Apparatus having a scanning device

Abstract

An apparatus (10, 10') for inspecting an object or scanning an eyeball (1) includes a scanning device (2, 2a) having a reflective surface (3) to which at least one ray (4) emitted from a light source (8) can be guided, wherein a reflected ray (5a) traveling from the reflective surface (3) toward the incident ray (4) can be rotated over a first angular region (6a) using the scanning device (2), and is characterized in that an optical means is provided, which allows a straight-traveling reflected light (5a) to be rotated over a second angular region (6c) larger than the first angular region (6a) after passing through the means. (Figure 2)

Description

Technical Field

[0001] The present invention relates to an apparatus according to the generic concept of claim 1.

Background Art

[0002] An apparatus for scanning an eyeball generally includes a scanning device having a scanning surface or a reflecting surface, and incident light rays can be guided to the reflecting surface. At that time, using the scanning device, the light rays reflected from the reflecting surface toward the incident light rays can be pivoted over an angular region, a so-called scanning angle. By scanning with such light rays, a structure can be examined.

[0003] In this background, a confocal laser scanning system using light rays and a point detector is already known. Furthermore, a laser scanning system having line irradiation and line detection is known.

[0004] Conventional confocal laser scanning systems are limited with respect to light intensity and speed. This is because the system characteristics are somewhat interdependent with the scanning speed, the scanning angle, and the scanning surface, and cannot be arbitrarily improved.

[0005] Scanning devices having a large scanning surface and a scanning angle are often relatively slow in operation. On the contrary, small scanning devices having a smaller scanning angle are often fast in operation.

[0006] The product of the scanning surface or the reflecting surface and the scanning angle is decisive for the light intensity and cannot be increased by the optical transmission ratio either. Exactly in a wide-angle system, due to the above, the light intensity or the speed may be limited. A scanning device with a small scanning angle uses a long focal length to generate a large intermediate image. In this way, the requirement for the occupied space of the optical system increases.

[0007] Laser scanning systems with line illumination and line detection share focus in only one axis. This further reduces image quality, increases the cost of the optics, and requires a highly sensitive line camera. If multiple detectors and light sources are used, or if ray expansion means are employed, additional optical elements are required, which further increases costs. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Therefore, the fundamental objective of this invention is to provide a scanning device that can achieve a large total scanning angle with as few problems as possible, especially without reducing the scanning surface or lowering the speed. [Means for solving the problem]

[0009] The present invention solves the above-mentioned problems with the features of claim 1.

[0010] First, this invention found a need for a wide-angle scanning system, particularly one with a wide angle of ±30° or more in front of the eyeball, strong light, high speed, and extremely good image quality. It also found that this wide-angle scanning system should be as compact as possible so that it can be used in a manner suitable for operation. Furthermore, it found a need for a high-speed scanning system with a narrow scanning angle.

[0011] According to the present invention, an apparatus for inspecting an object or scanning an eyeball must include at least one scanning device having a reflective surface to which at least one ray emitted from a light source can be guided. In this case, the reflected ray traveling from the reflective surface toward the incident ray can be rotated over a first angular region using the scanning device.

[0012] In this invention, an optical means is provided so that a straight-traveling reflected light ray can be rotated over a second angular region after passing through the means. In this case, the second angular region is larger than the first angular region. In this way, the light ray, especially the laser ray, travels through the same scanning plane or reflective surface of the scanning device multiple times in a loop-like manner, but from various angles, so that the total scanning angle is increased.

[0013] The direction of the light ray is changed via a light guide component, and the light ray is projected back onto the same scanning or reflective surface, or the scanning device is projected almost optically onto itself. If the scanning surface remains the same, the scanning angle increases, preferably by a factor of two. Thus, the product of the angle multiplied by the surface becomes four times, thereby enabling a system with higher light intensity or higher light speed.

[0014] The apparatus described herein allows for greater freedom in scanner selection. For wide-angle systems, a wider scanning angle provides a more detailed, one-to-one image. This is advantageous when certain optical aberrations occur based on optical symmetry. A lower optical transfer ratio results in a shorter focal length, which again works to the advantage of space-saving requirements.

[0015] The second angular region may be twice as large as the first angular region. This effectively expands the entire scanning angle, and its size is optimized.

