JP3438789B2 - Living eye measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a measurement light beam emitted from a light source having a short coherence length toward an eye to be inspected and divides a part of the measurement light beam to refer to a reference reflecting surface corresponding to the eye to be inspected. Guided as light, the fundus position measured by an interference optical system having an interference signal obtained by interfering the measurement reflected light from the eye to be examined and the reference reflected light from the reference reflection surface corresponding to the eye, and the corneal position The present invention relates to an improvement of a living eye measuring device that measures an eye to be inspected based on a corneal vertex position measured by a measuring system.

[0002]

2. Description of the Related Art A measuring light beam emitted from a light source having a short coherence length is directed toward an eye to be inspected, and a part of the measuring light beam is divided and guided as a reference light to a reference reflecting surface corresponding to the eye to be inspected. The fundus position measured by an interference optical system having an interference signal obtained by interfering the measurement reflected light from the optometry and the reference reflected light from the reference reflection surface corresponding to the subject eye,
There is known a living eye measuring device that measures an eye to be inspected based on a corneal vertex position measured by a cornea position measuring system.

In this conventional biological eye measuring apparatus, the refractive power is corrected by moving the refractive power correction lens in the optical axis direction together with the alignment operation. Further, in order to confirm the level of the interference signal at that time, a measuring device such as an oscilloscope is connected to the outside, and the examiner constantly measures the waveform of the interference signal to measure the living eye.

[0004]

However, in this conventional biological eye measuring apparatus, the examiner observes the waveform of the interference signal with a measuring instrument such as an oscilloscope connected to the outside during measurement and confirms the level. However, since the device optical system is aligned with the eye to be examined, it leads to diverting the line of sight from the display unit for anterior segment observation, and there is a problem that it is difficult to improve alignment operability and speed up measurement. .

Further, the examiner cannot know where the refracting power correction lens is located in the refracting power correction range during the measurement, and cannot confirm whether the refracting power is properly corrected, or the lens of the crystalline lens cannot be confirmed. Depending on the turbidity, there is a problem that it is difficult to obtain an interference signal due to a slight misalignment, which makes measurement difficult.

The present invention has been made to solve the above-mentioned drawbacks of the conventional apparatus, and an object of the present invention is to provide a living eye measuring apparatus capable of performing alignment operation of the optical system of the apparatus quickly and easily. .

[0007]

A living eye measuring apparatus according to the present invention irradiates an eye to be inspected with a measurement light beam emitted from a light source having a short coherent length, and divides a part of the measurement light beam to divide the object to be measured. Guided as reference light to the reference reflective surface for optometry,
A fundus position measured by an interference optical system having an interference signal obtained by interfering the measured reflected light from the eye to be examined and the reference reflected light from the reference reflecting surface corresponding to the eye, and the corneal position measurement system. in a living eye measuring device performs measurement of the eye by the corneal vertex positions, for alignment operation of the apparatus optical system, a display based on the interference waveform, close to this
Display of the anterior segment for observing the anterior segment of the eye to be inspected, and
Alignment aiming position in anterior eye image measured in the past
Characterized in that the display means for displaying the provided.

The living eye measuring apparatus of the present invention is characterized in that the display means is provided integrally with the monitor.

The living eye measuring apparatus of the present invention is characterized in that the interference signal waveform itself is displayed on the display means.

Further, the living eye measuring apparatus of the present invention is characterized in that the display means displays the correction value of the refractive power correction section within the refractive power correction range.

The living eye measuring apparatus of the present invention is characterized in that the display means displays all alignment aiming positions of the anterior segment images measured in the past.

The living eye measuring apparatus of the present invention is characterized in that the alignment direction toward the peak value is displayed before and after the peak value of the interference signal.

[0013]

In the living eye measuring apparatus of the present invention, the display means
Interference for the alignment operation of the device optical system in
An anterior eye for observing the anterior segment of the eye to be examined near the waveform-based display
Display of the part and the error in the anterior eye image measured in the past.
Element aiming position is displayed.
The alignment operation can be performed without taking the eyes off.
In addition, the alignment operation of the optical system of the device is displayed by the display means.
Display based on interfering waveforms for work, placed near it
Display of anterior segment for anterior segment observation and past
Of the alignment aiming position in the anterior segment image measured at
Since the display is performed, it is possible to save space in the display means.
You can Furthermore, in the anterior segment image measured in the past
You can see the alignment aiming position
The alignment position can be easily recognized and the alignment
To improve the operability of the measurement and to speed up the measurement of the eye.
You can

Further, in the biological eye measuring device of the present invention, since the monitor and the display means are integrally provided, the space of the display portion can be saved, and the alignment operation is further facilitated. .

