JP4679945B2 - Optical property measuring device - Google Patents

Description

  The present invention relates to an improvement in an optical property measuring apparatus that measures optical properties of an eye.

2. Description of the Related Art Conventionally, as an optical characteristic measuring apparatus for measuring optical characteristics of an eye, an apparatus using a split optical member such as a Hartmann plate is known (for example, see Patent Document 1).
WO2003 / 022138

  However, this conventional optical characteristic measuring apparatus has a problem that the measurement range is narrow, and conventionally, the measurement range has been expanded by separately providing an optical system for rough measurement.

  However, if an optical system for rough measurement is separately provided, the structure of the entire apparatus becomes complicated accordingly, which causes a cost increase.

  The present invention has been made in view of the above circumstances, and without adopting a structure in which an optical system for coarse measurement is added exclusively to an optical system for accurately measuring optical characteristics, An object of the present invention is to provide an optical property measuring apparatus capable of measuring optical properties.

  According to a first aspect of the present invention, there is provided an optical characteristic measuring apparatus comprising: an irradiation optical system including a light source unit that irradiates a measured eye with a predetermined pattern of light; and a light beam for focusing reflected light from the eye to be measured. A focusing optical member for adjusting the state, a light receiving optical system including a light receiving unit that receives light through a splitting optical element that divides the light beam from the focusing optical member into a plurality of light beams, and measurement data from the light receiving unit. The optical characteristics of the eye to be measured are calculated by having a rough measurement mode for obtaining the refractive power of the eye to be measured based on the frequency component of the light receiving position of the received light signal and a precise measurement mode for obtaining the wavefront aberration from the interval between the light receiving positions. Obtained in the precision measurement mode performed by the computing unit after being controlled by the control unit, the control unit for adjusting and controlling the focusing optical member based on the refractive power obtained in the rough measurement mode Optical characteristics of eyes based on data And obtaining the.

  In the optical characteristic measuring apparatus according to claim 2 of the present invention, the irradiation optical system forms a substantially point light source as a predetermined pattern on the fundus of the eye to be measured, and the split optical member of the light receiving optical system It is composed of a Hartmann plate that divides the reflected light from the measurement eye into a plurality of light beams, the light reception signal from the light receiving unit corresponds to a Hartmann image, and the display unit is a refractive power distribution or power map of the eyeball of the eye to be measured Is characterized in that it is graphically displayed.

  The optical characteristic measuring apparatus according to claim 3 of the present invention is an optical characteristic measuring apparatus having a split optical member, an irradiation optical system including a light source unit that irradiates a light to be measured with a predetermined pattern, and the eye to be measured. A light receiving optical system including a light receiving unit that receives the reflected light from the light through a splitting optical element that divides the light into a plurality of light fluxes, and a light receiving signal that indicates measurement data from the light receiving unit based on a frequency component at the light receiving position. A calculation unit having a rough measurement mode for calculating the refractive power of the eye to be measured and calculating the optical characteristics of the eye to be measured; and an optical characteristic of the eye based on the refractive power obtained in the rough measurement mode.

  According to the present invention, it is possible to measure a wide range of optical characteristics of an eye without adopting a structure in which an optical system for coarse measurement is added to an optical system for precisely measuring optical characteristics, and the structure of the entire apparatus. Can be simplified and the cost can be reduced.

  Embodiments of an optical characteristic measuring apparatus according to the present invention will be described below with reference to the embodiments shown in the drawings.

  FIG. 1 shows an optical system of an optical characteristic measuring apparatus according to the present invention. In FIG. 1, 1 is an eye to be measured, 2 is an anterior ocular segment image observation optical system, and 3 is a measurement optical system.

  The anterior ocular segment image observation optical system 2 includes an anterior ocular segment illumination light source 4, a placido ring 4 ′, an objective lens 5, an illumination optical system 6 for adjusting the working distance, and a light receiving optical system for adjusting the working distance. 7, half mirror 8, half mirror 9d, fixation target projection optical system 9, iris diaphragm 10, relay lens 11, half mirror 14c, relay lens 13, alignment optical system 14, imaging lens 15, and CCD image sensor 16. It is configured.

  The ring-shaped illumination light source unit 4 illuminates the anterior segment of the eye 1 to be measured. The illumination optical system 6 is generally composed of an illumination LED 6a and a collimator lens 6b. The light receiving optical system 7 is roughly composed of a condenser lens 7a and a light receiving element 7b. The illumination optical system 6 illuminates the cornea C of the eye 1 to be measured, and the reflected light from the cornea C is received by the light receiving optical system 7, whereby the optical axis from the apex P ′ of the cornea C to the front surface of the objective lens 5. The working distance in the direction is adjusted.

