Patent Publication Number: US-9427155-B2

Title: Optical apparatus and operating method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims benefit of U.S. Provisional Application Ser. No. 61/718,176, filed on Oct. 24, 2012, which is incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to optical apparatus, especially to an optical apparatus and an optical apparatus operating method used for providing information of intraocular pressure (IOP), cornea properties (e.g., elasticity, viscosity), and eye weight. 
     2. Description of the Prior Art 
     Due to its characteristics of non-invasion and fast response, the optical apparatus is widely used for non-contact measurement or inspection, especially in medical applications. For example, a published application (TW 101106376) shows a technology using optical interference to measure material properties of the sample. 
     Please refer to  FIG. 1 .  FIG. 1  illustrates a schematic diagram of a conventional non-contact tonometer disclosed in a prior art. As shown in  FIG. 1 , the non-contact tonometer  1  at least includes an air-puff unit AP, an optical emitting unit EU, and an optical receiving unit RU. The air-puff unit AP is used to generate an air pressure G to a sample SA (e.g., an eyeball). The optical emitting unit EU is used to emit an incident light L 1  to the sample SA. The optical receiving unit RU is used to receive the reflected light L 2  reflected by the sample SA. When the air pressure G reaches a surface of the cornea CA of the eyeball, the deformation of the cornea CA caused by the air pressure G will be detected by the optical receiving unit RU. The relationship between the applied force (evaluated from the air pressure G) and the deformation of the corneal CA will provide sufficient information for calculating an intraocular pressure of the eyeball. However, the conventional non-contact tonometer  1  fails to acquire other reference data about the cornea CA, such as the elasticity, viscosity, and central corneal thickness (CCT) of the cornea CA . . . etc, at the same time. 
     Therefore, the invention provides an optical apparatus and an optical apparatus operating method to solve the above-mentioned problems occurred in the prior arts. 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention is an optical apparatus used for non-contact inspection and measurement of a cornea of an eye. In this embodiment, the optical apparatus includes an optical measurement module, a central processing module, and an air-puff module. The air-puff module is used for generating an air pressure to a surface of the cornea according a blow pattern to cause a deformation of the cornea. The optical measurement module includes a first unit and a second unit. The first unit is used for measuring an intraocular pressure (IOP) of the eye according to the deformation of the cornea. The second unit is used for measuring properties of the cornea in an optical interference way. The central processing module is coupled to the first unit and the second unit and used for receiving and processing the intraocular pressure and the properties of the cornea to provide a result. 
     In an embodiment, the properties of the cornea include an elasticity of the cornea, a viscosity of the cornea, a central corneal thickness (CCT) of the cornea, a profile of the cornea, and a curvature of the cornea. 
     In an embodiment, the optical apparatus further includes a target confirming module used for confirming that the cornea of the eye is the target of the optical apparatus at first. 
     In an embodiment, the second unit includes an optical source, a coupling unit, and a reference reflector, the optical source emits an incident light to the coupling unit, and the coupling unit divides the incident light into a reference incident light emitted to the reference reflector and a sample incident light emitted to the cornea of the eye respectively, when the cornea is not deformed by the air pressure generated by the air-puff module, the coupling unit receives a reference reflected light reflected by the reference reflector and a first sample reflected light reflected by the un-deformed cornea respectively and generates a first optical interference result, the central processing module generates a corneal tomography image of the cornea according to the first optical interference result and obtains a central corneal thickness (CCT) of the cornea, a profile of the cornea, and a curvature of the cornea according to the corneal tomography image of the cornea; after the cornea is deformed by the air pressure generated by the air-puff module, the coupling unit receives the reference reflected light reflected by the reference reflector and a second sample reflected light reflected by the deformed cornea respectively and generates a second optical interference result, and the central processing module compares the first optical interference result with the second optical interference result to evaluate an elasticity of the cornea, a viscosity of the cornea, and a weight of the eye. 
     In an embodiment, the blow pattern includes duration of the air pressure, a magnitude of the air pressure, and a frequency of the air pressure. 
     In an embodiment, the first unit includes an optical emitter and an optical receiver; before the cornea is deformed, the optical emitter emits a first sensing light to the surface of the un-deformed cornea and the optical receiver receives a first reflected light reflected by the un-deformed cornea; after the cornea is deformed, the optical emitter emits a second sensing light to the surface of the deformed cornea and the optical receiver receives a second reflected light reflected by the deformed cornea, the central processing module obtains a signal variation between the first reflected light and the second reflected light and links the signal variation with the blow pattern to evaluate the intraocular pressure (IOP) of the eye. 
     Another embodiment of the invention is a method of operating an optical apparatus for non-contact inspection and measurement of a cornea of an eye. In this embodiment, the optical apparatus includes an air-puff module, an optical measurement module, and a central processing module. The optical measurement module includes a first unit and a second unit. The method includes steps of: (a) the second unit measuring properties of the cornea in an optical interference way; (b) the air-puff module generating an air pressure to a surface of the cornea according a blow pattern to cause a deformation of the cornea; (c) the first unit measuring an intraocular pressure (IOP) of the eye according to the deformation of the cornea; and (d) the central processing module receiving and processing the intraocular pressure and the properties of the cornea to provide a result. 
     Compared to the prior art, the optical apparatus and the optical apparatus operating method of the invention can provide more functions than a conventional non-contact tonometer to provide information of the intraocular pressure (IOP), the cornea properties (elasticity, viscosity, CCT), and eye weight at the same time. 
     The advantage and spirit of the invention may be understood by the following detailed descriptions together with the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE APPENDED DRAWINGS 