[0016] The reflected light ray traveling in a straight line from the reflective surface may be returned to the reflective surface by multiple optical means, and the returned ray may be rotated over a second angular region from that location. The ray rotated over the second angular region is a ray that has been scanned twice. The scanning device or its scanning surface is reoriented mostly through optical components and projected onto itself. The light to be scanned or detected travels through the scanning device multiple times, preferably over the same position or the same surface, and is therefore scanned multiple times. This increases the total scanning angle of the scanning system. In this case, the beam diameter of the ray does not change, and therefore its light intensity is kept almost constant. Specifically, the beam diameter remains the same, and the scanning angle increases, resulting in an increase in light intensity. Therefore, by using optical transfer means, the product of the scanning angle and the scanning surface increases.

[0017] The light rays incident from the light source, which are nearly stationary rays, can be guided to the reflective surface at a different angle than the returned rays. By selecting a different angle, the size of the total scanning angle can be adjusted.

[0018] Reflected light rays traveling in a straight line from a reflective surface may pass through optical means, collide with the reflective surface again, and then be guided from this reflective surface to an optical device or to the object being examined for scanning. Light rays with a wide scanning angle can pass through the optical device or the object being examined. The object being examined can be inspected using certain wide-angle objective lenses.

[0019] A detector or a single detector may be provided, which detects light rays or signals of such reversed light rays traveling backward from the optical device or the object under test. When using only one detector, the device can be made compact. The reversed light rays may be scattered and / or reflected by the object under test.

[0020] Light rays traveling backward from the object being tested can be guided to a reflective surface, guided from that reflective surface through optical means, guided again from that optical means to the reflective surface, and may be guided from this reflective surface to a detector. This allows the object being tested to be scanned with high light intensity.

[0021] The steady-state light rays exiting the light source and the light rays traveling in the opposite direction to the detector may be guided parallel to and / or on the same straight line. This allows for a compact configuration of the device and eliminates the need for deflection means. Furthermore, the straight-traveling and reverse-traveling light rays can be interfered with each other without problems, and in some cases, OCT images can also be detected.

[0022] The optical means may include at least two deflection mirrors. These multiple deflection mirrors can reliably change the direction of light rays around multiple angles with as little loss of intensity as possible. By appropriately positioning and spacing the multiple deflection mirrors relative to each other, the entire scanning angle can be easily adjusted.

[0023] The optical means may include at least two or four lenses. Each pair of lenses can be arranged to share a focal point with respect to each other, thus enabling a focal-sharing configuration of the device.

[0024] The optical means may include at least one curved mirror. Such a mirror can, on the one hand, change the direction of light and at the same time focus the light to a focal point.

[0025] The scanning device may include an X-direction scanning device, or may be configured solely as an X-direction scanning device. In this case, a Y-direction scanning device is also provided. This allows the object to be scanned in the planar direction, and therefore in the transverse direction. A two-dimensional display of the inspected object can be created.

[0026] The Y-direction scanning device may be configured as a deflection mirror. By means of this deflection mirror, the reflected light beam traveling straight is reflected back to the reflecting surface as a return light beam after being reflected by two preceding deflection mirrors, and is guided from the reflecting surface to an optical device or a test object, so that this object can be scanned in the Y direction.

[0027] With this configuration, two scanning devices can be used simultaneously, and the object can be scanned in the X direction and the Y direction simultaneously. In particular, with this configuration, the X scanner and the Y scanner or the scanning devices are projected on top of each other, resulting in an ideal scanning pupil.

[0028] The light hitting the Y-direction scanning device may be guided by a third lens before hitting the Y-direction scanning device, and the light exiting from the Y-direction scanning device and traveling forward may be guided by a fourth lens. Thereby, the third lens can be arranged to share a focus with the first lens, and the fourth lens can be arranged to share a focus with the second lens.

[0029] In this context, at least two lenses may be arranged to share a focus with each other and / or to share a focus with each other while sandwiching one deflection mirror or two deflection mirrors therebetween. By using deflection mirrors, the lenses arranged to share a focus can be arranged relative to each other in a particularly compact manner. The overlapping foci of the two lenses used can be immediately beside the deflection mirror or immediately above the deflection mirror.

