example, the projection unit 115 simulates a real object in the user's environment. In such an application example, the exposure unit of the NED module also only selectively generates a self-luminous structured object pattern, which is detected by the receiving unit 110 as a supplement or alternative to the object pattern of the projection unit 115. For example, the pivoting of the receiving unit 110 is necessary to record the imaging of the object pattern at different field angles of view. In other words, the axial and off-axis imaging qualities are measured in this way. By the lateral movement of the receiving unit 110, the optical parameters and photometric or chromaticity parameters of the optical system or the NED module to be measured can be determined at different positions within the eye socket.

[0058] The device 100 also has a computing unit 150 for electronically controlling the projection unit 115 and the receiving unit 110. In the case of using a corresponding reticle replacement mechanism, the computing unit 150 is used, for example, to control the projection unit 115 to send different object patterns into the optical path. Among them, large-area structures are used to measure the chromaticity or photometric parameters, while structures with sharp lines or edges are used to measure the optical imaging parameters.

[0059] The calculation unit 150 processes the images recorded by the sensors of the receiving unit 110 and calculates the optical imaging parameters and chromaticity or photometric imaging parameters required for the test sample 105 based on the recorded images. For example, the calculation unit 150 controls the image sensor to sequentially record the images of the object structure projected by the sample 105 for each available spectral channel. In this case, the exposure time of the sensor can also be changed. Taking the use of a filter wheel as an example, changing the spectral channel means changing its filter position. For example, for each filter position, one or more images are recorded and transmitted to the calculation unit 150.

[0060] For example, optical parameters and chromaticity or photometric parameters are obtained for each recorded single image or any arbitrary combination of single images. For example, the images sequentially recorded with different exposure times can be combined into one or more high dynamic range (HDR) images. As an alternative, the images sequentially recorded with different spectral weights can be combined into one or more color images. When analyzing the NED complete system or module, the calculation unit 150 is also additionally or alternatively connected to the sample 105. In this case, the projection unit 115 or other projection units of the sample 105 (not shown here) are controlled to display a self-luminous object structure. An example of such a self-luminous object structure is a crosshair pattern or a ring, which is displayed by an LCD or LED display (for illustrative purposes only). In addition, the calculation unit 150 optionally has calibration data for the measuring device, which have been read in during the preparation stage of the measurement. With the aid of these calibration data, imaging errors of the optical devices used in the projection unit 115 or the receiving unit 110, such as the degree of distortion, can be removed from the subsequent measurement data.

[0061] Figure 3 For use in Figures 1 to 2 FIG. at least one of the figures described by way of example. The object structure 300 is designed, for example, to determine the imaging quality of a sample.

[0062] According to this embodiment, the object structure 300 has a dark area 305 and a bright area 310 separated by sharp edges. The object structure 300 is in the shape of a cross. According to this embodiment, the object structure 300 also has a polygonal contour.

[0063] Figure 4 For use in Figures 1 to 2 FIG. at least one of the figures described by way of example of the object structure 300 of the device. The object structure 300 is designed, for example, to determine the imaging quality of a sample.

[0064] According to this embodiment, the object structure 300 has a dark region 305 and a bright region 310 separated by sharp edges. The object structure 300 is circular, especially annular, so according to this embodiment, the object structure 300 has other dark regions 400. According to this embodiment, the object structure 300 also has a polygonal contour.

[0065] Figure 5 It is a schematic diagram of an embodiment of the object structure 300 for a device described by way of example in at least one of the figures such as Figures 1 to 2 . The object structure 300 is designed, for example, to determine the imaging quality of a specimen.

[0066] According to this embodiment, the object structure 300 has a dark region 305 and a bright region 310 separated by sharp edges. According to this embodiment, the object structure 300 is square. According to this embodiment, the object structure 300 also has a polygonal contour.

[0067] Figure 6 It is a schematic diagram of an embodiment of the object structure 300 for a device described by way of example in at least one of the figures such as Figures 1 to 2 . The object structure 300 is designed, for example, to determine the imaging quality of a specimen.

