RU2604110C2 - Monitoring and recording device with locally-adaptive optical protection - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: invention relates to devices for viewing real-time scenes with protection of optical sensor of device and/or vision of a viewer from unnecessarily bright light. Device has series-arranged on one optical axis optical sensor, spatial light modulator and display unit, as well as a processor module, data output of which is electronic output of the device for a signal of brightness normalized image of external spatially distributed light source which is optically connected to the input of the display unit.

EFFECT: wider dynamic range of optical protection, improved accuracy of local adaptation of optical protection.

1 cl, 3 dwg

Description

Technical field

The invention relates to devices for observing real scenes with the protection of the optical sensor of the device and / or the observer’s vision from excessively bright light, more precisely, to observational recording devices with locally adaptive light protection filters for attenuating interfering light from intense optical sources while maintaining normal visual perception of the remaining objects observed scenes, and can be used to create various observational-recording devices for vision, as well as for photo, video cameras, ra working in bright sunlight, including when direct sunlight falls on the input of the device and the direct visibility of the solar disk in the observed scene.

State of the art

Known observational device with integrated adaptive optical protection [1], containing a grayscale spatial light modulator with uniform optical transmission throughout the aperture and an optical sensor, the input of which is optically connected to part of the aperture of the spatial light modulator, as well as a processor module, the input of which is connected to an electronic the output of the optical sensor, the output of the processor module is connected to the electronic input of the grayscale spatial light modulator, the optical input of which is an input device I connected to the outside spatially nonuniform light source and output device is an optical output grayscale spatial light modulator.

This known device provides optical protection for the observer’s vision (eyes) when perceiving an external spatially inhomogeneous light source (spatial distribution of light brightness over objects of the observed scene) through an aperture of a half-tone spatial light modulator. A disadvantage of the known device is the inability to simultaneously provide effective vision protection from local areas of excessively bright light in the observed scene and to maintain a clear visual perception of the remaining objects of the observed scene having low and medium brightness. Indeed, the implementation of such a low optical transmittance over the entire aperture of the spatial light modulator, which corresponds to sufficient suppression of interfering light from the brightest local source (for example, from the light of the solar disk), leads to poor visibility of all objects in the scene with low and medium brightness when observed through aperture with such low optical transmittance.

The closest in technical essence to the claimed device is an observational recording device with a locally adaptive optical protection [2], containing a binary spatial light modulator (BPSM) sequentially located on the same optical axis with the number MN of optical shutter elements (each with two optical transmittance values) ) and an optical sensor with a single photosensitive element, where M and N are the number of rows and columns of the BPMS address matrix, as well as the processor module and the grayscale is simple a spatial light modulator (PPMS) with the number MN of light-modulating elements (each with a “gray scale” of optical transmission), the optical input of which is connected to an external spatially distributed light source, while the electronic input of the PPMS is connected to the control output of the processor module, the input of which is connected to the electronic output of the optical sensor, and the scanning output of the processor module is connected to the electronic input of the BPMS, and the MNs of the first intersect in the aperture of the photosensitive element of the optical sensor arctic optical axes passing through the corresponding MN optical gate elements of the BPSM, and the optical output of the BMSC is the output of the device for a spatially distributed light source normalized to the brightness of the image, while MN of the second partial optical axes passing through the MN of light modulating intersect at the observation point of the output of the device PPMS elements.

In the known device at the beginning of the adaptation cycle due to the alternate opening (transition to a state with maximum optical transmission) MN optical gate elements BPMS (due to the supply to its electronic input of a signal from the scanning output of the processor module) light fluxes from the corresponding MN local areas of the external spatially distributed The light source sequentially falls on a single photosensitive element of the optical sensor. As a result, a temporary element-wise scan of an image of an external spatially distributed light source is generated at its electronic output, which is fed to the input of the processor module, at the control output of which an optical transmission control signal PPMS is generated. The spatial distribution of optical transmission is realized in the PPMS aperture, which suppresses excessively bright light in the normalized image of an external spatially distributed light source, which is formed on the retina of the observer’s eye located at the exit point of the device and which receives light through the PPMS aperture from an external spatially distributed source Sveta. The brightness normalization is ensured by the fact that the brightest local areas of the latter (corresponding to interfering light) are viewed through the darkest local areas of the aperture of the additional spatial light modulator, which provides local optical vision protection at the end of the adaptation cycle.