  The fixation target projection optical system 9 is roughly composed of a fixation target light source 9a, a fixation target pattern 9b, a projection lens 9c, and a half mirror 9d. The fixation target pattern 9b is conjugate with the fundus F of the eye 1 to be measured, and an image of the fixation target pattern 9b is projected onto the fundus F of the eye 1 to be measured through the half mirror 9d, the half mirror 8, and the objective lens 5. Is to measure the optical properties of the eye while fixing the fixation target.

  The alignment optical system 14 is generally composed of an illumination light source 14a, a condenser lens 14b, and a half mirror 12. The illumination light from the illumination light source 14 a is collected by the condenser lens 14 b, reflected by the half mirror 14 c, and the cornea of the eye 1 to be measured through the relay lens 11, iris diaphragm 10, half mirror 9 d, half mirror 8, and objective lens 5. Projected onto C.

  The anterior segment image of the eye 1 to be measured is a CCD image pickup device 16 via the objective lens 5, half mirror 8, half mirror 9 d, iris diaphragm 10, relay lens 11, half mirror 14 c, relay lens 13, and imaging lens 15. Is imaged. The video signal from the CCD image pickup device 16 is input to an arithmetic unit described later and appropriately processed, and an anterior segment image FA is displayed on a screen G (see FIG. 2) of a display unit 34 described later. While observing the anterior eye part image FA with the naked eye, alignment adjustment and working distance adjustment in the vertical and horizontal directions of the apparatus main body with respect to the eye 1 to be measured are performed.

  The measurement optical system 3 is generally composed of a rotating prism 17, a half mirror 18, a relay lens 19, an iris diaphragm 20, a relay lens 21, a relay lens 22, a reflection mirror 23, a relay lens 24, and a measurement unit 25. .

  The measurement unit 25 is mainly composed of a measurement light projection light source 26 and a measurement light receiving optical system 27. The measurement light projection light source 26, together with the relay lens 21, the iris diaphragm 20, the relay lens 19, the half mirror 18, the rotating prism 17, and the half mirror 8, constitute an irradiation optical system that irradiates the eye 1 to be measured with a predetermined pattern of light flux. ing. The iris diaphragm 20 is conjugated with the pupil of the eye 1 to be measured, and the measurement light projection light source 26 is conjugated with the fundus F of the eye 1 to be measured. The rotating prism 17 is always rotated during measurement.

  Measurement light from the measurement light projection light source 26 is projected onto the fundus F of the eye 1 to be measured via the relay lens 21, iris diaphragm 20, relay lens 19, half mirror 18, rotating prism 17, half mirror 8, and objective lens 5. Is done.

  The measurement unit 25 includes a variable cross cylinder 28, an imaging lens 29, a Hartmann plate 30, and a light receiving element 31 as a light receiving unit. The imaging lens 30 functions as a focusing optical member that adjusts the light flux state in order to focus the reflected light from the eye 1 to be measured.

  The Hartmann plate 30 functions as a splitting optical element that splits the measurement light beam from the imaging lens 29 into a plurality of light beams. The variable cross cylinder 28, the imaging lens 29, the Hartmann plate 30, and the light receiving element 31, together with the half mirror 8, the rotating prism 17, the half mirror 18, the relay lens 22, the reflecting mirror 23, and the relay lens 24, have a measuring light receiving optical system. It is composed.

The Hartmann plate 30 is composed of, for example, minute lens plates that are equally spaced, and assuming that parallel light beams are incident on the Hartman plate 30, a lens array image 32 ′ that is equally spaced as shown in FIG. 3 is formed on the light receiving element 31. Is done. The interval between the lens array images 32 ′ is equal to the interval between the minute lens plates. Here, the horizontal axis X corresponds to, for example, the horizontal direction of the eye 1 to be measured, the vertical axis Y corresponds to, for example, the vertical direction of the eye 1 to be measured, and I (x _i , y _i ) is (x _i , y _i). ) Is the light intensity of the lens array image 32 ′ at the point.