[0030] With the device described in this specification, the scanning angle can be adjusted through a 4f mapping of the scanning surface onto itself. Another scanning axis achievable by the Y-direction scanning device can be incorporated into this device and projected onto the X-direction scanning device. Therefore, an optimal scanning pupil for the entire scanning system without optical deviation is obtained. A small intermediate image can be used for position feedback. Thereby, in some cases, the main optical system or the optical device can be simplified. Moreover, with the device described in this specification, the image quality is improved by a stronger light intensity.

[0031] Using the apparatus described herein, it is possible to achieve four times the amount of light leakage from the eyeball being examined, enabling double scanning. The numerical aperture is improved, or the optical resolution is improved. The beam diameter can be increased, resulting in less lens reflection. The apparatus described herein requires only one detection; there is no need to combine multiple individual images. There is no need to superimpose individual images. For the same resolution, integration time at the detector can be reduced. Multiple optical components can be introduced into the optical path. The scanning angle can be expanded by multiple scans.

[0032] The drawing shows the following: [Brief explanation of the drawing]

[0033] [Figure 1] Figure 1 is a schematic diagram of the functional configuration of a device equipped with a stationary or motionless scanning device. [Figure 2] Figure 2 shows the functional configuration according to Figure 1. The scanner's deflection is schematically shown to illustrate the full scanning angle. [Figure 3] Figure 3 shows the functional configuration of another device. It implements an additional Y-axis scanning axis, and the scanning direction is stationary. [Figure 4] Figure 4 shows the functional configuration according to Figure 3, with an additional Y-axis scanning axis. Scanner deflection is schematically shown to illustrate the full scanning angle. [Modes for carrying out the invention]

[0034] Figures 1 and 2 schematically show a device 10 for inspecting an object or scanning an eyeball 1. The device includes a scanning device 2 which has a reflective surface 3 to which at least one light ray 4 emitted from a light source 8 can be guided. When the reflective surface 3 is vibrated, the reflected light ray 5a traveling from the reflective surface 3 toward the incident light ray 4 can be rotated over a first angular region 6a using the scanning device 2.

[0035] In this regard, the incident light ray 4 can be reflected and rotated over the first angular region 6a as a straight-traveling reflected light ray 5a. This rotation is shown based on the scanner deflection schematically shown in Figure 2. The straight-traveling reflected light ray 5a is shown as a solid white line. In this regard, the straight-traveling reflected light ray 5a is a ray that has been scanned once.

[0036] An optical means is provided, which allows reflected light 5a traveling in a straight line to rotate over a second angular region 6c that is larger than the first angular region 6a after passing through the means. Specifically, the second angular region 6c is twice the size of the first angular region 6a and represents the entire scanning angle of the device. This is similarly illustrated in Figure 2.

[0037] In this regard, the ray 5a that rotates over the second angular region 6c is a ray that has been scanned twice. This is because the ray is first reflected from the reflective surface 3, guided to the optical means, then returned to the same location on the reflective surface 3, and then rotated from that location over the second angular region 6c, i.e., the entire scanning angle, towards the optical device 15, particularly the main optical system, or the object under examination.

[0038] In this regard, Figure 2 specifically shows how the first angular region 6a can transition to the second angular region 6c when the reflective surface 3 of the scanning device 2 vibrates. Rays 5a that strike and leave the reflective surface 3 at various angles are schematically shown with various terminations, including rhombuses, circles, and arrowheads.

[0039] Any reflected ray 5a traveling from the reflective surface 3 toward the optical means can be returned from the optical means to the reflective surface 3 as a returned ray 5a, and can be rotated from the reflective surface over a second angular region 6c. The above is indicated by the use of solid white lines to represent each returned ray 5a.

[0040] In this regard, the straight-traveling reflected ray and the reverse-traveling ray 5a are first scanned rays, and then, as they rotate across the second angular region 6c, they transition into rays 5a that have been scanned twice.

[0041] The light ray 4 incident on the reflective surface 3, which can also be described as a steady ray, may be guided to the reflective surface 3 at a different angle than the returned light ray 5a. The reflected light ray 5a, which leaves the reflective surface 3 and travels along it, is guided almost in a loop, then leaves the reflective surface 3, passes through the optical means, and then strikes the reflective surface again, from which it is guided to the optical device 15 or the object under test.

[0042] The reflected light 5a that exits the reflective surface 3 and travels forward is guided from the reflective surface 3 to the optical device 15 or the object to be examined, and scans the object.

