JPS61219022A - Aiming device - Google Patents

Abstract

PURPOSE:To obtain a high-accuracy aiming device which has no movable part and simple structure by providing a light-crystal plate which plural liquid-crystal elements arranged on an aiming optical path and driving device which drives the respective liquid-crystal elements successively and varies drive condition, and varying the drive condition and adjusting the transmissivity of the liquid- crystal elements. CONSTITUTION:Visible aiming light projected from an aiming light source 5 is made into two pieces of luminous flux through the liquid-crystal plate 6, and the respective pieces of luminous flux are converged through a condenser lens 7 and passed through a light splitting member 4 to form an image on an object body P. The liquid-crystal plate 6 has two liquid-crystal elements 6a and 6b and an transparent electrode is provided on both surface; when TN type liquid-drystal is used, a polarizing plate which is equalized in polarization direction is arranged on both surfaces. The liquid-crystal driving device 8 varies the drive condition of the respective liquid-crystal elements to vary the transmissivity of the liquid-crystal, so the quantity of aiming light is increased or decreased properly according to the reflectivity of the object P.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention is applicable to, for example, a YAG laser device for ophthalmic treatment, a processing laser device, etc., in order to previously align the point of action of the laser, adjust the focus, etc. This invention relates to the aiming device used.

[Prior Art] Lasers have extremely excellent focusing and directivity, and in recent years, infrared lasers, pulsed lasers, and the like have been used in a wide range of fields. However, when an infrared laser is used, since the laser light is infrared light, it cannot be visually recognized, and it is impossible to position the point of action or adjust the focus. Furthermore, in the case of a pulsed laser, there are drawbacks such as difficulty in aiming due to the pulsed light emission. Furthermore, when performing treatment, processing, etc. using a laser, a laser with an energy that matches the purpose is irradiated, but if it is irradiated to an unnecessary location, that location will be destroyed. Therefore, in consideration of safety, it is desirable to install an aiming light source using a visible light source separately from the working light source.
It is necessary to align the point of action and adjust the focus. As the aiming light source, a laser light source is used like the single-action light source because accurate positioning is required, but a visible light continuous wave laser light source is used to enable aiming. A He-Me laser is generally used as the aiming light source, and the oscillation output is determined with safety in mind.

In such aiming devices, from the standpoint of safety, it is necessary to adjust the light intensity to the minimum necessary according to the reflectance of the object to be irradiated with the laser, and conventionally, filters with different densities are placed in the aiming light path. Insert it to adjust the light intensity. In particular, in the aiming device of a laser device for eye treatment, the energy density of the irradiated laser is extremely high due to the optical system inside the eye, making it even more dangerous than in other living organisms, so it is necessary to carefully adjust the light intensity. There is.

In addition, when aiming, laser light is emitted from multiple positions, and focus adjustment is performed depending on whether the imaging points match or not.If laser light is emitted from multiple positions at the same time, the focus may shift considerably. In some cases, a plurality of clearly different irradiation spots can be obtained, and a focus shift can be detected. When the focus is almost perfect, although imperfect, a plurality of light beams may interfere with each other, making it difficult to distinguish whether they are at one point or at multiple points. for that.

Rather than emitting light sequentially from multiple apertures installed in the aiming optical path and comparing the positions of multiple spots at the same time, the movement of multiple spot positions is detected and the aiming completion point is the point at which there is no more movement. A method of determining this is adopted. To this end, conventional methods have been used, such as using a chopper to sequentially emit light from a plurality of apertures installed in the aiming optical path. In this way, conventional devices have drawbacks such as the need to take in and out filters and choppers, which require mechanically moving parts, making the structure complex, high cost, and prone to failure. ing.

[Object of the Invention] An object of the present invention is to improve the drawbacks of the above-mentioned conventional examples and to provide an aiming device that has no moving parts, is structurally simple, and has high accuracy.

[Summary of the invention] The gist of the present invention is to achieve the above objects.

A liquid crystal plate disposed in an aiming optical path and having a plurality of liquid crystal elements, and a drive device that sequentially drives each of the liquid crystal elements and varies driving conditions, and by changing the driving conditions, the liquid crystal elements can be controlled. This is an aiming device characterized by adjusting the transmittance of the.

[Embodiments of the invention] 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. A light lens 3 and a light splitting member 4 are arranged in sequence so that the subject P is located on the optical axis 02 of the light beam reflected by the light splitting member 4. As an aiming device, an aiming light source 5 and a liquid crystal plate 6 are provided on an optical axis 02 passing through a light splitting member 4, and a condenser lens 7 is further arranged at a position conjugate with the condenser lens 3. A liquid crystal driving device 8 is connected to the liquid crystal plate 6 and is capable of applying a voltage and changing driving conditions such as the applied voltage or driving frequency.

The visible aiming light emitted from the aiming light source 5 is
Two light beams are formed through the liquid crystal plate 6, and each light beam is condensed by a condenser lens 7, and an image is formed on the subject P through the light splitting member 4. After completing positioning of the point of action and focus adjustment using the aiming device, the light emitted from the action light source 1 such as an infrared laser is expanded by the beam expander 2, further condensed by the condensing lens 3, The light is reflected by the light splitting member 4 and focused onto the subject P.

