JPS6131154A - Apparatus for detecting beam shift - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is used, for example, to align a laser device for ophthalmic treatment, and is capable of detecting beam deviation between an aiming beam for focusing and a main laser beam for treatment. It is related to the device.

Eye treatment laser devices that have recently been used for eye surgery generally focus high-energy, short-pulse light such as a YAG laser on the treatment target area, and destroy the tissue in the treatment target area using an electric field. This is what I did, but
There is a need to destroy target tissues and promote plasma generation with lower energy to eliminate adverse effects on posterior tissues. For this purpose, it is necessary to narrow down the main laser beam to a smaller spot diameter and to make its depth of focus shallower.

Conventionally, high-power, short-pulse YAG lasers have been commonly used as the main laser for treatment, but this is not suitable for aiming because the light is invisible to the naked eye. The aiming beam uses He, which is visible light.
-Ne laser is used. Then, a method is adopted in which the main laser beam for treatment and the aiming beam are made to match, and the aiming beam is used to perform alignment with respect to the treatment target area, and then the main laser beam is emitted. In this case, the important conditions are that the focus position can be easily detected with high precision using the aiming beam, and that there is no misalignment between the aiming beam and the main laser beam.

Various methods have been developed and put into practical use for detecting the focus position, but conventionally, the mismatch between the aiming beam and the main laser beam has been determined using a method similar to visual inspection. Therefore, it was not possible to accurately detect beam deviation.

An object of the present invention is to quantitatively and accurately measure beam deviation in a device that uses two or more beams of different shapes in alignment, such as the aiming beam and main laser beam of a laser device for ophthalmic treatment. The purpose is to provide a beam deviation detection device that enables appropriate processing.The gist of the device is to provide a beam deviation detection device that can perform appropriate processing. a beam position detecting means disposed in the beam position detecting means, an integrating circuit for integrating a photocurrent of a photoelectric conversion element having a position detecting function included in the beam position detecting means, and controlling an integration time of the integrating circuit according to different beams. The present invention is characterized by comprising a control circuit.

The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows an embodiment in which the present invention is applied to a laser device for ophthalmic treatment, where E is the affected area to be treated;
e represents treated presbyopia. In FIG. 1, an ordinary slit lamp having an optical axis 01 is constituted by the objective lens l and the observation optical system 2, and the observation optical system 2 is connected to the objective lens 1.
From the side: variable image magnification optical system 3, relay lens 4. It has a binocular prism 5 and an eyepiece lens 6, and a filter 7 that absorbs the reflected light of the laser beam is arranged to assist the observation optical system 2 in order to protect the treated presbyopia e.

The main laser 8 that emits the main laser beam B1 used for treatment is generally a YAG laser, but other lasers such as ruby, Y
LF, alexandrite laser, etc. can also be used. In addition, the sub laser 9 for the purpose of aiming for focusing and positioning is usually) Is-Ne.
A laser is used, and an aiming beam B2 emitted from the sub laser 9 is reflected by a total reflection mirror 10 and matched with the main laser beam B1 by a beam matching means 11. This beam matching means 11 is a main laser beam B.
For example, a cube reflector, a pellicle reflector, a half mirror, etc. is used, which has a spectral characteristic of transmitting Q of about a few percent for 1 and reflecting a portion of the beam for the aiming beam B2.

The matched beam matched by the beam matching means 11 is expanded by a beam expansion optical system 12 on the optical axis 02, passes through a filter 13, and is reflected by a dichroic mirror 14 arranged on the optical axis 01. The objective lens 1 focuses the light onto the treatment target area Ea of the affected area E. here,
Guicroic Mirror 141t Main 1z-Ther Beam B1
It has spectral characteristics of total reflection for the aiming beam B2, partial transmission for the aiming beam B2, and transmission for visible light other than the aiming beam B2.

The filter 13 consists of a fixed upper plate having a ring-shaped aperture and a rotating lower plate having two or more apertures, and for the main laser beam B1, the total luminous flux passing through the beam expansion optical system 12 is For the aiming beam B2, only the light beams passing through the two or more apertures are transmitted. Here, the farther the imaging point is from the object to be examined, the more
The light flux that has passed through the two or more apertures rotates with a traditional radial locus of movement, but when it coincides with the subject, the locus of movement disappears and it appears as a fixed point. That is, the objective lens 1 and the observation optical system 2 locate the treatment target area Ea of the affected eye E, and the device is configured so that the multiple aiming beams B2 that appear to be rotating become one, and the rotation disappears and stops. After moving and focusing, the main laser 8 is triggered to emit sporadic main laser beams B1 to destroy the treatment target area Ea.

