Device for capturing long exposure images

Abstract

The present invention relates to the field of requiring long exposure of images, for example when photographing blurred objects. The device comprises an image composition unit, an image capture unit, and a shutter. The device further comprises an additional shutter connected to at least one noise detector via a control unit.

Description

[Technical field]

[0001] The present invention relates to the field of capturing images requiring long exposure times, for example when photographing blurry objects. [Background technology]

[0002] There are several fields in which long exposures are necessary to capture images. For example, obtaining an image in astronomy can require exposures of hundreds of seconds. Long exposures are also required in microscopy. In particular, imaging dim fluorescent objects in fluorescence microscopy can require the use of exposures of tens of seconds.

[0003] Currently, capturing images of blurred objects is carried out using photosensitive arrays, in particular based on CCD (Charge Coupled Device) technology. The photosensitive array is an electronic device that integrates an electric charge during an exposure. When the integration process is finished, the accumulated charge drops. The next exposure, even if after a short time, means to start the charge integration process from the initial level, so the operation of the photosensitive array must not be interfered with during the entire exposure time.

[0004] The risk of interference in obtaining an image increases during long exposures. The interference can be of various nature. They can be related to disturbances or vibrations of the image capture device, i.e. the optical device, for example due to ground tremors, such as earthquake ground vibrations. They can be related to light pollution, for example due to pulsed illumination devices, or due to satellites, bright objects moving into the telescope's field of view, etc.

[0005] The primary shutter of such optical devices does not facilitate the clearance of disturbances. It is usually not a fast shutter, but rather is intended to open and close the corresponding image capture unit at the beginning and end of the capture process. As mentioned above, it serves no purpose to interfere with the operation of the photosensitive array for the clearance of disturbances, because the integrated charge would be lost.

[0006] Applicant's research did not reveal any sources containing a solution for this problem, however the following approaches are known in the art.

[0007] Russian Patent Invention No. 2662907 (RU2662907) IPC G02B 23 / 00, published on July 31, 2018, discloses a method for reducing light pollution of an astronomical device by light from an outdoor lighting device. The method includes time separation of the operating cycles of the astronomical device and the lighting device. A pulsed light beam is formed with a frequency of 300-1000 Hz and a duty ratio of 2-10, and interfering with the light beam on the photosensitive array of the astronomical device is performed in a pulse mode matched by frequency and in reverse phase with the formed light beam.

[0008] Russian Patent Application 93005699 (RU93005699) IPC G01J 1 / 44, published on 27 January 1995, discloses a "Device for protection of photo-receiver against light interferences" with a lens and a beam splitter arranged behind the lens. The beam splitter ensures the operation of two optical channels, each with a photo-receiver. The device features an optical element arranged in one of the channels between the beam splitter and the photo-receiver. The optical element has a variable attenuation ratio and comprises a lattice mesh made of control electrodes. The other channel comprises a neutral optical filter between the beam splitter and the photo-receiver. The photo-receiver is connected to a processor via an adapter device. A control unit can be connected to the same processor. The control unit is coupled to the optical element with the variable attenuation ratio. The device may be used in various areas of science and technology, such as aeronautics, astronomy, geodesy and navigation.

[0009] Ukrainian Utility Model No. 68352 (UA68352U) IPC G02B 023 / 00, published on March 26, 2012, discloses a small laser telescope in a receiver channel for determining the position of an artificial satellite. The telescope includes a collimator, a first focusing lens, an obstacle filter, a second focusing lens, a propeller shutter, and a photomultiplier device, all optically connected. A disk with four neutral density filters is located between the obstacle filter and the second focusing lens. The disk is connected to a disk rotation mechanism and a position sensor. The neutral density filters have a transmittance selected from 25%, 50%, 75%, and 100%.

[0010] RU2042155 IPC G01S 17 / 00 published on 08 / 08 / 1995 discloses a "Device for discovering object with stellar background", which provides for example for the discovery of artificial geosynchronous satellites. The device comprises a receiving telescope, a spatial light modulator equipped with a control unit, a coherent light source, a polarizing beam splitter, a lens, and a transmission television camera, the splitter, the lens, and the camera being optically connected. The device further comprises a comparison device, a threshold device, and a video monitoring device, the comparator, the threshold device, and the monitor being connected in series. The device further comprises a control and calculation unit. The device additionally comprises an electro-optical shutter, which is equipped with a control unit and is located between the coherent light source and the polarizing beam splitter. A spatial light modulator is an electro-optical transducer having, applied in series, a first transparent electrode, a dielectric mirror, a photorefractive crystal, and a second transparent electrode.