In the living eye measuring apparatus of the present invention, the level of the interference signal can be easily recognized by directly looking at the waveform of the interference signal.

Further, in the living eye measuring apparatus of the present invention, since the correction value of the refractive power correction unit can be viewed, the refractive power of the eye to be inspected can be easily recognized.

Further, in the living eye measuring apparatus of the present invention, since all the alignment aiming positions of the anterior segment images measured in the past can be seen, it is possible to easily recognize an appropriate alignment position.

Further, in the living eye measuring apparatus of the present invention, since the alignment direction can be known, the alignment operation becomes simpler.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Each embodiment of the living body eye size measuring apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the measuring apparatus according to the present invention. In FIG. 1, 100 is a cornea position measuring system (ring image projection image receiving optical system), 101 is an interference optical system that is a fundus position measuring system, and 102 is a ring-shaped light source projection as an irradiation optical system that irradiates a cornea to be examined with a light beam. Part, 10
Reference numeral 3 is an eye to be inspected, and 104 is an objective lens.

FIG. 2 shows the two-dimensional image sensor 1 shown in FIG.
It is a figure which shows the ring image formed in 07. The configuration of the ring image projection / image receiving optical system 100 is almost the same as that of Japanese Patent Laid-Open No. 4-35637, and therefore its explanation is omitted.

The interference optical system 101 includes a laser diode 1
30, lens 133, pinhole 134, beam splitter 135, lens 136, focusing lens 137, collimating lens 138, total reflection mirror 172, model eye unit member 173, pinhole 140, lens 141, and photosensor 142. The laser diode 130 has a low coherence length, and the coherence length is, for example, 0.05 mm to 0.1 mm. The laser light emitted from the laser diode 130 is reflected by the lens 1
It is focused on the pinhole 134 by 33. The pinhole 134 serves as a quasi-point light source. As the light source, an LED or the like having a narrow spectrum width may be used instead of the laser diode.

The laser light passing through the pinhole 134 is
The beam splitter 135 splits the light beam toward the lens 136 and the light beam toward the collimator lens 138. The lens 136 constitutes the measurement optical path 171 together with the focusing lens 137 and the dichroic mirror 115. The collimating lens 138 is a total reflection mirror 172,
A reference optical path 174 is configured with the model eye unit member 173.

The lens 136 plays a role of collimating the laser light passing through the pinhole 134. Lens 1
The laser light collimated by 36 is guided to the focusing lens 137 as a measurement light beam. Focusing lens 137
Is movable in the optical axis direction and serves as a refractive power correction member for the subject's eye 103. Focusing lens 13
7 is moved by the focusing lens drive unit 200, and the amount of movement of the focusing lens 137 is detected by counting the output signal of an encoder that outputs a pulse train in accordance with the rotation of the motor of the drive unit 200, for example, and detects it from the count number. It is assumed to be configured. The measurement light flux that has passed through the focusing lens 137 has a dichroic mirror 115 and an objective lens 104.
It is guided to the eye 103 to be inspected via and is converged on the fundus 152 by performing the refractive power correction described later.

The focusing lens 137 functions to collimate the fundus reflected light, and the collimated fundus reflected light is
It is relayed to the pinhole 140 via the lens 136 and the beam splitter 135. The pinhole 140 is conjugate with respect to the reflecting surfaces of the pinhole 134 and the beam splitter 135, and the spotlight on the fundus 152 is conjugate with the pinhole 134. Therefore, the alignment of the measuring device with respect to the eye 103 is slightly shifted. However, the fundus reflected light can pass through the pinhole 140.