The above is the basic configuration of the laser device for ophthalmic treatment.1 In the present invention, the beam position detection means detecting each position of the aiming beam B2 and the main laser beam Bl that are matched by the beam matching means 11 is used to match the beams. It is provided in the later optical system.

As an example of this beam position detection means, in the embodiment, a photoelectric conversion element 15 that detects the spot position of the main laser beam B1 that passes through the beam matching means 11 and emerges on the optical axis 03, and this photoelectric conversion element 15 The circuit illustrated in FIG. 3 related to this is used.

The photoelectric conversion element 15 has, for example, sections 15a to 15d divided into four rhomboids as shown in FIG.
If the x and y coordinates are taken with the center coincident with the origin as the origin, the rotational displacement of the main laser 8 in the direction of the arrow becomes a movement in the y direction on the photoelectric conversion element 5. If a cube reflector or a pellicle mirror is used as the beam matching means 11, the beam deviation on the optical axis 02 and the beam deviation on the optical axis 03 will match.

Furthermore, even if a thick mirror is used as the beam matching means 11, the beam deviations will match if corrected in advance.

As for the spectral characteristics of the beam matching means 11, its reflection transmittance can be determined according to the powers of the aiming beam B2 and the main laser beam 81 and the sensitivity of the photoelectric conversion element 15.

Although the principle of spot position detection using the photoelectric conversion element 15 has been widely known, the principle will be explained with reference to FIGS. 2 to 4. The spot coordinates (x, y) is obtained. Note that if both spot positions are memorized during adjustment, it is not necessary that the two spot positions match on the photoelectric conversion element 15. During adjustment, the other beam can be blocked and the beam positions can be determined individually. However, during actual operation, measurements are performed as described below. That is, the difference in the power of two people 1a-1c, I in the subtraction circuits 16 and 17, respectively.
At the same time as calculating b-Id, the addition circuit 18 calculates the sum of the four human forces 1a+Ib+Ic+Id, and outputs them to the integral/sample hold circuit 19°20.21.

As will be described in detail later, the integration period has different time widths for the aiming beam 82 and the main laser beam B1, and this time width is controlled by the signal S from the timing controller 22.

The bolded outputs of the integration/sample-and-hold circuits 19, 20, and 21 are converted into time series by the multiplexer 23,
It is converted into a digital signal by the A/D conversion circuit 24 and sent to the CPU 2.
It will be incorporated into 5. The CPU 25 performs calculation and determination processing, and the result is displayed on the display device 26. The display methods include the absolute position of the beam, the deviation from the time of beam adjustment, the relative deviation of the two beams B1 and B2, the change over time of the relative deviation, or the case where the relative deviation exceeds the reference value. This can take various forms, such as a warning display.

Figure 4 shows the sum of each output! This shows an example of a %radial shape, and the power Pa of the aiming beam B2 and the power Pma of the main laser beam B1 differ by about 108 in level. Furthermore, while the aiming beam B2 is a continuous beam, the main laser beam B1 is a pulsed beam with a pulse width of about 10@-8 seconds, which can be considered to be a short emitted beam. For that purpose, beam B
1. For B2, the same circuit is used and the S/N is the same.
To measure this, it is necessary to integrate the output of the photoelectric conversion element 15 and make the outputs similar in magnitude. It is fine as long as it is selected.

The timing controller 22 receives a command from the CPU 25 and gives a timing pulse to each circuit, but since the photoelectric conversion element 15 normally monitors the aiming beam B2, the signal S from the timing controller 22 is equal to the integration time Ta of the aiming beam B2. It has become. When a command to emit the main laser beam Bl is received, a trigger signal t is output as shown in Fig. 4 to the circuit 27 shown in Fig. 143 for emitting the main laser beam Bl, and then the signal S is integrated. Change to time TV. Then, the aiming beam B2 and the main laser beam B1 are measured separately in time.