  When the measurement light beam from the eye 1 to be measured is incident on the Hartmann plate 30 due to myopia, the image interval of the lens array image 32 ′ becomes narrower than the lattice interval of the minute lens plate, and the Hartmann plate 30 is moved from the eye 1 to be measured. When the measurement light beam is incident due to hyperopia, the image interval of the lens array image 32 ′ becomes wider than the lattice interval of the minute lens plate.

  The video signal of the CCD image sensor 16, the light receiving output of the light receiving element 7b, and the light receiving output of the light receiving element 31 are input to the arithmetic unit 32 shown in FIG. The calculation unit 32 outputs signals to the memory unit 33, the display unit 34, and the control unit 35.

  The control unit 35 outputs a lighting drive signal toward the ring-shaped illumination light source unit 4, the platide ring 4 ′, the illumination LED 6 a, the fixation target light source 9 a, the illumination light source 14 a, and the measurement light projection light source 26. The illumination light source 4, the platide ring 4 ′, the illumination LED 6 a, the fixation target light source 9 a, the illumination light source 14 a, and the measurement light projection light source 26 are appropriately turned on as necessary.

  The control unit 35 also outputs a control drive signal to the first drive unit 36, the second drive unit 37, the third drive unit 38, and the fourth drive unit 39, and the variable cylinder 28 is rotationally driven by the first drive unit 36. Then, the measurement unit 25 is driven back and forth along the optical axis direction (Z direction) by the second drive unit 37, and the fixation target projection optical system 9 is driven back and forth along the optical axis direction by the third drive unit 38. Then, the rotating prism 17 is driven to rotate by the fourth driving unit 39.

  First, as shown in FIG. 5, the optical characteristic measuring apparatus performs alignment adjustment of the eye 1 to be measured (S.21). Next, the calculation unit 32 outputs a command signal to the second drive unit 37 so as to be the reference position, whereby the apparatus main body is set to the reference position with respect to the eye 1 to be measured (S.22). Here, the reference position is a position where the wavefront aberration can be accurately measured when the eye 1 to be measured is a normal eye.

Next, the video signal of the light receiving element 31 is input to the calculation unit 32. Here, the number of light receiving elements 31 is N in the horizontal direction and M in the vertical direction. The luminance value I (x _i , y _j ) of the pixel (x _i , y _j ) of the light receiving element 31 is stored in the memory unit 33 (S.23). Here, the subscript i is a positive integer from 1 to N, and the subscript j is a positive integer from 1 to M.

  Next, the calculation unit 32 proceeds to a point image position detection determination flow S0 (see FIG. 6) for determining whether or not point image position detection is possible (S.24).

In the position detection determination flow S0, the ideal point image position of the kth minute lens of the lens array is set to (H _xk , H _yk ) (S.1). However, k is a positive integer from 1 to L. The calculation unit 32 sets the detection point threshold H _th and sets the set number g _th of detectable conditions (S.2). Next, k = 1 and g = 0 are set (S.3). Next, the computing unit 32 computes the luminance value cd within the range according to the following equation (S.4).

ここで、Ｌはレンズアレイの微小レンズの個数、αは被測定眼１の瞳に対するレンズアレイの倍率、ｄｘ、ｄｙはそれぞれｘ方向、ｙ方向の微小レンズアレイのレンズ間距離、ｐはレンズアレイ像を取得したピクセルのサイズである。

Here, L is the number of microlenses in the lens array, α is the magnification of the lens array with respect to the pupil of the eye 1 to be measured, dx and dy are the distances between the lenses in the x and y directions, and p is the lens array. The size of the pixel that acquired the image.

Next, the calculation unit 32 determines whether or not the luminance value cd is larger than the threshold value H _th (S.5). When the luminance value cd is larger than the threshold value H _th , the process of g = g + 1 is performed (S.6), and it is determined whether k is smaller than L (S.7). When the luminance value cd is equal to or smaller than the threshold value H _{th, S.I.} It moves to 7 as it is. Next, when k is smaller than L, the process of k = k + 1 is performed (S.8), and the process returns to S.4 and the calculation of Formula 1 is performed. These S.4 to S.E. 8 is performed until k becomes equal to L, and when k becomes equal to L, S.E. The process proceeds to 9. The calculation unit 32 is an S.I. In 9, setting the number g of the detection points it is determined whether more than a threshold value g _th, setting the number g of the detection point is at less than the threshold value g _th is determined that the point image undetectable (S.10), detection When the set number g of points is equal to or greater than the threshold value g _th , it is determined that point image detection is possible (S.11).

