CN204813798U - Hand -held type fundus camera based on liquid lens - Google Patents

Abstract

The utility model relates to a hand -held type fundus camera based on liquid lens, which comprises a housin, inside source of illumination, image sensor, first lens subassembly, second lens subassembly, liquid lens, drive circuit, signal processing unit, control assembly and the power supply module of being equipped with of casing, signal processing unit for control source of illumination's operating condition still is used for receiving the data signal that the image processing sensor was gathered, with the definition evaluating indicator who acquires the image, and sends the operating condition that a control signal controlled drive circuit according to the definition evaluating indicator of image, drive circuit is used for receiving the operating condition of control signal in order to drive liquid lens that signal processing unit sent, power supply module for for source of illumination, image sensor, drive circuit, signal processing unit and control assembly power supply. The utility model discloses simple structure, small can realize full auto focus based on the feedback control of image definition index.

Description

Handheld Fundus Camera Based on Liquid Lens

technical field

The utility model relates to the field of medical imaging, in particular to a hand-held fundus camera based on a liquid lens.

Background technique

The hand-held fundus camera belongs to the field of medical imaging, and is used to obtain images of the retina of the human eye, to perform fundus disease inspection and to assist in the judgment of other organs. At present, there are mainly two methods for focusing the handheld fundus camera, one is manual focusing by adjusting the relative position of optical components or sensors, and the other is automatic focusing. However, the current manual focusing and automatic focusing methods require complex mechanical and motor drive methods, which limit the improvement of hand-held fundus cameras in terms of size, weight and battery life.

With the development of active optical devices, active optical technology is gradually applied to ophthalmic optical imaging, such as laser confocal technology. In the field of fundus cameras, some fundus cameras use deformable mirrors to eliminate the aberrations of the eyes and imaging optical systems to achieve cell-level imaging. The system requires a high-voltage amplifier to drive the deformable mirror. In addition, the optical path of this type of fundus microscope is very complicated, which cannot meet the portability and flexibility requirements of handheld devices.

Liquid lens is an inexpensive active optical device developed in recent years. It uses liquid as the optical channel and uses electromagnetic drive technology to change the optical power of the liquid lens to achieve the purpose of focusing. Since the liquid lens does not require an additional mechanical focusing mechanism and reduces the volume of the optical system, it has been applied in the endoscope. Among them, the Chinese invention patent with application number 201310728493.6 discloses a portable fundus camera based on a variable curvature liquid lens. The main purpose is to replace the traditional mechanical focusing structure with a liquid variable curvature lens to simplify the system structure. The invention adopts beam splitting to achieve the fundus illumination of guided light and white light, and introduces a beam splitter, crosshair and target locator in the imaging optical path to achieve the coincidence of visual axis and optical axis. The focusing method is manual adjustment. The control parameters of the liquid convex lens do not achieve autofocus. However, because the technical route of this invention introduces optical components such as two beam splitters, crosshairs and target locators, the optical path is more complicated, which increases the difficulty of camera installation and adjustment, and the reflected light from the fundus is very weak, so the beam splitter The introduction of the sensor further increases the requirements for the sensor and exposure, making it difficult to reduce the system cost, and the amount of light radiation borne by the human eye is also relatively large.

Utility model content

Aiming at the deficiencies of the prior art, the utility model aims to provide a hand-held fundus camera based on a liquid lens, which has a simple structure, a small volume, and can realize automatic focusing.

In order to achieve the above object, the utility model adopts the following technical solutions:

A hand-held fundus camera based on a liquid lens, comprising a casing, the casing is internally provided with an illumination light source, an image sensor, a first lens assembly, a second lens assembly, a liquid lens, a driving circuit, a signal processing unit, and a control assembly and power components;

The illumination light source is used for illuminating the fundus;

The image sensor is used to convert the optical signal of the acquired image into a digital signal;

The first lens assembly, located at the left front end of the housing, is used to focus the light beam emitted by the illumination source onto the fundus to form uniform illumination on the fundus, and is also used to gather the beam reflected back by the fundus;

The second lens assembly is located between the first lens assembly and the image sensor, and is used to focus the light beam reflected from the fundus onto the image sensor together with the first lens assembly;

The signal processing unit is used to control the working state of the lighting source, and is also used to receive and process the digital signal collected by the image sensor to obtain the image definition evaluation index, and send a control signal according to the image definition evaluation index to Control the working state of the drive circuit;

The driving circuit is used to receive the control signal sent by the signal processing unit to drive the working state of the liquid lens;

The control component is used to connect with the signal processing unit to realize the photographing control;

The power supply component is used to supply power to the lighting source, the image sensor, the drive circuit, the signal processing unit and the control component;

Wherein the liquid lens is located between the first lens assembly and the second lens assembly, or between the second lens assembly and the image sensor.

Preferably, the illumination light source includes at least one guiding light source and at least one exposure light source, and both the guiding light source and the exposure light source are connected to the signal processing unit.

Preferably, the first lens component is an aspherical lens.

Preferably, said second lens assembly consists of two separate doublet lenses.

Preferably, the control component is any one of a mechanical button or a touch screen connected to the signal processing unit.