The laser light collimated by the collimator lens 138 is guided to the model eye unit member 173 by the total reflection mirror 172. The model eye unit member 173 is movable in the optical axis direction so that the optical path length of the reference optical path 174 and the optical path length of the measurement optical path 171 are the same. The model eye unit member 173 includes the lens 17
5, a reflecting mirror 176, and a movable frame 177. The model eye unit member 173 is used to eliminate the deflection of the reflected light flux due to the blurring that occurs with its movement, and in principle a simple movable mirror may be used. The reference light flux reflected by the reflection mirror 176 follows the same optical path, passes through the beam splitter 135, is combined with the measurement light flux, and is relayed to the pinhole 140. The light flux passing through the pinhole 140 is the lens 1
It is converged on the photo sensor 142 by 41.

By moving the model eye unit member 173,
When the optical path difference between the reference optical path 174 and the measurement optical path 171 becomes equal to or less than the coherent length of the laser diode 130, the reference light flux and the measurement light flux interfere with each other, and the model eye unit member 1
An interference signal corresponding to the moving speed of 73 and the oscillation wavelength of the laser diode 130 is obtained. Then, for example, the model eye unit member 173 is driven at a speed of about 10 reciprocations per second so that the interference signal can be repeatedly observed. The interference waveform changes sinusoidally every time the optical path difference between the reference optical path 174 and the measurement optical path 171 changes by one wavelength of the oscillation wavelength of the laser diode 130, and the optical path length between the reference optical path 174 and the measurement optical path 171 changes. When equal, the strongest interference is obtained. That is, the optical path length of the reference optical path 174 when the strongest interference is obtained is equal to the optical path length of the measurement optical path 171,
The position of the reflection mirror 176 of the model eye unit member 173 is at the same position as the fundus 152 with respect to the reflection surface of the beam splitter 135.

As shown in FIG. 3, the output of the photo sensor 142 is input to the waveform shaping circuit 178 via the amplifier 150, the peak position of the interference signal is detected, and the reflection mirror of the model eye unit member 173 at the peak time is detected. From the position of 176, the position of the fundus 152 can be measured. Here, the coherence length of the laser diode 130 is set to 0.1.
Assuming mm, the detection of the peak position of the interference signal can be determined with a resolution of a fraction of 0.1 mm, which is the coherent length, and sufficient accuracy can be obtained for measuring the intraocular dimension.

Next, the details of the signal processing will be described with reference to FIGS.

The measurement light beam as the reflected light from the fundus 152 is weaker than the reference light beam and has a light amount difference. However, since both light fluxes are interfered with each other and measured as an interference signal, it is possible to remove a noise component based on the dark current of the photosensor 142 and efficiently detect the signal component. Therefore, the amplifier 150 includes the photo sensor 1
Only the AC component of the interference signal 42 is amplified.

The interference signal C4 obtained at this time has an AC waveform centered on 0 V as shown in FIG. 4, but since it is buried in random noise such as shot noise, the interference signal C4 can be obtained as it is. It is difficult to detect the position of the model eye unit member 173 when standing. But,
The frequency f of the interference signal C4 is determined by the model eye unit member 173.
Moving speed V of the laser diode and the oscillation wavelength λ0 of the laser diode 130
Is determined by the following equation.

F = 2 · V / λ 0 Here, if the movement amount of the model eye unit member 173 is appropriately set, the movement speed V during measurement may be considered to be constant, and the frequency f can be set as a device constant. .

Therefore, only the signal component can be extracted from the random noise by passing the interference signal C4 through the bandpass filter (BPF) 179 matched with the frequency f in the above equation. If the moving speed V cannot be kept constant, a bandpass filter 179 may be used instead of a tracking filter adapted to the change in moving speed.

Reflection mirror 1 of model eye unit member 173
When the position X of 76 is plotted on the horizontal axis and the output voltage of the photo sensor 142 is plotted on the vertical axis, the interference signal C4 is obtained from the bandpass filter 179. The interference signal C4 is a full wave rectification circuit 18
0 and is shaped into the rectified waveform C5 shown in FIG.
The rectified waveform C5 is input to the smoothing circuit 181, and the smoothed waveform C6 shown in FIG. 6 is obtained.