         FIG. 1  illustrates a schematic diagram of a conventional non-contact tonometer disclosed in a prior art. 
         FIG. 2  illustrates a function block diagram of the optical apparatus in an embodiment. 
         FIG. 3  illustrates a schematic diagram of the optical apparatus in another embodiment. 
         FIG. 4A  illustrates a cross-sectional diagram of the cornea having measured points at different positions. 
         FIG. 4B  illustrates a front-view of the cornea having measured points at different positions. 
         FIG. 5  illustrates a flow chart of the optical apparatus operating method in another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the invention is an optical apparatus used for non-contact inspection and measurement of a cornea of an eye. Please refer to  FIG. 2 .  FIG. 2  illustrates a function block diagram of the optical apparatus in this embodiment. 
     As shown in  FIG. 2 , the optical apparatus  2  includes an optical measurement module  20 , a central processing module  22 , an air-puff module  24 , and a target confirming module  26 . The optical measurement module  20  includes a first unit  20 A and a second unit  20 B. The central processing module  22  is coupled to the first unit  20 A and the second unit  20 B. It should be noticed that if ignoring the massive calculation and cost, the first unit  20 A can be replaced by the second unit  20 B. 
     In this embodiment, the target confirming module  26  is used for confirming that the sample SA (e.g., the cornea of the eye) is the target of the optical apparatus  2  at first. Then, the air-puff module  24  is used for generating an air pressure G to the sample SA according a blow pattern to cause a deformation of the sample SA. In fact, the blow pattern can include duration of the air pressure G, a magnitude of the air pressure G, and a frequency of the air pressure G, but not limited to this. For example, if the air-puff module  24  generates the air pressure G according to the blow pattern to a surface of a cornea of an eyeball, it will cause a deformation of the cornea. 
     The first unit  20 A is used for measuring an intraocular pressure (IOP) of the eye according to the deformation of the cornea. The second unit  20 B is used for measuring properties of the cornea in an optical interference way. 
     It should be noticed that the optical apparatus  2  has great flexibility in use. For example, the air-puff module  24  can be not only cooperated with the first unit  20 A and the second unit  20 B for measurement, but also cooperated with the first unit  20 A or the second unit  20 B alone for measurement depended on practical needs without any limitations. Besides, the optical measurement module  20  can only use the second unit  20 B alone for measuring cornea properties, but not limited to this. 
     In fact, the properties of the cornea include an elasticity of the cornea, a viscosity of the cornea, a central corneal thickness (CCT) of the cornea, a profile of the cornea, and a curvature of the cornea. The central processing module  22  is used for receiving and processing the intraocular pressure from the first unit  20 A and the properties of the cornea from the second unit  20 B respectively to provide a result. 
     Please refer to  FIG. 3 .  FIG. 3  illustrates a schematic diagram of the optical apparatus in another embodiment. As shown in  FIG. 3 , the optical apparatus  3  includes an optical measurement module, a central processing module  32 , and an air-puff module  34 . The optical measurement module includes a first unit  30 A and a second unit  30 B. 
     In this embodiment, the first unit  30 A includes an optical emitter EU and an optical receiver RU. Before the cornea CA is deformed by the air pressure G generated from the air-puff module  34  according to a blow pattern, the optical emitter EU emits a first sensing light to the surface of the un-deformed cornea CA and the optical receiver RU receives a first reflected light reflected by the un-deformed cornea CA. After the cornea CA is deformed, the optical emitter EU emits a second sensing light to the surface of the deformed cornea CA and the optical receiver RU receives a second reflected light reflected by the deformed cornea CA. The central processing module  32  is coupled to the optical receiver RU and obtains a signal variation between the first reflected light and the second reflected light and links the signal variation with the used blow pattern to evaluate the intraocular pressure (IOP) of the eye. 
     The second unit  30 B includes an optical source  300 , a coupling unit  302 , and a reference reflector  304 . The optical source  300  emits an incident light Lin to the coupling unit  302 , and the coupling unit  302  will divide the incident light Lin into a reference incident light Lin 1  emitted to the reference reflector  304  and a sample incident light Lin 2  emitted to the surface of the cornea CA respectively. After the reference incident light Lin 1  and the sample incident light Lin 2  are emitted to the reference reflector  304  and the surface of the cornea CA respectively, the reference reflector  304  and the surface of the cornea CA will reflect the reference incident light Lin 1  and the sample incident light Lin 2  respectively. 
     When the cornea CA is not deformed by the air pressure G generated from the air-puff module  34  according to the blow pattern, the coupling unit  302  will receive a reference reflected light reflected by the reference reflector  304  and a first sample reflected light reflected by the surface of the un-deformed cornea CA respectively and generate a first optical interference result. Afterward, the central processing module  32  will generate a corneal tomography image of the un-deformed cornea CA according to the first optical interference result and obtain a central corneal thickness (CCT) of the cornea CA, a profile of the cornea CA, and a curvature of the cornea CA according to the corneal tomography image of the un-deformed cornea CA. 
     After the cornea CA is deformed by the air pressure G generated from the air-puff module  34  according to the blow pattern, the coupling unit  302  will receive the reference reflected light reflected by the reference reflector  304  and a second sample reflected light reflected by the deformed cornea CA respectively and generate a second optical interference result. Then, the central processing module  32  will compare the first optical interference result with the second optical interference result to evaluate an elasticity and a viscosity of the cornea CA, and a weight of the eye. 
     In fact, if the reference reflector  304  is fixed, the reference reflected light reflected by the reference reflector  304  will be also unchanged. Since the coupling unit  302  will receive the first sample reflected light reflected by the surface of the un-deformed cornea CA and the second sample reflected light reflected by the deformed cornea CA, the central processing module  32  can also compare the first sample reflected light and the second sample reflected light to evaluate the deformation of the cornea CA, but not limited to this. 
     In this embodiment, the properties of the cornea CA such as elasticity, viscosity or weight are derived from force-motion relationship. Please refer to the equations shown below for motion-force relationship.
 