The first disadvantage of the known device is the limited dynamic range of the optical sensor compared to the dynamic range of light brightness in real-world scenes, which reaches a brightness of 10 ⁵ ÷ 10 ⁶ lux in direct sunlight of objects of real scenes and in direct observation of the solar disk, which is much higher than the upper dynamic range limit of standard optical sensors. Since the optical sensor directly (without attenuation) receives light from each local area of the external spatially distributed light source, the dynamic range of the known device does not exceed the dynamic range of the optical sensor.

The second disadvantage of the known device is insufficiently accurate local adaptation. The exact suppression of interfering light from various local regions of an external spatially distributed light source by the action of the corresponding local regions of optical attenuation (optical density) in the PPMS aperture is problematic when the spatially distributed light source moves in physical space along the transverse (relative to the optical axis of the device) coordinates. Indeed, the MN of the first partial optical axes (making up the angular field of view of the optical sensor) does not coincide in the average viewing angle with the MN of the second partial optical axes (making up the angular field of view of the observer). With the transverse movement of the observed optical interfering light source, this difference in the average viewing angles in the general case leads to the appearance of a spatial mismatch (depending on the specific location of the interfering light sources) between the position of the spatial distribution of optical attenuation in the aperture of the PMSC and the spatial distribution of brightness in an external spatially distributed source Sveta. As a result, the second disadvantage of the known device is the low accuracy of local adaptation of optical protection with a variable transverse position of the interfering light source (or when changing the direction of the optical axis of the device due to its angular displacement relative to the observed scene).

The objective of the invention is to expand the dynamic range and improve the accuracy of local adaptation of optical protection.

Disclosure of invention

The task in an observational-recording device with a locally adaptive optical protection containing a spatial light modulator (PMS) sequentially located on the same optical axis with the number MN of light-modulating elements and an optical sensor, as well as a processor module, where M and N are the number of lines and the number of columns of the PMS address matrix, while the input of the processor module is connected to the output of the optical sensor, the control output of the processor module is connected to the electronic input of the PMS, it is decided by o the optical sensor is made with the number MN of groups of light-receiving elements, a display unit is additionally introduced into the device, in the object space of which there is an external spatially distributed light source, and in the image space of the display unit there is a PMS aperture and a light-receiving surface of the optical sensor, the mnth light-modulating the PMS element adjoins the mnth group of light-sensing elements of the optical sensor, where m = 1, 2, ..., Μ; n = 1, 2, ..., Ν, while the processor unit is provided with an information output, which is the electronic output of the device for a scan signal of an external spatially distributed light source normalized by brightness to the image.

The task of expanding the dynamic range of optical protection is achieved by achieving the first technical result, which consists in compressing with the help of the PMS the dynamic range of the light flux incident on the light-reflecting surface of the optical sensor. Reducing the excessive brightness of the light flux to the normalized maximum level (not exceeding the dynamic range of the optical sensor) occurs when the light flux passes through the corresponding local regions of the ICP with reduced optical transmittance (inversely proportional to the values of the excessive brightness of the light in the corresponding local regions of the external spatially distributed light source) .