[0011] The above mentioned solutions do not solve the problem of ensuring operation of a device for capturing long exposure images in the presence of obstructions without interfering with the image capture process. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Russian Patent Invention No. 2662907 [Patent Document 2] Russian Patent Application Publication No. 93005699 [Patent Document 3] Ukrainian Utility Model No. 68352 [Patent Document 4] Russian Patent Invention No. 2042155 Summary of the Invention [Problem to be solved by the invention]

[0013] The technical result of the present invention therefore provides for operation of a device for capturing long exposure images in the presence of various obstructions without interfering with the image integration process. [Means for solving the problem]

[0014] In one embodiment, a device for capturing a long exposure image includes an image composition unit, an image capture unit, a primary shutter, and a secondary shutter connected to at least one obstruction detector via a control unit. The secondary shutter can be set between the image composition unit and the image capture unit. Furthermore, the secondary shutter can be set inside the image composition unit or integrated into the image composition unit.

[0015] A secondary shutter may also be provided in front of the image composition unit. The secondary shutter may be provided in the form of a high speed shutter. The obstruction detector may be provided in the form of a vibration detector. The obstruction detector may be provided in the form of a detector for monitoring objects that may distort the image.

[0016] The obstruction detector may also be provided in the form of a device for monitoring the satellite orbit.

[0017] In addition, a fault detector may be provided in the form of a detector that provides synchronization with the pulsed light source. The control unit may be configured to control the secondary shutter. The control unit may be configured to control both the primary and secondary shutters. The mentioned detector examples do not limit the embodiments of this device. There may be other faults whose occurrence requires the secondary shutter to be closed.

[0018] Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims, as well as the appended drawings.

[0019] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

[0020] The accompanying drawings, which are included to provide a further understanding of the invention, and which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a schematic diagram of a device for capturing long exposure images having a secondary shutter. [Diagram 2] FIG. 1 illustrates the operation of a secondary shutter mounted on a telescope. [Diagram 3] FIG. 13 is a schematic diagram of using an obstruction detector to control a secondary shutter, illustrated in an example telescope. [Figure 4] FIG. 2 is a schematic diagram of a device for capturing long exposure images, in which a control unit controls a primary shutter, a secondary shutter, and an image capture unit. [Diagram 5] FIG. 13 is a diagram showing operation times for a device with a secondary shutter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[0023] A device for capturing long exposure images (FIG. 1) comprises an image composing unit (1), e.g. a lens, an image capture unit (2), e.g. a detector, and a shutter (3), e.g. a primary shutter, providing the start and end of an integration mode in the image capture unit (2). The image capture unit (2) may be implemented based on a photosensitive array, in particular based on CCD matrix technology.

[0024] Typically, devices for capturing long exposure images use a primary shutter (3), implemented as an electronic, mechanical, electromechanical, or electro-optical shutter. Typically, primary shutters (3) are slow shutters (e.g. focal plane shutters) that can eliminate vibration shocks, electromagnetic radiation, heat, and other negative factors associated with high-speed devices in the operation of image capture units. Alternatively, they can be electronic shutters embedded in the device for capturing long exposure images, where the transition to a closed state not only blocks the input flow of electromagnetic energy to which the photosensitive array is exposed, but also disables the integration of that energy, even resulting in the loss of the integrated energy.

[0025] The device for capturing long exposure images according to the present invention also comprises a secondary shutter (4), which is connected to the obstruction detector (6) via the control unit (5). The secondary shutter (4) may be located anywhere upstream of the image capture unit (2). For example, the secondary shutter (4) may be located in front of the image composition unit (1) (i.e. the lens), or embedded in the image composition unit (1), or located behind the image composition unit (1). In particular, the secondary shutter (4) may be located at a distance from the image capture unit (2). Thereby, mechanical vibrations of the secondary shutter (4) as well as heat and electromagnetic energy emitted by the secondary shutter (4) do not have any significant negative effect on the image capture unit (2).

[0026] Devices for capturing long exposure images can be used in fields where it is necessary to capture electromagnetic radiation, especially in the optical radiation range of obscured objects, such as astronomy and microphotography (microscopy), especially fluorescence microscopy.

[0027] Figure 3 shows an example of a control unit (5) with a secondary shutter (4) and a disturbance detector (6) for the telescope (12). A diagram illustrating this implementation is provided in Figure 2. Sometimes disturbances to the capture of images by the camera attached to the telescope (12) are caused by light pulses from a satellite (14) captured in the frame, or from an outdoor pulsed lighting system (15), such as the system mentioned in Russian Patent No. 2662907 (RU2662907). Or seismic waves (13) generated by an earthquake disturb the telescope (12) and the image capture unit (2) (detector), thereby causing a shift in the projected image of the space object on the image capture unit of the telescope.