[0043] Specifically, only a detector 7 is provided, and this detector detects the light ray 5b or the signal of the back-propagating light ray 5b that is propagating backward from the optical device 15 or the object under test. The back-propagating light ray 5b is a light ray that has been backscattered or reflected from the object under test.

[0044] Light rays traveling backward from the optical device 15 or the object being examined are indicated by white dashed lines.

[0045] The retro-propagating rays 5b that strike the reflective surface 3 at various angles and then deviate from it are schematically shown with various terminations, including rhombuses, circles, and arrowheads.

[0046] Each of the retro-propagating rays 5b can be guided to the reflective surface 3, guided from the reflective surface through optical means, guided again from the optical means to the reflective surface 3, and guided from this reflective surface to the detector 7.

[0047] In this way, if a reference arm is present, the structure can be examined by interfering the ray 4 generated from the light source 8 with the ray 5b traveling in the reverse direction. The ray 4 traveling out of the light source 8 and the ray 5b being sent back to the detector 7 can be guided to be parallel and / or colinear.

[0048] Figures 1 and 2 show that the optical means is minimal and includes two deflection mirrors 16a and 16b. The deflection mirrors 16a and 16b change the direction of the reflected light rays 5a traveling from the reflective surface 3 toward the optical means by two angles or angles, and guide these reflected light rays back to the reflective surface 3 as return rays 5a.

[0049] The optical device further includes two lenses 12a and 12b. These lenses are arranged to share a focal point such that their focal points overlap with each other between the deflection mirrors 16a and 16b. Thus, the device exhibits a focal-sharing configuration. Specifically, only two lenses are provided: the first lens 12a and the second lens 12b.

[0050] Figures 3 and 4 show another apparatus 10' for inspecting an object or scanning an eyeball 1. This apparatus includes a scanning device 2 equipped with an X-direction scanning device 2a having a reflective surface 3, which can guide at least one ray 4 emitted from a light source 8 (not shown) to the reflective surface. The scanning device 2, 2a can be used to rotate the reflected ray 5a traveling from the reflective surface 3 toward the incident ray 4 over a first angular region 6a.

[0051] The reflected light rays 5a traveling in a straight line are shown as solid white lines, as in Figure 2.

[0052] An optical means is provided, and using this optical means, a straight-traveling reflected light ray 5a can be rotated over a second angular region 6c that is larger than the first angular region 6a after passing through the optical means.

[0053] Specifically, the second angular region 6c is twice the size of the first angular region 6a and represents the entire scanning angle of this device.

[0054] The reflected light ray 5a, which travels from the reflective surface 3 in the direction of the optical means, can be returned to the reflective surface 3 as a return ray 5a from the optical means, and can be rotated over a second angular region 6c from the reflective surface. The return ray 5a is similarly represented by a solid white line to indicate the above.

[0055] The light ray 4 incident on the reflective surface 3 may be guided to the reflective surface 3 at a different angle than the returned light ray 5a. The light ray 5a is guided almost in a loop, then leaves the reflective surface 3, passes through the optical means, and then strikes the reflective surface again, from which it is guided to the optical device 15 or the object under test.

[0056] The reflected light rays 5a that exit the reflective surface 3 and travel forward are guided back from the reflective surface 3 to the optical device 15 or the object under test as returned light rays 5a after passing through the optical means, and the object under test is scanned.

[0057] Specifically, only one detector 7 (not shown) is provided, and this detector detects the light ray 5b or the signal of the retrograde light ray 5b traveling backward from the optical device 15 or the object being tested.

[0058] The light rays 5b traveling backward from the optical device 15 or the object under test are indicated by white dashed lines. Each backward-traveling light ray 5b can be guided to the reflective surface 3, guided from the reflective surface through the optical means, guided again from the optical means to the reflective surface 3, and guided from the reflective surface to the detector 7.

[0059] In this way, the structure can be examined by interfering the light ray 4 generated from the light source 8, which can also be described as a steady ray, with the light ray 5b that is traveling in the reverse direction. The light ray 4 traveling out of the light source 8 and the light ray 5b that is sent back to the detector 7 can be guided to be parallel and / or on the same line.

[0060] Figures 3 and 4 show that the optical means includes two deflection mirrors 16a and 16b. These two deflection mirrors change the direction of the straight-traveling reflected light ray 5a and the reverse-traveling light ray 5b by two angles or angles.