[0068] According to this embodiment, the object structure 300 has a dark region 305 and a bright region 310 separated by sharp edges. According to this embodiment, the object structure 300 also has other dark regions 400 and other bright regions 600. According to this embodiment, the bright regions 310, 600 and the dark regions 305, 400 are arranged diagonally to each other so that all regions 305, 310, 400, 600 converge at a common center point 605 of the object structure 300. According to this embodiment, the object structure 300 also has a circular contour.

[0069] Figure 7 It is a flowchart of an embodiment of a method 700 for determining the imaging quality of an image of a specimen. The method 700 can be implemented, for example, by the Figures 1 to 2 computing unit of one of the devices described. The computing unit is designed, for example, to control the device.

[0070] Accordingly, method 700 includes step 705: using a projection unit to output light, for example, with an adjustable duration, to project at least one luminous and / or illuminating object structure onto a specimen. In addition, method 700 further includes step 710: using a receiving unit to receive light beams that are transmitted through the specimen or reflected at the specimen, and these light beams represent at least one image; and step 715: simultaneously evaluating a first light parameter and a second light parameter of the light beams that are transmitted through the specimen or reflected at the specimen. The first light parameter represents at least one optical light parameter, and the second light parameter represents at least one chromaticity or photometric light parameter, so as to simultaneously determine the imaging quality of at least one image using a calculation unit. In the receiving step 710, it is also possible to optionally receive other light beams that are transmitted through the specimen or reflected at the specimen, and these other light beams represent at least one other image. This means that in the evaluation step 715, other first light parameters (representing at least one other optical light parameter) and other second light parameters (representing at least one other chromaticity light parameter) of the other light beams are simultaneously evaluated to determine the other imaging quality of the other images. In particular, the images and the other images are acquired with different exposure times respectively for this purpose.

[0071] According to this embodiment, method 700 may further optionally include step 720: before the evaluation step 715, using predetermined calibration data to compensate for and correct imaging errors, such as distortion; and / or step 725: after the evaluation step 715, combining the images and the other images into an overall image. For example, combining them into an overall HDR image in the case of different exposure times, or combining them into a complete color image in the case of different spectral settings. Among them, parameters are determined, for example, for a single image or an overall image.

[0072] In other words, method 700 for measuring the imaging quality of an optical system or module of an NED system is described, where in the output step 705, a luminous and / or illuminating object structure is projected, and this object structure is transmitted through or reflected by the optical system or module to be measured. In the receiving step 710, the receiving unit receives one or more images of the transmitted or reflected object structure with different spectral settings of the detector. In the evaluation step 715, the calculation unit simultaneously determines one or more optical parameters and chromaticity or photometric parameters of the optical system or module to be measured based on the one or more images. Optionally, the exposure time of the detector is adjustable, and multiple images acquired with different exposure times can be combined into an overall HDR image by means of the calculation unit. In addition, in the combining step 725, the images acquired with different spectral settings are combined into an overall image by means of the calculation unit, and it is possible to select to determine optical parameters and chromaticity or photometric parameters for each single image and / or the combined overall image.

[0073] Figure 8 For a block diagram of a calculation unit 150 according to an embodiment, the calculation unit is used as Figures 1 to 2The device described by way of example in at least one of the figures. Accordingly, the calculation unit 150 is designed to control and / or implement a method for imaging quality determination of at least one image of a measurement specimen as described in Figure 7 Accordingly, the calculation unit 150 has an output unit 800, an input unit 805, and an evaluation unit 810. The calculation unit 150 may also optionally have a compensation unit 815 and / or a merging unit 820.