The task of improving the accuracy of local adaptation of optical protection when the transverse (relative to the axis of the device) position of the interfering light sources is solved by achieving the second technical result, which consists in automatically matching the spatial arrangement of the groups of light-sensing elements of the optical sensor with the corresponding local areas of optical transmission in the aperture of the ICP. Indeed, at the beginning of the adaptation cycle, the mnth light-modulating PMS element transmits the corresponding mnth partial light flux (with excessive brightness) to the corresponding mnth group of light-sensing elements of the optical sensor. During the adaptation cycle, the mnth light-modulating PMS element receives a control signal from the same mn-th group of photosensitive elements of the optical sensor through the processor module. At the end of the adaptation cycle, the control voltage reaches an amplitude that ensures the optical transmittance of the mnth light-modulating PMS element of such a value that reduces the brightness of the mnth partial light flux to a normalized value (not exceeding the dynamic range of the optical sensor). Moreover, the accuracy of the local adaptation does not depend on the transverse location of the external spatially distributed light source relative to the device, since when changing the transverse location of the external spatially distributed light source (or when changing the angular position of the optical axis of the device relative to the observed scene), the geometry of the optical scheme of local adaptation is not violated . Moving the image of a point source of interfering bright light along the light-reflecting surface of the optical sensor is accompanied by a synchronous (coordinated) change in the position of the light flux of the image of this source in the aperture of the spatial light modulator.

In a particular embodiment of the device, the optical sensor is made with a light-transmitting aperture, the optical output of which is the optical output of the device for direct visual observation of the image of an external spatially distributed light source in the aperture of the optical sensor.

Brief Description of the Drawings

The implementation of the invention is illustrated by drawings, in the drawings of which are presented:

FIG. 1 is a general diagram of an observational recording device with locally adaptive optical protection.

FIG. 2 - the location of the object space, the image space, the main planes and the main focal lengths of the display unit.

FIG. 3 is a diagram of a particular embodiment of a device with an optical output.

The implementation of the invention

The device (Fig. 1) contains an optical sensor 1 with MN groups of light-sensing elements sequentially located on the same optical axis AA, a spatial light modulator (PMS) 2 with the number MN of light-modulating elements and a display unit 3, as well as a processor module 4, an external spatially distributed light source 5 (spatial brightness distribution in the observed external scene) is located in the object space of the display unit 3, an aperture is located in the image space of the display unit 3 2 and cheers ICP svetovosprinimayuschaya surface of the optical sensor 1, the mn-th ICP light modulating member 2 adjoins the mn-th group of optical sensor elements svetovosprinimayuschih 1, where m = 1, 2, ..., Μ; n = 1, 2, ..., Ν. The input of the processor module 4 is connected to the electronic output of the optical sensor 1, the control output of the processor module 4 is connected to the electronic input of the ICP 2, and the information output 4 _{1 of the} processor module 4 is the electronic output of the device for the scan signal of the brightness-normalized image of an external spatially distributed light source 5 . The electronic output of the device, for example, is connected to the input of the display module 6 with the optical output 7 of its screen.

The main planes D ₁ , D ₂ and the main focal lengths F of the display unit 3 are shown in FIG. 2 with the geometry of the ray path when constructing the image o _{mn of a} point object O _mn .

In a particular embodiment of the device (Fig. 3), the imaging unit 3 is made in the form of a spherical lens 3 ₁ , the optical sensor 1 is made with a translucent aperture, the output 1 _{1 of} which is the optical output of the device for a brightness-normalized image of a spatially distributed light source 5.