The smoothed waveform C6 is the peak hold circuit 18
It is input to the comparison circuit 183 via 2 and is directly input to the comparison circuit 183. Peak hold circuit 182
Holds and outputs a voltage lower than the smoothed waveform C6 by .DELTA.V as a peak voltage. Therefore, the peak hold circuit 1
82 outputs a waveform C7 as shown in FIG. The comparison circuit 183 compares the waveform C6 with the waveform C7 and outputs the waveform C7.
The output changes from L to H at the position X0 where the waveform becomes larger than the waveform C6, and the step signal C8 is output.

Here, if ΔV is sufficiently smaller than the output peak level V of the smoothed waveform C6, d as the amount of deviation from the original peak position Xp of the inversion position X0 of the output signal of the comparison circuit 183 is sufficient. It may be considered small, and the position X0 of the model eye unit member 173 when the output signal of the comparison circuit 183 is inverted is the position of the model eye unit member 173 when the interference is strongest (when the interference signal is at the peak). (The position of the model eye unit member 173).

The output signal of the comparison circuit 183 is input to the latch circuit 184 and the control circuit 157. The model eye unit member 173 is driven by the unit driving unit 185,
The position detection circuit 186 is configured to be able to detect the position data. The latch circuit 184 latches the position data of the position detection circuit 186 indicating the movement amount of the model eye unit member 173.

The position detection circuit 186 counts the output signal of the encoder that outputs a pulse train in accordance with the rotation of the motor of the unit driving section 185, and detects the movement amount of the model eye unit member 173 from the counted number. do it. Further, the output signal of the linear encoder directly set on the model eye unit member 173 may be counted.

Therefore, the latch circuit 184 outputs the interference signal C
The position data of the model eye unit member 173 when 4 appears most strongly is saved. The position data is calculated by the calculation unit 158.
And the distance from the reference position to the fundus 152 is measured. Further, as described in JP-A-4-35637, since the distance from the reference position to the apex 120P of the cornea can be measured by the cornea position measuring system 100, the intraocular dimension is measured from both measurement results. be able to.
The measurement result is displayed on the display unit 164.

Here, both of the measurements need to be performed simultaneously in order to remove the influence of the slight movement of the eye 103, but the output signal of the comparison circuit 183 is used as the start signal of the corneal position measuring system 100 to control it. Simultaneous measurement can be performed by taking in the data of the ring images i1 and i2 of the two-dimensional image sensor 107 into the frame memory 163 at the same time that the circuit 157 detects the start signal.

A band pass filter 179, a full wave rectifier circuit 180, a smoothing circuit 181, a peak hold circuit 182,
The waveform shaping circuit 178 including the comparison circuit 183 functions as a start signal generation unit of the corneal position measurement system 100.

Next, the correction of the refractive power will be described.

This measuring apparatus corrects the refractive power of the eye 103 to be examined together with the alignment operation. The refractive power correction is
There is no need to readjust once for the eye 103 to be inspected, and even if the alignment of the device is not perfect, correction can be performed if roughly performed, and alignment of the device is difficult. Absent.

In this refractive power correction, the reflected light flux from the fundus 152 is combined with the reflected light flux from the reflection mirror 176 of the model eye unit member 173 to form an interference signal.
Since the reflected light flux from the reflection mirror 176 has a constant light quantity, the amplitude amount of the interference signal changes depending on the light quantity of the reflected light from the fundus 152. That is, it can be considered that when the amplitude amount of the interference signal becomes maximum, the reflected light from the fundus 152 becomes maximum, and the refractive power of the eye 103 to be inspected is corrected. Therefore, by observing the interference signal obtained from the photo sensor 142 and moving the focusing lens 137 in the optical axis direction, it is possible to correct the tropic force with respect to the eye 103 to be inspected.

The means for displaying the change in the smooth waveform C6 associated with the movement of the focusing lens 137 will be described below.

In the present embodiment, as shown in FIG. 3, part of the smoothed waveform C6 is also input to the S / H (sample and hold) circuit 300 and sampled based on the clock signal by the clock generation circuit 301.

The sampling output is the A / D converter 302.
Is input to and digitized into the wave memory 303.
Are sequentially input to. Next, the contents of the wave memory 303 are sequentially read out, processed by the waveform calculation circuit 304 as required, and displayed on the display unit 170a of the anterior segment observation monitor television 170 via the display control circuit 305 as shown in FIG. The smooth waveform C6 is displayed on. Further, it may be output to a printer (not shown) or the like, if necessary.