[0061] The direction of the reflected light rays 5a traveling from the reflective surface 3 toward the optical means is changed from the first deflection mirror 16a through the first lens 12a to the second deflection mirror 16b. The reflected light rays 5a traveling away from the second deflection mirror 16b are guided through another third lens 12c.

[0062] The first lens 12a and another third lens 12c are positioned to share a focal point such that their focal points overlap right next to or just above the second deflection mirror 16b.

[0063] The reflected light rays 5a exiting from another third lens 12c are directed to the Y-direction scanning device 2b. The Y-direction scanning device is assigned to and / or electronically connected to the scanning device 2 for simultaneous control. Thus, the scanning device 2 includes an X-direction scanning device 2a and a Y-direction scanning device 2b. The X-direction scanning device 2a operates faster than the Y-direction scanning device 2b.

[0064] The Y-direction scanning device 2b is configured as a deflection mirror. This deflection mirror reflects the straight-traveling reflected light 5a back to the reflective surface 3 after being reflected by two preceding deflection mirrors 16a and 16b, and guides it from the reflective surface to the optical means 15 or the object under inspection, allowing the object to be scanned in the Y direction as well.

[0065] Therefore, both the direction of the straight-traveling reflected ray 5a and the direction of the reverse-traveling ray 5b are changed by three angles or corners.

[0066] The reflected light ray 5a that exits the Y-direction scanning device 2b first passes through the fourth lens 12d, then the second lens 12b, and is then guided back to the reflective surface 3 as the returned light ray 5a.

[0067] The second lens 12b and the fourth lens 12d are arranged to share a focal point such that their focal points overlap with each other. Next, the return ray 5a is guided from the X-direction scanning device 2a to the optical device 15 or the object under examination.

[0068] In relation to this, Figure 4 shows the deflection of the scanner of scanning device 2, similar to Figure 2.

[0069] In Figures 3 and 4, the principle configuration of the apparatus shown in Figures 1 and 2 is extended with an additional scanning mirror, i.e., the Y-direction scanning device 2b, at its center. Since the Y-direction scanning device 2b is projected onto the X-direction scanning device 2a via a 4f map, an optimal scanning pupil without optical shift is obtained. Furthermore, a complete, compact XY intermediate image exists, and this intermediate image can be used for position feedback.

[0070] Figures 2 and 4 show the functional configuration of the device based on the schematicly indicated scanner vibration.

[0071] The mapping does not necessarily have to be performed via an optical lens as described herein. Instead, other optical components, such as a curved mirror, can be used.

[0072] The principle of the apparatus described herein is as follows:

[0073] The light ray 4 strikes the scanning device 2 and is deflected or scanned in various ways by this scanning device. The scanning surface or the impact reflection surface of the scanning device 2 is projected onto itself via a 4f map including two lenses 12a, 12b and two deflection mirrors 16a, 16b.

[0074] Due to the deflection mirrors 16a and 16b, the returning light ray 5a strikes the scanning device 2 at an angle different from the angle of the straight-traveling reflected light ray 5a. Therefore, the light ray 5a travels through the same scanning surface twice, thereby doubling the total scanning angle 6c.

[0075] The ability to increase the total scanning angle 6c while keeping the ray diameter the same using this method offers several advantages. In this way, using the gain, i.e., the product of angle and plane, it is possible to realize a high-speed system with a higher scanning speed or higher optical efficiency.

[0076] The above will be clarified based on the following other examples. These examples will illustrate the effects of the invention described herein based on existing products. Example 1: Improvement of light intensity / image quality CRS 4kHz, 10mm scanning plane, + / -10 degree optical scanning angle 60°, 4kHz scanning system Conventional scanners vs. dual-lens scanners Frequency X-direction scanner [kHz] 4 4 Scanning surface diameter [mm] 9 9 Total scanning angle Optical [degrees] 20 40 Target angle [degrees] of the object: 60 60 Optical transfer ratio 3 1.5 The pupil of the eyeball has a diameter of 3 to 6 inches. Example 2: Improving scanning speed 30°, 12kHz scanning system Conventional scanners vs. dual-lens scanners Frequency X-direction scanner [kHz] 8 12 Scanning surface diameter [mm] 5 5 Optical total scanning angle [degrees]: 20 20 (2 × 10°) Target angle [degrees] of the object: 30 30 Optical transfer ratio 1.5 1.5 Pupil diameter in the eyeball: 3.33 3.33