[0074] The output unit 800 is designed to output light using a projection unit in order to project at least one luminous and / or illuminating object structure onto the specimen. The input unit 805 is used, for example, to input the light transmitted through the specimen or reflected at the specimen and received by the receiving unit of the device, i.e., for example, a first light parameter 825 and a second light parameter 830 of the light beam. The evaluation unit 810 is used to simultaneously evaluate the first light parameter 825 (representing at least one optical light parameter) and the second light parameter 830 (representing at least one chromaticity or photometric light parameter) of the light beam transmitted through the specimen or reflected at the specimen in order to simultaneously determine the imaging quality of at least one image. Optionally, the input unit 805 is also used to input other light transmitted through the specimen or reflected at the specimen and received by the receiving unit of the device, i.e., for example, other first light parameters 831 (representing at least one other optical light parameter) and other second light parameters 832 (representing at least one other chromaticity or photometric light parameter) of other light beams. Accordingly, the evaluation unit 810 is used to simultaneously evaluate the other first light parameter 831 and the other second light parameter 832 of the other light beams to determine the other imaging quality of other images. In particular, the images and the other images are acquired with different exposure times, respectively.

[0075] Furthermore, the compensation unit 815 is optionally designed to compensate or correct imaging errors using predetermined calibration data 835. The merging unit 820 is used, for example, to merge the image and the optionally only other image to obtain an overall image.

[0076] In summary, regarding the type of optical system to be measured, it should be noted that the intended use of the device for which a patent is sought is as a module for an AR / VR system. Specifically, these modules can be a single waveguide or a waveguide with its own projector (e.g., for AR glasses). The measurement system itself, for example, only has a projection device and a receiving device. Both can be pivoted or moved, for example. In particular, the second projection unit is not a general component of the measurement system. As Figure 1 described, the second projection unit only exists when measuring the NED module. Regarding Figure 1 the system shown, in an application example, the transmission effect of the waveguide on the image generated by the NED projector (e.g., AR glasses) can be measured and compared with the presentation effect of the real environment.

[0077] For example, when comparing a spectral filter and an ND filter, it is important to distinguish between the two filters in the receiving unit. The spectral filter ensures that it is set to the desired wavelength range, especially in chromaticity measurements. Examples are the V(λ) filter for adapting to the spectral sensitivity of the human eye or the Bayer pattern (weighted distribution of RGB filters) of a CCD camera. The ND filter reduces the light intensity and is not affected by the spectrum. Both filters can be used in practice.

[0078] When adjusting the field of view angle and the beam cross-section, it should be noted that, for example, at the receiving end, there is no need to adjust the field of view angle of the beam. Here, an optical device with a suitable field of view angle needs to be selected, such as a conoscopic lens for a large field of view angle. However, for example, if it is necessary to simulate the human eye iris, adjusting the beam cross-section is helpful, so an adjustable aperture stop 144 is required. At the projection end, it may be necessary to adjust both the cross-section and the field of view angle of the beam. Therefore, the Figure 1 field stop 181 in is proposed. (The image of the field stop is a hatch.) Adjusting the beam cross-section helps to avoid overexposure of the specimen and minimize possible interference factors such as stray light. The field of view angle should be adjustable in order to obtain the desired waveguide input coupling angle, because not every possible total internal reflection is necessarily required here.

Claims

1. An apparatus (100) for determining the imaging quality of at least one image of a specimen (105), characterized in that, The device (100) comprises: at least one projection unit (115) for outputting light (120) in the direction of the specimen (105) in order to project at least one luminous and / or illuminating object structure (300) onto the specimen (105); an optical receiving unit (110) for receiving light beams (130) that have passed through the specimen (105) or have been reflected at the specimen (105), which beams represent at least one image of the projected object structure (300), wherein the receiving unit (110) has optical means (135) and an optical detector (140); a support unit (145) for holding the specimen (105) to be tested, wherein the support unit (145) is arranged between the projection unit (115) and the optical receiving unit (110); and a computing unit (150) for simultaneously evaluating a first optical parameter (825) and a second optical parameter (830) of the light beams (130) that have passed through the specimen (105) or have been reflected at the specimen (105) and received by the receiving unit (110), the first optical parameter representing at least one optical light parameter and the second optical parameter representing at least one chromaticity and / or photometric light parameter, in order to determine the imaging quality of at least one image of the specimen (105), wherein the computing unit (150) is connected to the projection unit (115), the receiving unit (110) and / or the support unit (145).