Since the condensing lens 7 and the condensing lens 3 are arranged conjugately, it is possible to move the entire apparatus relative to the subject P or to simultaneously move the condensing lens 3.7 on the optical axis 01.02. If the aiming device can perform the positioning and focus adjustment of the point of action, then the positioning and focus adjustment of the point of action have been completed in the therapeutic laser device as well.

FIG. 2 is a front view of the liquid crystal plate 6 viewed from the optical axis 02 direction, and in this example, the liquid crystal plate 6 has two liquid crystal elements 6a and 6b. Transparent electrodes are provided on both sides of the regions of these elements 6a and 6b so that a voltage can be applied by the liquid crystal driving device 8. Note that the liquid crystal element 6 of the liquid crystal plate 6
a, 6b may be 3 (11 or more) instead of 2.

When using a TN type liquid crystal, polarizing plates with the same polarization direction are arranged on one both sides. In this case, when no voltage is applied to the liquid crystal elements 6a and 6b, the element 6a
, 6b, the molecular orientations are perpendicular to each other, so the light that passes through one polarizing plate and passes through the elements 6a and 6b is polarized in a direction perpendicular to the direction of incidence, and the other polarized light is Light cannot pass through the plate because it cannot pass through the plate, but when a voltage is applied, the orientation of the molecules changes, and the optical rotation of the liquid crystal disappears, allowing light to pass through. Therefore, by gradually lowering the applied voltage using the liquid crystal driving device 8, the transmittance of the liquid crystal can be continuously decreased, and by gradually increasing the applied voltage, the transmittance of the liquid crystal can be continuously decreased. can be made larger. Furthermore, instead of changing the applied voltage, the transmittance can be similarly changed by changing the driving frequency.

In addition, in the case of the example, the polarization direction of the polarizing plates arranged on both sides of the liquid crystal was set to be the same direction, but if these are arranged in orthogonal directions, contrary to the example, when no voltage is applied, the light is emitted. When a voltage is applied, no light is transmitted. Even in this case, the same effect as in the embodiment can be obtained, so it is only necessary to adopt the one that is easier to operate depending on the device.In this way, the transmittance of the liquid crystal can be varied by changing the driving conditions of each liquid crystal element. Because you can.

It becomes possible to appropriately increase or decrease the amount of aiming light in accordance with the reflectance of the subject P.

Note that when using a GH type liquid crystal in which dye molecules having remarkable dichroism are added and their interaction can be utilized, the above-mentioned polarizing plate may not be used.

Figures 3 (a) and (b) illustrate the spot of the aiming light on the subject P, where (a) is out of focus, (11) is in focus, and the spot SO is one point. are gathering.

When the focus is out of focus, the aiming light is divided into two spots sa and sb as shown in Ca). At this time, if the liquid crystal elements 6a and 6b are sequentially driven, blurring of the spot due to slight deviation can be recognized, it is possible to clearly confirm whether aiming is completed, and highly accurate adjustment can be easily performed. I can do it.

[Effects of the Invention] As explained above, the aiming device according to the present invention can easily adjust the amount of aiming light by changing the driving conditions such as the voltage and frequency for driving the liquid crystal element, and can easily adjust the amount of aiming light. Sequential illumination of the light beam enables highly accurate focus adjustment. Furthermore, since there is no mechanical drive unit, the structure is extremely simple, which contributes to cost reduction, size reduction, etc.

[Brief explanation of drawings]

The drawings show an embodiment of the aiming device according to the present invention; FIG. 1 is a diagram of the overall configuration, FIG. 2 is a front view of the liquid crystal plate, and FIGS. 3(a) and (b) are views of the object to be examined. It is an explanatory view of the spot of the aiming light on P. Reference numeral 1 indicates an active light source, 2 indicates a beam expander, 3.7 indicates a condensing lens, 4 indicates a light splitting member, 5 indicates an aiming light source, and 6 indicates
1 is a liquid crystal plate, 6a and 6b are liquid crystal elements, and 8 is a liquid crystal driving device. Patent applicant Canon Co., Ltd. Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. A liquid crystal plate disposed in an aiming optical path and having a plurality of liquid crystal elements, and a driving device for sequentially driving each of the liquid crystal elements and varying driving conditions, An aiming device characterized in that the transmittance of the liquid crystal element is adjusted by changing conditions. 2. The aiming device according to claim 1, wherein the aiming light source that illuminates the liquid crystal plate is a laser light source that continuously oscillates visible light. 3. The aiming device according to claim 1, wherein the liquid crystal plate is a TN type liquid crystal with a transparent electrode coating applied to the plurality of element regions, and polarizing plates are arranged on both sides of the TN type liquid crystal. 4. The aiming device according to claim 1, wherein the liquid crystal plate is a GH type liquid crystal in which a transparent electrode coating is applied to the plurality of element regions. 5. The aiming device according to claim 1, wherein the driving device is configured to vary a voltage or a driving frequency.