The device operates as follows. Using the display unit 3, the image of the mnth local region of the external spatially distributed light source 5 is formed on the mnth group of light-sensing elements of the optical sensor 1. In this case, the corresponding mnth partial luminous flux of the image passes through the mnth light-modulating element PMS 2, which at the beginning of the adaptation cycle is in a completely open state with the value T _mn = T _mn ^{(max) of} maximum optical transmittance regardless of the initial value J _mn ^{(init) of} the light intensity of the mnth partial light trade flow. For definiteness (without loss of generality), it is accepted that an increase in the intensity J _{mn of} the light incident on the mnth group of light-sensing elements of the optical sensor 1 causes a directly proportional increase in the electric voltage at the electronic output of the optical sensor 1, corresponding to the output electronic signal from the mnth groups of light-sensing elements of the optical sensor 1. In this case, an increase in the corresponding control electric voltage U _mn at the mnth light-modulating element PMS 2 causes the inversely proportional decrease in the optical transmittance (directly proportional to the increase in the optical attenuation χ _mn = 1 / T _mn ) for the intensity of the light passing through the mnth light-modulating element PMS 2. At the beginning of the adaptation cycle, mn falls on the mn-th group of light-receiving elements of the optical sensor 1 -th partial luminous flux of the image with greater intensity, the greater the brightness of the mn-th element of the external spatially distributed light source 5. The achievement of the threshold value J _mn ^(threshold) for the value J _mn ^{(init) of the} initial intensity of the mnth partial light flux incident on the light-reflecting surface of the optical sensor 1 leads to the value U _mn ^{(threshold) of the} control electric voltage U _mn at the electronic output of the optical sensor 1 in accordance with the ratios

ICP 2 is made with a threshold U _mn ^(threshold) for the value of the control voltage U _mn , satisfying the relation

according to which, when the control voltage U _mn is less than the threshold value U _mn ^(threshold) , the optical transmittance T _mn is equal to the maximum value T _mn ^(max) .

For values of the control voltage U _mn exceeding the threshold voltage U _mn ^(threshold) , the nature of the reduction in optical transmission T _{mn of the} ICP 2 depends on the type of its transfer characteristic T _mn {U _mn }. With the binary transfer characteristic of PMS 2, the value of T _mn ^(binary) has only two values (T _min and T _max ), therefore, at the end of the adaptation cycle, the value of T _mn changes stepwise to the minimum value of T _min , which corresponds to the complete attenuation of light with an intensity J _mn higher threshold value J _mn ^(threshold)

With a grayscale (with a “gray” scale) transfer characteristic of PMS 2, the value of T _mn ^(gray) decreases to

where J _top is the maximum maximum value of the light intensity on the optical sensor 1, corresponding to the upper limit of its dynamic range;

f is a normalization function that determines the nature of the reproduction of the normalized brightness of light in the output image.

On the screen of the display module 6, at the end of the adaptation cycle, a brightness-normalized image of an external spatially distributed light source 5 is reproduced, in which the light intensities from all MN local areas of the observed image are brought to values that are comfortable for seeing. Also, the normalized image signal from the output 4 ₁ can be transmitted via communication channels to a remote storage (recording) or display device.

The current spatial distribution of the optical transmittance in the aperture of the ICP 2 is replaced at the end of the next adaptation cycle with the corresponding distribution of optical density. Methods of mathematical prediction of the dynamics of changes in the distribution of light brightness can be used to preset the initial distribution of the optical transmittance of the PMS 2 in the next cycle.

The spatial resolution of the optical sensor 1 is preferably higher than the spatial frequency of the arrangement of the light-modulating elements of the ICP 2, since the function of the optical sensor is to produce an output image with a maximum resolution, and the function of the ICP 2 is to attenuate the light of optical sources, which usually have a size much more than a permission element. Therefore, it was established in the general case that one PMS element 2 corresponds to a group of light-sensing elements of the optical sensor 1 (which in the extreme case reduces to a single light-sensing element).

From the path of the rays in the scheme of the display unit 3 (Fig. 2), it is seen that the longitudinal (along the Z axis) changes in the position of the mnth local region (represented for simplicity by the point object O _mn ) of the external spatially distributed light source 5 cause longitudinal (along the axis z) moving the corresponding image o _mn . When the longitudinal displacements of the object O _mn fit into the depth of the sharply imaged space of the display unit 3, on the optical sensor 1, the corresponding image O _mn is sharp. Preservation of the image sharpness o _mn when the moving object O _mn leaves the depth limits of the sharply imaged space is provided, for example, by changing the value F of the main focal length of the display unit 3.