[0028] The secondary shutter (4) shall be a high-speed shutter, providing a rapid response to sudden and brief disturbances occurring, in order to reduce loss of exposure during switching, i.e. the secondary shutter (4) shall be capable of repeated switching between open and closed states within a few milliseconds or faster. The secondary shutter (4) may be provided as a mechanical or electromechanical device (focal plane shutter, lamellar shutter, rotary shutter, etc.), or as an electro-optical device (such as a liquid crystal-based optical touch panel), or as another suitable device.

[0029] A fault detector (8) for earthquake vibrations as well as other vibrations at the base of any device, such as a microscope, may be provided as a vibration detector. A wind load detector (11) may also be provided as a vibration detector.

[0030] The obstruction detector (9) for the light of a moving satellite may be provided as an object tracking detector, for example it may be provided as a device for investigating satellite orbits.

[0031] A fault detector (10) for light pollution by pulsed light sources may be provided as a detector for synchronizing with the pulsed light source.

[0032] The control unit (7), i.e. the unit for controlling the shutters and the image capture unit (FIG. 4), may be configured to control the primary shutter, the secondary shutter and the detector of the image capture unit, in which case the control unit (7) controls all switching on and off of the image capture unit (2).

[0033] The primary shutter (3) may be an electronic switch embedded in a photosensitive array, meaning that switching the array on and off simultaneously switches the primary shutter on and off.

[0034] A device for capturing long exposure images according to the diagram represented in FIG. 1 operates as follows.

[0035] Initially, the secondary shutter (4) is in an open state, which it keeps until a command comes from any of the fault detectors (8, 9, 10, 11).

[0036] Further, the photosensitive array of the image capture unit (2) is activated (FIGS. 2, 4, 5). The photosensitive array continues to activate when the image capture device is in operation, even when the device is exposed to an external disturbance. As mentioned, deactivation of the array will cause a loss of integrated light energy, and the process will start from the very beginning. Thus, the process of capturing an image begins by opening the primary shutter (3) for a time T (FIG. 5(A)). Usually, the primary shutter (3) is not a fast shutter in such devices. In case of a disturbance, the corresponding detector is triggered. It may be, for example, a seismic vibration detector (8) (FIG. 5(B)), a satellite tracking detector (9) (FIG. 5(C)), or an outdoor lighting system detector (10) (FIG. 5(D)). Activation of any of these detectors causes the closing of the secondary shutter (4) (FIG. 5(E)), thereby blocking the integration of a disturbed or misaligned image. The photosensitive array of the image capture unit (2) remains activated. The primary shutter (3) remains open. Furthermore, when the fault ends, the corresponding fault detector (unit 8, 9 or 10) sends a signal to the control unit (5) which generates a command to open the secondary shutter (4). The secondary shutter (4) is opened and resumes exposure until the next fault occurs, i.e. until the next close command comes from the control unit (5). The primary shutter (3) remains open until the end of the exposure, regardless of the occurrence of the fault.

[0037] FIG. 5(F) shows the long process of charge integration by the photosensitive array of the image capture unit (2) for a blurred object. Curve (16) shows the process of charge integration by the photosensitive array when the light of the photographed object is constant and the disturbances that occur are suppressed. Curve (17) shows the case without disturbances, so the integration is not interfered with. Comparison of curves (16) and (17) shows that when disturbances occur, the process of charge integration by the photosensitive array for a constant light of the photographed object requires more time.

[0038] The implementation of the device according to the diagram in Fig. 4 offers the possibility to compensate for the time lost for switching off the secondary shutter (4) in case of any fault occurring in order to guarantee the required exposure and to obtain an image of the desired quality. In this case, the fault detection unit (6) is connected to the control unit (7) of the image capture unit (2), which is also the shutter control unit. The fault detection unit (6) sends a signal to the control unit (7) which contains the interference time of the secondary shutter (4). In this way, the control unit (7) makes it possible to extend the exposure time of the image capture unit (2) and to compensate for the time lost while the secondary shutter (4) was closed.

[0039] To avoid degrading the capture quality of a particular frame, the exposure time is set to T comp = (T1+T2+T3+···), where T1, T2, and T3 are the time intervals when the secondary shutter (4) is closed in the event of a fault.

[0040] The control unit (7) according to the diagram shown in FIG. comp When implemented in this way, the control unit (7) is able to control the image capture unit (2).

[0041] In addition to the device vibration fault detector, a fault detector for inadvertently switched on lighting can be used, which is essentially a lighting synchronization detector. [Industrial Applicability]

[0042] The present invention may be implemented in a variety of commercially available devices as well as newly developed devices.

[0043] To that end, having described preferred embodiments, it will be apparent to those skilled in the art that certain advantages of the described method and apparatus are realized, and it will be understood that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the invention.

Claims

1. 1. A device for capturing long exposure images, comprising: an image composition unit; An image capture unit; A primary shutter; A secondary shutter; the secondary shutter is located in front of the image-composing unit; the secondary shutter is connected to at least one fault detector via a control unit; The device, wherein the control unit is configured to close the secondary shutter when at least one of the obstruction detectors detects an obstruction and to open the secondary shutter when the obstruction detector does not detect an obstruction when capturing an exposure image.