The calculation unit 32 is the same as that shown in FIG. If the point image cannot be detected in 24, the process proceeds to S.25. The calculation unit 32 is S.I. In S25, spherical power measurement S30 using Fourier transform shown in FIG. 7 is performed. The calculation unit 32 sets the pupil analysis range PE shown in FIG. 3 in the spherical power measurement S30 using Fourier transform (S.31). All other ranges are set to “0”. That is, if (x _i , y _j ) is outside the analysis range PE, I (x _i , y _j ) = 0 is set (S.32).

  Here, the subscript i is a positive integer from 1 to N, and the subscript j is a positive integer from 1 to M. The pupil analysis range PE can be obtained from the spread of the lens array image 32 ′. However, if the diameter is set to 2 mm for clear vision and 6 mm for night vision, the pupil analysis range PE is a value suitable for the condition of the subject. It becomes.

Next, the computing unit 32 performs a discrete Fourier transform on I (x _i , y _j ) based on the following equation (2). Then, a spatial frequency image R (u _i , v _j ) is obtained (S.33).

これにより、図８に示すように、フーリエ変換された空間周波数像３２”が得られる。

As a result, as shown in FIG. 8, a Fourier-transformed spatial frequency image 32 ″ is obtained.

  Next, the calculation unit 32 performs the nearest center-of-gravity point calculation process S40 of the point images existing in the U and V directions (S.34).

That is, as shown in FIG. 9, the calculation unit 32 sets the center O of R (u, v) as the origin of the (u, v) coordinates (S.41 in FIG. 10). Next, the calculation unit 32 calculates the position M _u of the maximum value in the u direction (S.42). Then, the arithmetic unit 32 calculates the center of gravity G _u from pixels near M _u (S.43). Then, the arithmetic unit 32 calculates the distance Δu between the center of gravity G _u and the center (S.44), v calculates the position Mv maximum value in a direction (S.45). Next, the calculation unit 32 calculates the center of gravity G _v from the pixels near M _v and calculates the distance Δv between G _v and the center (S.46).

  Next, the computing unit 32 executes a spherical power calculation process (S.50) estimated from the distance Δv (S.35).

The calculation unit 32 calculates the spherical power DIPO _x in the horizontal direction based on the following formula 3 as shown in FIG. 11 (S.51).

ついで、演算部３２は、縦方向の球面度数ＤＩＰＯ_yを下記の数４式に基づいて算出する（Ｓ．５２）。

Next, the computing unit 32 calculates the spherical power DIPO _y in the vertical direction based on the following formula 4 (S.52).

そして、演算部３２は、球面度数Ｓｆを下記数５式に基づき算出してメモリ部３３に保存する（Ｓ．５３）。

Then, the calculation unit 32 calculates the spherical power Sf based on the following equation 5 and stores it in the memory unit 33 (S.53).

ついで、演算部３２は、バリアブルクロスシリンダ２８を適宜駆動して乱視度数Ｃを下記数６式に基づき算出してメモリ部３３に保存する（Ｓ．５４）。

Next, the calculation unit 32 appropriately drives the variable cross cylinder 28 to calculate the astigmatism degree C based on the following formula 6 and stores it in the memory unit 33 (S.54).

更に、演算部３２は、乱視軸Ａを下記数７式に基づき算出してメモリ部３３に保存する（Ｓ．５５）。

Further, the calculation unit 32 calculates the astigmatic axis A based on the following equation 7 and stores it in the memory unit 33 (S.55).

そして、演算部３２は、球面度数Ｓｆ、乱視度数Ｃ、乱視軸Ａの測定結果を出力する（Ｓ．２６）。

And the calculating part 32 outputs the measurement result of spherical power Sf, astigmatic power C, and astigmatic axis A (S.26).

  FIGS. 12 and 13 are diagrams showing a state in which the measurement result of the spherical power Sf, the astigmatism power C, the astigmatism axis A and the power map obtained in this way are displayed on the screen G of the display unit 34. FIG.

  Then, the calculation unit 32 causes the control unit 35 to move the measurement unit 25 from the reference position in the direction of the optical axis so that the spherical power Sf obtained by the measurement unit 25 becomes 0 (S.27).

  And the calculating part 32 repeats the process of S.23-S.27. In S.24, the calculation unit 32 determines whether the position of the point image can be detected in S.24. If the calculation unit 32 determines that the position of the point image can be detected, the calculation unit 32 shifts to a wavefront aberration measurement process for the eyeball (S.28). Thereby, the precise measurement of the eye to be measured is executed, the calculation result of the precise measurement is output (S.29), and the measurement is completed.