Preferably, the handheld fundus camera further includes a display module, a data storage unit and a data transmission interface; the display module, the data storage unit and the data transmission interface are all connected to the signal processing unit and powered by a power supply component.

Preferably, the display module is located outside the housing, and the data storage unit and the data transmission interface are embedded in the housing.

Preferably, the data transmission interface is one of a wired data interface and a wireless data interface.

The beneficial effects of the utility model are as follows:

The liquid lens-based hand-held fundus camera has a simple structure and a small volume, and can realize automatic focusing based on the feedback control of the image definition index. The optical path in the utility model is relatively simple, which reduces the difficulty of camera installation and adjustment, so that the amount of light radiation borne by the human eye is relatively small, and the light beam reflected back by the fundus is relatively strong. And while ensuring the shooting quality, it also reduces the production cost of the hand-held fundus camera based on the liquid lens.

Description of drawings

FIG. 1 is a structural diagram of a preferred embodiment of the liquid lens-based handheld fundus camera of the present invention.

Fig. 2 is the illumination light path of a preferred embodiment of the liquid lens-based hand-held fundus camera of the present invention.

Fig. 3 is the imaging optical path of a preferred embodiment of the liquid lens-based handheld fundus camera of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, the utility model is further described:

Please refer to Fig. 1, the utility model relates to a hand-held fundus camera based on a liquid lens, and its preferred embodiment includes a housing 12, the housing 12 is internally provided with an illumination source 1, an image sensor 2, a first lens assembly 3, The second lens assembly 4 , the liquid lens 10 , the drive circuit 11 , the signal processing unit 5 , the control assembly 6 and the power supply assembly 13 .

Specifically, the illumination light source 1 is used for illuminating the fundus. Here, the illumination light source is a light source capable of emitting monochromatic or wide-band light beams with a wavelength between 400nm and 2000nm. The illumination light source can be one of light emitting diodes, lasers and flash lamps, or a combination of more than one of the above light sources. Preferably, the illumination light source 1 includes at least one guiding light source and at least one exposure light source, and both the guiding light source and the exposure light source are connected to the signal processing unit. The guiding light source can be turned off and on under the control of the signal processing unit. The exposure light source can be exposed under the control of the signal processing unit, wherein the exposure time is generally between 0.2 milliseconds and 300 milliseconds. Further preferably, the illuminating light source 1 may include an infrared LED (850nm band) and a white LED (450nm-650nm), both the infrared LED and the white LED may be embedded on the same PCB, wherein the infrared LED may be used as a guiding light source, White LEDs can be used as the exposure light source.

The image sensor 2 is used to convert the optical signal of the acquired image into a digital signal. The image sensor here is a two-dimensional image sensor, which may be one of CCD, CMOS or two-dimensional photoelectric sensing devices composed of one-dimensional sensing arrays. Preferably, the image sensor may be a CMOS chip with a resolution of 1920*1080.

As shown in Fig. 2 and Fig. 3, the first lens assembly 3 is located at the left front end of the housing, and is used to focus the light beam emitted by the illumination source onto the fundus to form uniform illumination on the fundus, that is, to form an illumination optical path. The first lens assembly is also used to gather the light beams reflected by the fundus to form an imaging optical path. Wherein, the first lens assembly is composed of a group of optical elements or spatial distances, and preferably, it may specifically be an aspherical lens.

The second lens assembly 4 , located between the first lens assembly 3 and the image sensor 2 , is used to focus the light beam reflected back from the fundus onto the image sensor 2 together with the first lens assembly 3 . The second lens assembly here is composed of a set of optical elements or spatial distances, each set of optical elements includes at least one lens. Wherein, preferably, the second lens assembly may be composed of two separated doublet lenses. The doublet lens here also plays a role in correcting chromatic aberration.

The signal processing unit 5 is used to control the working state of the lighting source, and is also used to receive and process the digital signal collected by the image sensor to obtain the image definition evaluation index, and send a control signal according to the image definition evaluation index to control The working state of the drive circuit 11. The signal processing unit 5 here may be a SOC including DSP and ARM chips. The control signal can control the strength of the signal loaded by the drive circuit 11 to the liquid lens 10 . In order to obtain the above control signal, the signal processing unit includes a liquid lens control algorithm module. The liquid lens control algorithm module calculates and loads according to the image definition evaluation index to obtain the signal strength of the liquid lens controller, that is, the control signal acting on the drive circuit.

Among them, the image clarity evaluation index is the transformation of the gray value of the fundus image. Generally, the sum of gray values in an area or several areas of the image is selected, or the sum of squares, or the sum of several times, or based on gray Value gradient, image entropy, value based on frequency-domain Fourier transform or wavelet transform.

The liquid lens control algorithm module adopts a feedback control algorithm based on image definition evaluation index, which can be PID, genetic algorithm, stochastic parallel gradient descent algorithm, simulated annealing algorithm or look-up table method. Preferably, the liquid lens control algorithm module adopts a hill-climbing method, which is a random feedback control algorithm. Because it is difficult to obtain an analytical expression between the image definition evaluation index and the control signal of the liquid lens, in this case, the random feedback control algorithm is generally used to maximize the image definition index, so that the highest image definition can be obtained.