As a result, the examiner can always observe the waveform of the smooth waveform C6 without diverting the line of sight from the monitor television 170, and while confirming the level, align the optical system of the apparatus with the eye 103 to be examined. .

Further, in the case of a cataract eye in which the crystalline lens is opaque in the center of the optical axis of the eye to be inspected, the alignment may be moved in the vertical and horizontal directions in order to perform measurement in the peripheral portion where the opacity is relatively small. . At that time, fine movement of XY alignment (alignment of the optical system of the apparatus with respect to the eye 103 to be inspected) is performed within a range in which the displacement of the alignment is allowed, and the level is confirmed while observing the waveform of the smooth waveform C6. Good.

For a detailed description of the fundus position measurement and the cornea position measurement system 100 by the interference optical system 101, refer to Japanese Patent Laid-Open No. 4-35637.

In this embodiment, a focusing lens moving section 200 for moving the focusing lens 137 is provided.
The focusing lens moving unit 200 temporarily moves the focusing lens 137 within a predetermined range when correcting the refractive power, and stores the position of the focusing lens 137 when the output from the peak hold circuit 182 becomes maximum. Every time, then focus lens 1
The refractive power is corrected by moving 37 to the storage position.

Then, the refracting power of the subject's eye 103 is obtained from the moving amount of the focusing lens 137 at that time, and as shown in FIG.
An eye 103 to be inspected is displayed on the display unit 170a of the monitor TV 170.
The position of the focusing lens 137 indicating the refracting power of is displayed. Further, it may be output to a printer (not shown) or the like, if necessary.

As a result, the examiner can always grasp the position of the focusing lens 137 and the refraction value of the eye 103 to be inspected, and while confirming that the appropriate refraction power correction is performed, the examiner's optical system for the eye 103 is inspected. Alignment can be done.

A pulse motor is used as the motor of the focusing lens moving unit 200, and the focusing lens 13 corresponding to the number of input pulses is used.
The configuration may be such that the movement amount of 7 is detected. In addition, the output signal of the encoder that outputs a pulse train is counted in accordance with the rotation of the motor of the focusing lens moving unit 200, and the movement amount of the focusing lens 137 is detected from the count number, or is directly set on the focusing lens 137. A configuration may be adopted in which the amount of movement is detected by counting the output signals of the linear encoders.

Next, the display of the alignment position will be described.

In this embodiment, the center of the ring image i2 formed on the two-dimensional image sensor 107 is equal to the optical axis of the interference optical system 101, and the preset reference position and ring image are set. The displacement amount of the alignment position is detected from the center position of the ring image i2 obtained during the pattern analysis, and the alignment aiming position P is continuously displayed on the display section 170a of the monitor television 170 as shown in FIG.

Alternatively, as shown in FIG. 11, an alignment position detecting light source 311 is provided so as to be coaxial with the optical axis of the interference optical system 101, and the alignment position detecting optical system 3 is provided.
Make up 30. This alignment position detection optical system 33
Reference numeral 0 indicates an alignment position detecting light source 311 and a lens 31.
2, pinhole 313, lens 314, diaphragm 315, lens 316, half mirror 317, half mirror 31
8, a lens 319, a lens 320, and a two-dimensional position detection element (PSD) 321. The light flux emitted from the alignment position detection light source 311 is condensed on the pinhole 313 by the lens 312. The light flux passing through the pinhole 313 is collimated by the lens 314, passes through the diaphragm 315, the lens 316, and the half mirror 317,
It is relayed to the focal position of the objective lens 104. afterwards,
Dichroic mirror 11 via half mirror 318
5. The parallel light flux is guided to the subject's eye 103 via the objective lens 104, and a virtual image is formed at a position of half the corneal curvature of the subject's eye.

The reflected light from the cornea 120 of the eye to be examined follows the same optical path, passes through the half mirror 317, the lens 319,
It is guided to the two-dimensional position detecting element 321 by the lens 320. The output of the two-dimensional position detection element 321 is the position calculation circuit 3
22 is input. After that, by pressing a measurement switch (not shown), the coordinate value indicating the alignment aiming position can be obtained as the calculation result. Then, the alignment aiming position P obtained as shown in FIG. 10 is displayed on the display unit 170a of the monitor television 170. Further, it may be output to a printer (not shown) or the like, if necessary.