2. The device of claim 1 , wherein the secondary shutter is faster than the primary shutter.

3. The device of claim 1 comprising at least one said fault detector.

4. The device of claim 3 , wherein the fault detector is a vibration detector.

5. The device of claim 3 , wherein the fault detector is a pulsed light source detector.

6. The device of claim 3 , wherein the fault detector is a device for tracking satellites.

7. The device of claim 3 , wherein the obstruction detector is a device for monitoring objects that can distort an image due to optical obstructions occurring external to the device for capturing the long exposure image.

8. The device of claim 1 , wherein the control unit is configured to control both the primary shutter and the secondary shutter.

9. 1. A device for capturing long exposure images, comprising: an image composition unit; An image capture unit; A primary shutter; A secondary shutter; the secondary shutter is connected to at least one fault detector via a control unit; the control unit is configured to close the secondary shutter when the at least one obstruction detector detects an obstruction and to open the secondary shutter when the obstruction detector does not detect an obstruction during capture of the exposure image. The device, wherein the primary shutter remains independently open upon detecting the fault.

10. The device of claim 9 , wherein the secondary shutter is faster than the primary shutter.

11. The device of claim 9 comprising at least one said fault detector.

12. The device of claim 11 , wherein the fault detector is a vibration detector.

13. The device of claim 11 , wherein the fault detector is a pulsed light source detector.

14. The device of claim 11 , wherein the obstruction detector is a device for tracking satellites.

15. The device of claim 3 , wherein the obstruction detector is a device for monitoring objects that can distort an image due to optical obstructions occurring external to the device for capturing the long exposure image.

16. The device of claim 9 , wherein the control unit is configured to control both the primary shutter and the secondary shutter.

17. The device of claim 9 , wherein the secondary shutter is in front of the image-composing unit.

18. The device of claim 9 , wherein the secondary shutter is in front of the image capture unit.

19. The device of claim 9 , wherein the secondary shutter is integrated with the image-composing unit.

20. The device of claim 9 , wherein the primary shutter is integral with the image capture unit.

21. 1. A device for capturing long exposure images, comprising: an image composition unit; An image capture unit; A primary shutter; A secondary shutter; the secondary shutter is connected to at least one fault detector via a control unit; the control unit is configured to close the secondary shutter when the at least one obstruction detector detects an obstruction and to open the secondary shutter when the obstruction detector does not detect an obstruction during capture of the exposure image. The device, wherein the obstruction detector is either a vibration detector that detects shocks or vibrations of the ground or the device that obstruct exposure, or a pulsed light source synchronous detector that detects pulsed light from an illumination device that obstructs exposure.

22. The device of claim 21 , wherein the secondary shutter is faster than the primary shutter.

23. The device of claim 21 , wherein the control unit is configured to control both the primary shutter and the secondary shutter.

24. 1. A device for capturing long exposure images, comprising: an image composition unit; An image capture unit; A primary shutter; A secondary shutter; the secondary shutter is connected to at least one fault detector via a control unit; the control unit is configured to close the secondary shutter when at least one of the obstruction detectors detects an obstruction and to open the secondary shutter when the obstruction detector no longer detects an obstruction during capture of an exposure image; The control unit is configured to increase the exposure of the image capture unit using the primary shutter to compensate for missed exposure time because the secondary shutter was closed.

25. The device of claim 24 , wherein the secondary shutter is faster than the primary shutter.

26. 25. A device according to claim 24 comprising at least one said fault detector.

27. 27. The device of claim 26, wherein the fault detector is a vibration detector.

28. 27. The device of claim 26, wherein the fault detector is a pulsed light source detector.

29. 27. The device of claim 26, wherein the obstruction detector is a device for tracking satellites.

30. 27. The device of claim 26, wherein the obstruction detector is a device for monitoring objects that can distort an image due to optical obstructions occurring external to the device for capturing the long exposure image.

31. The device of claim 24 , wherein the control unit is configured to control both the primary shutter and the secondary shutter.

32. 1. A method for capturing a long exposure image, comprising: detecting a fault for capturing an image by the fault detector, and closing the secondary shutter upon occurrence of the fault by the control unit; The control unit opens the secondary shutter when there is no obstruction, A method in which the primary shutter remains open regardless of the obstruction.

33. 1. A method for capturing a long exposure image, comprising: Detecting an obstacle for capturing an image by an obstacle detector; The control unit closes the secondary shutter in the event of a fault. The control unit opens the secondary shutter when there is no obstruction, A method in which a control unit increases the exposure of the image capture unit using a primary shutter to compensate for time lost due to the secondary shutter being closed.

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