[0077] The technologies described herein can be used in wide-angle systems. The high light intensity obtained through these technologies improves image quality. Alternatively, it is possible to increase the scanning speed. The aforementioned technical features are important prerequisites for the operational suitability of the device. [Explanation of symbols]

[0078] 1. Eyeball or object to be examined 2 Scanning device X-direction scanning device of 2a 2 2b 2 Y-direction scanning device 3 2, 2a reflective surface 8 rays of light incident on 4 3 5a A ray of light that exits from 3, moves forward, and is sent back to 3. 5a Rays swirling through 3 to 6c 5b Ray traveling backward from 1 6a 5a's first angular region 6c 5a's second angular region 7 Detectors 8 light source 10, 10' device 12a~12d: Lens 1 to Lens 4 15 Optical device or main optical system 16a First deflection mirror 16b Second deflection mirror

Claims

1. A device (10, 10') for inspecting an object or scanning an eyeball (1), comprising a scanning device (2, 2a) having a reflective surface (3) toward which at least one light ray (4) emitted by a light source (8) is directed, wherein the reflected light ray (5a) emitted by the reflective surface (3) by the incident light ray (4) is rotatable over a first angular region (6a) by the scanning device (2), The apparatus is characterized in that it is provided with an optical means, and after the emitted reflected light ray (5a) passes through the means, it can be rotated by the optical means over a second angular region (6c) that is larger than the first angular region (6a).

2. The apparatus according to claim 1, characterized in that the second angular region (6c) is twice the size of the first angular region (6a).

3. The apparatus according to claim 1 or 2, characterized in that the reflected light rays (5a) emitted from the reflective surface (3) are guided from the optical means to return to the reflective surface (3) and are swirled from the reflective surface over the second angular region (6c).

4. The apparatus according to claim 3, characterized in that the incident light ray (4) is guided to the reflective surface (3) at a different angle than the light ray (5a) that has returned to active.

5. The apparatus according to any one of claims 1 to 4, characterized in that the reflected light (5a) emitted after passing through the optical means is guided from the reflective surface (3) to the optical device (15) or the object to be examined, and scanned therein.

6. The apparatus according to claim 5, wherein a detector (7) or only one detector (7) is provided, and the detector detects a ray (5b) returning from the optical device (15) or the object to be examined, or detects a signal of the returned ray (5b).

7. The apparatus according to claim 6, characterized in that the reflected light ray (5b) is guided to the reflective surface (3), from there the light ray is guided by the optical means, and from there the light ray is guided again to the reflective surface (3), and from the latter to the detector (7).

8. The apparatus according to claim 7, characterized in that the emitted light ray (4) and the light ray (5b) returning to the detector (7) are guided in a parallel and / or collinear manner.

9. The apparatus according to any one of claims 1 to 8, characterized in that the optical means includes at least two deflection mirrors (16a, 16b).

10. The apparatus according to any one of claims 1 to 9, characterized in that the optical means includes at least two lenses (12a, 12b) or four lenses (12a, 12b, 12c, 12d).

11. The apparatus according to any one of claims 1 to 10, characterized in that the optical means includes at least one curved mirror.

12. The apparatus (10') according to any one of claims 1 to 11, characterized in that the scanning device (2) includes or is configured to include an X-direction scanning device (2a), and is further provided with a Y-direction scanning device (2b).

13. The apparatus according to claim 12, characterized in that the Y-direction scanning device (2b) is designed as a deflection mirror, thereby guiding the emitted reflected light ray (5a) back to the reflective surface (3) after being reflected by two preceding deflection mirrors (16a, 16b), and from there guiding it to the optical device (15) or the object to be examined, and scanning it in the Y direction.

14. The apparatus according to claim 12 or 13, characterized in that light incident on the Y-direction scanning device (2b) is guided through a lens (12c) or a third lens (12c), and light emitted from the Y-direction scanning device (2b) is guided through another lens (12d) or a fourth lens (12d).

15. The apparatus according to any one of claims 1 to 14, characterized in that at least two lenses (12a, 12b, 12c, 12d) are arranged confocally with respect to each other, and / or are arranged confocally with respect to each other with a deflection mirror (16b) or two deflection mirrors (16a, 16b) in between.

Images