In the embodiment described above, an example of position detection using the photoelectric conversion element 15 divided into four rhomboids was shown, but the photoelectric conversion element 1
For example, a position sensor or a two-dimensional COD having a position detection function may be used instead of the sensor 5.

FIG. 5 shows a second embodiment, in which the same reference numerals as in FIG. 1 represent the same or equivalent members. In this embodiment, after matching by the beam matching means 11, a part of the light is guided to the photoelectric conversion element 15 using another half mirror 28 arranged on the optical axis 02. In this case, the beam matching means 11 has a characteristic of transmitting the aiming beam B2 and totally reflecting the main laser beam B1, and the half mirror 28 has a characteristic of partially reflecting both beams. Normally, beam matching is adjusted by rotating the mirror 10 and the beam matching means 11, but in FIG. 5, compared to the case of FIG. Since it is small, it has the advantage of being easy to adjust.

Furthermore, in the embodiments shown in FIGS. 1 and 5, if the mirror 10 and the beam matching means 11 are electrically adjustable mechanisms,
By using the displacement information obtained according to the displacement of both beams B1 and B2, it is possible to automatically correct the displacement by rotating these beams. Since the amount of deviation of the beam spot in the photoelectric conversion element 15-F depends on the distance from the part that caused the deviation to the photoelectric conversion element 15, in order to make the device compact, it is necessary to The distance from the half mirror 28 to the photoelectric conversion element 15 cannot be increased, and there is a possibility that sufficient resolution cannot be obtained.

In order to improve this problem, as shown in FIG.
If the reduction optical system 29 is disposed between the angles 5 and 5, the deviation angle α is enlarged to β, so that the resolution can be increased and the distance can be reduced. In this case, the relationship α/β=reduction ratio is established.

Furthermore, the total output 1a+ obtained by the photoelectric conversion element 15
Since Ic+ Ib+ Id is proportional to the beam output,
It can also be used to monitor the beam output energy.

The embodiments described above show the case where the present invention is applied to a laser device for ophthalmic treatment, but generally two or more types of output formats are used, for example, pulsed light and continuous light, or if the pulsed light is both pulsed light, the pulse width It goes without saying that the present invention can be applied to various devices that use beams with different timings.

As described above, according to the beam shift detection device according to the present invention,
For example, in a laser device for ophthalmic treatment, the degree of beam deviation between the aiming beam and the main laser beam can be quantitatively and accurately detected, and as a result, it becomes possible to automatically determine the beam deviation. For example, it is possible to monitor and issue a warning for beam deviations caused by changes over time or vibrations received by the device, or to automatically correct beam deviations by electrically adjusting the beam matching mirror or beam matching means. be.

[Brief explanation of the drawing]

The drawings show an embodiment of the beam shift detection device according to the present invention, and FIG. 1 is an optical system layout diagram of the first embodiment, FIG. 2 is a front view of a photoelectric conversion element, and FIG. 3 is an electrical FIG. 4 is a block circuit diagram of the circuit, FIG. 4 is an output waveform diagram, and FIGS. 5 and 6 are diagrams of essential parts of other embodiments. Reference numeral 1 is an objective lens, 2 is an observation optical system, and 8 is a main laser.
, 9 is a sub laser, 10 is a total reflection mirror, 11 is a beam matching means, 12 is a beam expansion optical system, 13 is a filter,
14 is a quick clock mirror, 15 is a photoelectric conversion element, 19
．． 20. 21 is an integral book sample hold circuit, 22 is a timing controller, 23 is a multiplexer, 24 is an A/D conversion circuit, 25 is a CPU, 26 is a display device, 28
The half mirror 129 is a reduction optical system. Patent applicant Canon Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a device that uses two or more beams with different output formats by matching them, a beam position detecting means disposed in the optical path after the beams match, and a position included in the beam position detecting means. A beam shift detection device comprising: an integrating circuit that integrates a photocurrent of a photoelectric conversion element having a detection function; and a control circuit that controls the integration time of the integrating circuit according to different beams. 2. Claim 1, wherein a beam deviation enlarging means is disposed between the beam matching means and the beam position detecting means.
Beam deviation detection device described in . 3. The beam shift detection device according to claim 1, wherein the beam position detection means also serves as beam energy detection means.