The driving circuit 11 is used to receive the control signal sent by the signal processing unit to drive the working state of the liquid lens 10 . Wherein, the drive circuit is connected with the signal processing unit through the I2C interface, and is used to receive the control signal of the signal processing unit, and load the control signal to the liquid lens after conversion, so as to complete the control of the focal length of the liquid lens. The liquid lens 10 is located between the first lens assembly and the second lens assembly, or between the second lens assembly and the image sensor.

The control component 6 is used to connect with the signal processing unit 5 to realize the photographing control. As an input device, the control component can be any one of a mechanical button or a touch screen connected to the signal processing unit.

Furthermore, the power supply component 13 is used for supplying power to the illumination light source, the image sensor, the driving circuit, the signal processing unit and the control component. The power supply component can be a lithium battery, and of course can also be other types of batteries.

As further preferably, the hand-held fundus camera also includes a display module 7, a data storage unit 8 and a data transmission interface 9; the display module 7, the data storage unit 8 and the data transmission interface 9 are all connected to the signal processing unit, and are controlled by The power pack supplies power. The display module is located outside the casing, and the data storage unit and the data transmission interface are embedded in the casing.

Wherein, the control component 6 can control the working state of the display module 7 through the signal processing unit 5, that is, to realize browsing of pictures. The data storage unit 8 can be a mechanical hard disk, a solid state disk, or a memory card such as SD or T-Flash. The data transmission interface 9 is one of a wired data interface and a wireless data interface. When the data transmission interface 9 is a wired data interface, it may be a USB interface or a CameraLink interface. When the data transmission interface 9 is a wireless data interface, it can be any one of a Wifi interface, a Zigbee interface and a Bluetooth interface.

Specifically, the illumination optical path and imaging optical path of the hand-held fundus camera based on the liquid lens of the present invention are shown in Fig. 2 and Fig. 3 respectively. The light emitted by the illumination source enters the human eye through the first lens assembly to form an illumination light path. At the same time, the light beam reflected by the fundus is focused on the image sensor through the first lens assembly, the second lens assembly and the liquid lens in sequence, and the image sensor converts the optical signal of the acquired image into a digital signal and sends it to the signal processing unit to obtain the image The definition evaluation index, and send a control signal according to the image definition evaluation index, and the control signal is used to control the driving circuit to make the liquid lens automatically focus, so as to obtain a picture with higher definition.

For those skilled in the art, various other corresponding changes and modifications can be made according to the technical solutions and ideas described above, and all these changes and modifications should fall within the protection scope of the claims of the present invention .

Claims (8)

1. A hand-held fundus camera based on a liquid lens, comprising a housing, characterized in that, the housing is internally provided with an illumination light source, an image sensor, a first lens assembly, a second lens assembly, a liquid lens, a driving circuit, Signal processing unit, control components and power supply components; The illumination light source is used for illuminating the fundus; The image sensor is used to convert the optical signal of the acquired image into a digital signal; The first lens assembly, located at the left front end of the housing, is used to focus the light beam emitted by the illumination source onto the fundus to form uniform illumination on the fundus, and is also used to gather the beam reflected back by the fundus; The second lens assembly is located between the first lens assembly and the image sensor, and is used to focus the light beam reflected from the fundus onto the image sensor together with the first lens assembly; The signal processing unit is used to control the working state of the lighting source, and is also used to receive and process the digital signal collected by the image sensor to obtain the image definition evaluation index, and send a control signal according to the image definition evaluation index to Control the working state of the drive circuit; The driving circuit is used to receive the control signal sent by the signal processing unit to drive the working state of the liquid lens; The control component is used to connect with the signal processing unit to realize the photographing control; The power supply component is used to supply power to the lighting source, the image sensor, the drive circuit, the signal processing unit and the control component; Wherein the liquid lens is located between the first lens assembly and the second lens assembly, or between the second lens assembly and the image sensor. 2. The hand-held fundus camera based on a liquid lens as claimed in claim 1, wherein the illumination light source includes at least one guiding light source and at least one exposure light source, and the guiding light source and the exposure light source are both connected to the signal processing unit . 3. The liquid lens-based hand-held fundus camera of claim 1, wherein the first lens component is an aspherical lens. 4. The liquid lens based hand-held fundus camera of claim 1, wherein the second lens assembly consists of two separate doublet lenses. 5. The liquid lens-based hand-held fundus camera according to claim 1, wherein the control component is any one of a mechanical button or a touch screen connected to the signal processing unit. 6. The hand-held fundus camera based on liquid lens according to any one of claims 1 to 5, characterized in that: the hand-held fundus camera also includes a display module, a data storage unit and a data transmission interface; the display The module, the data storage unit and the data transmission interface are all connected with the signal processing unit and powered by the power supply component. 7. The liquid lens-based hand-held fundus camera according to claim 6, wherein the display module is located outside the casing, and the data storage unit and the data transmission interface are all embedded in the casing the interior of the body. 8. The liquid lens-based hand-held fundus camera according to claim 6, wherein the data transmission interface is one of a wired data interface and a wireless data interface.