  As described above, the calculation unit 32 obtains the wavefront aberration from the rough measurement mode for obtaining the refractive power of the eye 1 to be measured based on the frequency component of the light receiving position of the light receiving signal indicating the measurement data from the light receiving element 31 and the interval between the light receiving positions. And an optical characteristic of the eye 1 to be measured is calculated. The control unit 33 adjusts and controls the focusing optical member by moving the measurement unit 25 in the optical axis direction based on the refractive power Sf obtained in the rough measurement mode.

  In the embodiment according to the present invention, when the precise measurement by the wavefront aberration measurement process cannot be performed, the measurement unit 25 is moved in the optical axis direction so that the substantially parallel light beam enters the Hartmann plate 30. And because it is used for precise measurement by wavefront aberration, a wide range of optical characteristics of the eye can be used without adopting a structure that adds a dedicated optical system for coarse measurement to the optical system for precise measurement of optical characteristics. The structure of the entire apparatus can be simplified and the cost can be reduced.

  In addition, since the calculation by the wavefront aberration measurement processing is known, the description thereof is omitted.

It is an optical diagram of the optical characteristic measuring apparatus concerning this invention. It is a figure which shows the anterior ocular segment image displayed on the screen of the display part concerning this invention. It is a figure which shows an example of the lens array image obtained by the light receiving element concerning this invention. It is a block circuit diagram of the optical characteristic measuring apparatus concerning this invention. It is a figure which shows the measurement flowchart of the optical characteristic measuring apparatus concerning this invention. It is a figure which shows the position detection determination flowchart of a point image. It is a spherical power measurement process flowchart. It is a figure which converts and shows a lens array image to spatial frequency distribution. It is explanatory drawing which shows an example of a gravity center calculation process, Comprising: It is an enlarged view of the center point vicinity part of UV space shown in FIG. It is a flowchart of a gravity center calculation process. It is a flowchart of a spherical power calculation process. It is the figure which displayed on the screen an example of the eye refractive power value obtained by the rough measurement mode concerning this invention, and its power map. It is the figure which displayed on the screen the other example of the eye refractive power value obtained in the rough measurement mode concerning this invention, and its power map.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Eye 3 to be measured ... Light-receiving optical system 26 ... Light source part 29 ... Focusing optical member 30 ... Split optical element 31 ... Light-receiving part 31
32. Calculation unit

Claims (3)

  An irradiation optical system including a light source unit that irradiates a light beam to be measured with a predetermined pattern, a focusing optical member that adjusts a light beam state in order to focus reflected light from the eye to be measured, and the focusing optical member A light receiving optical system including a light receiving unit that receives light from a split optical element that divides the light beam from the light receiving unit into a plurality of light beams, and a frequency component of a light receiving position of a light receiving signal indicating measurement data from the light receiving unit. A calculation unit for calculating optical characteristics of the eye to be measured having a rough measurement mode for calculating refractive power and a precise measurement mode for calculating wavefront aberration from the interval between light receiving positions; and a refractive power obtained in the rough measurement mode. And a control unit that adjusts and controls the focusing optical member based on the optical characteristic of the eye based on data obtained in a precise measurement mode performed by the arithmetic unit after being controlled by the control unit. Characteristic measuring device.   The irradiation optical system forms a substantially point light source as a predetermined pattern on the fundus of the eye to be measured, and the split optical member of the light receiving optical system splits the reflected light from the eye to be measured into a plurality of light beams. The optical characteristic according to claim 1, wherein the light reception signal from the light receiving unit corresponds to a Hartmann image, and the display unit graphically displays a refractive power distribution or a power map of the eyeball of the eye to be measured. measuring device.   In an optical characteristic measurement apparatus having a split optical member, an irradiation optical system including a light source unit that irradiates a light to be measured with a predetermined pattern of light, and a split optical element that splits reflected light from the eye to be measured into a plurality of light beams A light receiving optical system including a light receiving unit that receives light through the light receiving unit, and a rough measurement mode that obtains the refractive power of the eye to be measured based on the frequency component of the light receiving position based on a light receiving signal indicating measurement data from the light receiving unit. An optical characteristic measuring apparatus that calculates an optical characteristic of an eye based on a refractive power obtained in the rough measurement mode and a calculation unit that calculates an optical characteristic of the measurement eye.

Images