 F=kx   (Equation 1)
 
     In Equation 1, k represents a spring constant, and once force and displacement are confirmed, then k can be evaluated. More properties can be added for Equation 2 for more complex system (more closing real system) such as:
 
 F=kx+cx′+mx″   (Equation 2)
 
     Wherein c represents a damping factor and m represents mass respectively. And Equation 2 can be explored to a matrix for cornea properties measurement by different applied force at different points, as shown in Equations 3a˜3c:
 
 F   1   =kx   1   +cx   1   ′+mx   1 ″  (Equation 3a)
 
 F   2   =kx   2   +cx   2   ′+mx   2 ″  (Equation 3b)
 
 F   3   =kx   3   +cx   3   ′+mx   3 ″  (Equation 3c)
 
     Equation 3a˜3c can be also shown in a matrix form: 
     
       
         
           
             
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     Since the cornea tomography is established by optical interference, in practical applications, the measured points of cornea CA can be widely chosen at different positions of the cornea CA, no matter at the surface of the cornea CA or inside the cornea CA, as the measured points P 1 ˜P 5  shown in  FIG. 4A  and the measured points P 6 ˜P 10  shown in  FIG. 4B . 
     The displacement x, velocity x′, and acceleration x″ all can be acquired from a predict distance which reference end set by different locations (concept just same as recording time duration while deformed one point to another point). Of course the frequency domain optical coherence tomography skill can be implemented here if fast speed is first priority. 
     Another embodiment of the invention is a method of operating an optical apparatus for non-contact inspection and measurement of a cornea of an eye. In this embodiment, the optical apparatus includes an air-puff module, an optical measurement module, a central processing module, and a target confirming module. The optical measurement module includes a first unit and a second unit. It should be noticed that the optical apparatus has great flexibility in use. For example, the air-puff module can be not only cooperated with the first unit and the second unit for measurement, but also cooperated with the first unit or the second unit alone for measurement depended on practical needs without any limitations. Besides, the optical measurement module can only use the second unit alone for measuring cornea properties, but not limited to this. 
     Please refer to  FIG. 5 .  FIG. 5  illustrates a flow chart of the optical apparatus operating method in this embodiment. As shown in  FIG. 5 , in the step S 10 , the target confirming module confirms that the cornea of the eye is the target of the optical apparatus at first. In the step S 12 , the second unit measures properties of the cornea in an optical interference way. In the step S 14 , the air-puff module generates an air pressure to a surface of the cornea according a blow pattern to cause a deformation of the cornea. In the step S 16 , the first unit measures an intraocular pressure (IOP) of the eye according to the deformation of the cornea. In the step S 18 , the central processing module receives and processes the intraocular pressure and the properties of the cornea to provide a result. 
     Compared to the prior art, the optical apparatus and the optical apparatus operating method of the invention can provide more functions than a conventional non-contact tonometer to provide information of the intraocular pressure (IOP), the cornea properties (elasticity, viscosity, CCT), and eye weight at the same time. 
     With the example and explanations above, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.