A feature of the operation of a particular embodiment of the device (Fig. 3) is that the normalized mnth partial light flux passes through a light-permeable aperture of the optical sensor 1, the output 1 _{1 of} which is the optical output of the device, on which the observer’s vision directly perceives the brightness-normalized image of the external spatially distributed light source 5.

The task of expanding the dynamic range of optical protection is achieved by achieving the first technical result, which consists in compressing the dynamic range of the input light (by changing the optical transmittance of the PMS 2), bringing its value to the dynamic range of the optical sensor. The expansion of the dynamic range of optical protection compared with the dynamic range of the optical sensor is determined by the maximum optical attenuation coefficient of the PMS 2.

The task of improving the accuracy of localization of optical protection is achieved by achieving the second technical result, namely, that the local areas of the “protective” distribution of the optical transmission of the PMS 2 with high accuracy coincide with the corresponding “protected” local areas of the optical sensor 1, regardless of the transverse spatial arrangement of the external spatial distributed light source 5 (while neglecting the thickness of the ICP 2). Indeed, the transverse (along the X, Y coordinates) movement of the local region of the external spatially distributed light source 5, for example, from the cell mn to the cell (m + 1) (n + 1) of the observed part of the physical space, leads to a transverse movement (along the x coordinates , y) images of this local region from the mnth group of light-receiving elements in the (m + 1) (n + 1) -th group of light-receiving elements of the optical sensor 1, accompanied by a proportional movement of the corresponding partial light flux of the image from mn- a light modulating element in the (m + 1) (n + 1) th light modulating element 2 ICP preserving their spatial coincidence.

Industrial applicability

The invention can be used to create observational devices and video, cameras with local optical protection for comfortable visual perception and shooting of real scenes in conditions of illumination of objects with direct sunlight, including the presence of a solar disk in the field of view.

A specific example of a spatial light modulator is an optical modulator on nematic [3] or ferroelectric [4] liquid crystals.

Specific examples of the implementation of an optical sensor are on charge-coupled devices (CCDs) or on complementary metal-oxide-semiconductor (CMOS) structures, including the implementation of an optical sensor with a translucent aperture in the form of a plastic panel with internal photoluminescence recorded by the peripheral lines of photodetectors [5 ].

Literature

1. Yang Y. Sunlight attenuation visor. - US Patent No. 8083385, pending. 10/26/2007, published. 12/27/2011.

2. Yezhov V.A. A method of light-protective filtering with zonal adaptation and a device for its implementation. - RF patent No. 2482526, declared. 10/13/2011, published. 05/20/2013.

3. Yang D.-K., Wu S.-T. Fundamentals of liquid crystal devices. - John Wiley & Sons, London, 2006.

4. Koppelhuber A., Bimber O. Towards a transparent, flexible, scalable and disposable image sensor using thin-film luminescent concentrators. - Optics Express, 2013, Vol. 21, No. 4, pp. 4796-4810.

Claims (2)

1. An observational recording device with locally adaptive optical protection, comprising a spatial light modulator and an optical sensor sequentially located on the same optical axis, as well as a processor module, while the spatial light modulator contains MN light-modulating elements, where M and N are the number of lines, respectively and the number of columns of the address matrix of the spatial light modulator, the input of the processor module is connected to the output of the optical sensor, the control output of the processor module is connected n to the electronic input of the spatial light modulator, characterized in that the optical sensor is made with MN groups of light-sensing elements, a display unit is additionally introduced into the device, in the object space of which there is an external spatially distributed light source, and in the image space there is an aperture of the spatial light modulator and an aperture of the optical sensor, and the mnth light-modulating element of the spatial light modulator is adjacent to the mnth group their elements of the optical sensor, where m = 1, 2, ..., M; n = 1, 2, ..., N, and the processor module is made with an information output, which is the electronic output of the device for the scan signal normalized by brightness of the image. 2. The device according to claim 1, characterized in that the optical sensor is made with a translucent aperture, the output of which is the optical output of the device for a normalized image brightness.

Images