As a result, the examiner always monitors the monitor TV 17
The alignment of the optical system of the apparatus with respect to the eye 103 to be inspected is performed while checking the presence or absence of the interference signal due to the alignment deviation or the opaque portion of the eye lens to be inspected, using the alignment aiming position P continuously displayed on the display unit 170a of 0 as a guide. be able to.

That is, even if the opacity of the eye lens to be examined is concentrated on a specific part and the interference signal is difficult to confirm, the alignment aiming position P is used to intentionally avoid an alignment position that is difficult to measure. can do.

Before and after the peak value of the interference signal, the display unit 170 indicates the alignment direction toward the peak value.
By displaying in a, the operability of alignment can be improved.

[0062]

As described above, according to the living body eye measuring apparatus of the present invention, the alignment of the apparatus optical system in the display means is performed.
Near the display based on the interference waveform for
Display of the anterior segment for observing the anterior segment of the eye and measurement in the past
The alignment target position in the captured anterior image is displayed.
Therefore, the alignment is performed without taking the eyes off the display means.
The operation can be performed. In addition, the display means
Based on interference waveforms for alignment operations of stationary optics
Display for viewing the anterior segment of the eye to be inspected
Display on the anterior segment and the image of the anterior segment measured in the past.
The alignment target position is displayed,
Space saving of steps can be achieved. In addition, measured in the past
See the alignment aiming position in a fixed anterior segment image
Therefore, it is easy to recognize the proper alignment position.
Can be identified, there is an effect that can result in a rapid improvement in alignment usability and the subject's eye measurement.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a living eye size measuring device of the present invention.

FIG. 2 is an explanatory diagram showing a ring image formed on a two-dimensional image sensor.

FIG. 3 is a circuit diagram of a main part of the living body eye size measuring apparatus of the present invention.

FIG. 4 is an interference waveform diagram.

FIG. 5 is a full-wave rectified waveform diagram of an interference waveform.

FIG. 6 is a smooth waveform diagram of a full-wave rectified waveform.

FIG. 7 is a diagram showing a smooth waveform, a peak hold waveform, and a step signal waveform.

FIG. 8 is an explanatory diagram showing a first display example of a monitor television.

FIG. 9 is an explanatory diagram showing a second display example of the monitor television.

FIG. 10 is an explanatory diagram showing a third display example of the monitor television.

FIG. 11 is a block diagram of an optical system for detecting an alignment aiming position.

[Explanation of symbols]

100 Corneal position measurement system 101 Interferometric optical system 103 eye 130 Laser diode (light source) 137 Focusing lens (refractive power correction component) 142 Photo sensor (light receiving part) 170 Monitor TV (monitor) 170a Display unit (display means)

Claims (6)

(57) [Claims] 1. A measurement light beam emitted from a light source having a short coherence length is irradiated toward an eye to be inspected, and a part of the measurement light beam is divided and guided to a reference reflection surface corresponding to the eye as reference light, The fundus position measured by an interference optical system having an interference signal obtained by interfering the measurement reflected light from the optometry and the reference reflected light from the reference reflection surface corresponding to the subject eye,
In a living eye measurement device that measures the eye to be inspected based on the corneal apex position measured by the corneal position measurement system, a display based on the interference waveform for alignment operation of the optical system of the device, and a test object placed near this For anterior segment observation
Of the anterior segment of the eye and the anterior eye image measured in the past.
Display means for displaying the alignment aiming position
A living eye measuring device, which is provided . 2. The living eye measuring apparatus according to claim 1, wherein the display unit is provided integrally with the monitor. 3. The living eye measuring apparatus according to claim 1, wherein the display means displays the interference signal waveform itself. 4. The living eye measuring apparatus according to claim 1, wherein the display means displays the correction value of the refractive power correction unit within the refractive power correction range. 5. The living eye measuring apparatus according to claim 1, wherein all of the alignment aiming positions of the anterior segment images measured in the past are displayed on the display means. 6. The living eye measuring apparatus according to claim 1, wherein an alignment direction toward the peak value is displayed before and after the peak value of the interference signal.