2. The device (100) according to claim 1, characterized in that, The detector (140) of the receiving unit (110) has a plurality of spectral channels (141) and at least one image sensor (142), in particular, wherein the detector (140) of the receiving unit is implemented as a focusable camera.

3. The device (100) according to any one of the preceding claims, characterized in that, The receiving unit (110) has optical means (135) that are diffraction-limited over the entire detectable field angle.

4. The device (100) according to claim 3, characterized in that, The optical means (135) has replaceable components and at least one adjustable optical aperture stop (144) for adjusting the geometric properties of the light beams entering the optical means (135).

5. The device (100) according to any one of the preceding claims, characterized in that, The projection unit (115) is designed as a focusable or non-focusable collimator, which in particular has at least one monochromatic illuminating and / or polychromatic illuminating reticle element (182).

6. The device (100) according to claim 5, characterized in that, The projection unit (115) has at least one reticle element (182) containing a plurality of different object structures (300), or the projection unit (115) has a replacement mechanism for successively feeding different reticle elements (182) having different object structures (300) into the optical path of the light (120), in particular, wherein these object structures (300) represent large-area elements, sharp edges and / or lines.

7. The device (100) according to any one of the preceding claims, characterized in that, These object structures (300) are produced by or can be produced by self-luminous elements, and / or, wherein the projection unit (115) has a projection aperture stop (180) and / or a projection field stop (181).

8. The device (100) according to any one of the preceding claims, characterized in that, It has a movable first goniometer (146) and a movable second goniometer (147), the first goniometer is connected to the projection unit (115), and the second goniometer is connected to the receiving unit (110), wherein the first and second goniometers (146, 147) are used to move the projection unit (115) and the receiving unit (110) independently of each other around a defined pivot point in at least two different directions. In particular, the first goniometer (146) and / or the second goniometer (147) can be translated relative to the specimen (105) in at least three spatial directions.

9. A method (700) for determining the imaging quality of at least one image of a specimen (105) using a device (100) as described in any of the preceding claims, characterized in that, The method (700) comprises the following steps: Outputting (705) light (120) using the projection unit (115) so as to project at least one luminous and / or illuminating object structure (300) in the direction of the specimen (105); Receiving (710) by the receiving unit (110) the light beams (130) transmitted through or reflected at the specimen (105) of the light (120), these light beams representing at least one image; and Simultaneously evaluating a first light parameter (825) and a second light parameter (830) of the light beams (130) transmitted through or reflected at the specimen (105) of the light (120), the first light parameter representing at least one optical light parameter, and the second light parameter representing at least one chromaticity or photometric light parameter, so as to simultaneously determine the imaging quality of at least one image using the calculation unit (150).

10. The method (700) according to claim 9, characterized in that, In the receiving step (710), other light beams (171) transmitted through or reflected at the specimen (105) of other light (160) are received, these other light beams representing at least one other image, wherein in the evaluation step (715), other first light parameters (831) and other second light parameters (832) of these other light beams (171) are simultaneously evaluated, the other first light parameters representing at least one other optical light parameter, and the other second light parameters representing at least one other chromaticity or photometric light parameter, so as to determine the other imaging quality of the other image. In particular, the image and the other image are acquired with different exposure times respectively.

11. The method (700) according to claim 10, wherein, A step (725) of combining the image and the other image into an overall image after the evaluation step (715).

12. The method (700) according to any one of claims 9 to 11, characterized in that, A step (720) of compensating for imaging errors using predetermined calibration data (835) before the evaluation step (715).

13. A computing unit (150) for a device (100) as claimed in any one of claims 1 to 8, characterized in that, The calculation unit (150) is designed to control and / or implement the steps (705, 710, 715, 720, 725) of the method (700) as claimed in any one of claims 9 to 12 in the corresponding units (800, 805, 810, 820).

14. A computer program, which is designed to implement and / or control the steps (705, 710, 715, 720, 725) of the method (700) as claimed in any one of claims 9 to 12.

15. A machine-readable storage medium, on which the computer program according to claim 14 is stored.

Images