JPH07134242A - Focus detector - Google Patents

Abstract

PURPOSE:To put in a laser luminous flux within the effective luminous flux radius of an objective lens even though the effective lumunous flux radius of the lens varies by the kind of the objective lens. CONSTITUTION:When an illumination changeover section 24 is a dark visual field produced by a light shielding cylinder M with a ring mirror and if an objective lens 22 is exchanged, the prism position information corresponding to the lens 22 is taken in from a memory section 45, a control signal is given to a motor driver 47 and a first driving mechanism 40 is operated. The incident luminous flux of the two points detected by a position detection sensor 35 by moving a prism 33 in the direction of the laser optical axis is put in within the effective luminous flux radius of the lens 22. Moreover, when the section 24 is a bright visual field produced by a half mirror HM, the control signal based on the prism position information correspond to the lens 22 is given to a motor drive 4 and a second driving mechanism 44 is operated. The prism 33 is moved in the direction, which is orthogonal to the laser optical axis, so that the incident luminous flux of the two points are moved in parallel and is put within the effective luminous flux radius of the lens 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detecting device capable of adjusting the beam of a microscope, for example, within the effective light velocity diameter of the objective lens even if the beam of the microscope is displaced from the optical axis of the objective lens.

[0002]

2. Description of the Related Art A conventional focus detecting device of this kind, as shown in FIG. 5, causes laser light from laser diodes 1 and 2 to enter a prism 5 through collimator lenses 3 and 4, The reflected light is made incident on the infrared reflection mirror 7 through the polarization beam splitter 6, and the reflected light is further made into a quarter wavelength plate 8
It is incident on the objective lens 9 through. Then, the reflected light from the sample 10 is detected by the position detection sensor (PSD sensor) 11 through the polarization beam splitter 6, and if the objective lens 9 is not in the in-focus position with respect to the sample 10, the control means (not shown) is shown. The objective lens 9 or the sample 10 is controlled in the optical axis direction to move to the in-focus position. The sample is observed by an eyepiece lens 12 provided on the optical axis of the objective lens 9.

[0003]

By the way, in the focus detecting device having such a structure, the laser light flux incident on the objective lens 9 is transmitted from the laser diodes 1 and 2 by the prism 5. Since the light is reflected, it is fixed at a fixed position deviated from the optical axis of the objective lens 9 and deviated from the optical axis determined by the incident and reflected positions of the laser light on the prism 5.

However, since the effective diameter of the pupil of the objective lens 9 varies depending on the type and magnification of the objective lens, as described above, all the laser light flux fixed at a fixed position with respect to the optical axis is used. It was not always possible to effectively enter the objective lens or to receive the detection light effectively. Therefore, when the objective lens 9'having a small effective light beam diameter is exchanged as shown in FIG. 5, a part of the laser light beam protrudes from the effective light beam diameter and a sufficient amount of light cannot be given to the sample. Therefore, there is a problem that the focusing operation becomes unstable.

The present invention has been made in view of the above problems, and the laser light flux can be adjusted within the effective light flux diameter of the objective lens even if the effective light flux diameter of the lens differs depending on the type of the objective lens. An object of the present invention is to provide a focus detection device that can obtain high detection accuracy and detection sensitivity.

[0006]

The present invention takes the following means in order to achieve the above object. (1) Beam light from a light source for focus detection is incident on a prism, and reflected light is projected on a sample through an objective lens that is exchangeably provided in an observation optical system, and from this sample through the objective lens. In a focus detection device that receives incident reflected light by a position detection means and detects the incident position to perform focus determination, the prism or the focus detection light source is adjusted according to the effective light beam diameter of the objective lens. Means is provided for moving the reflected light entering the observation optical system from the prism in a direction orthogonal to the optical axis direction. (2) Beam light from a light source for focus detection is incident on a prism, and reflected light is projected on a sample through an objective lens that is exchangeably provided in an observation optical system, and this sample passes through the objective lens. While receiving the incident reflected light by the position detection means, in the focus detection device for detecting the incident position to perform the focus determination, provided in the observation optical system,
An illumination switching means for switching between darkfield illumination by a light-shielding tube with a ring mirror and brightfield illumination by a half mirror, and a prism or a light source for focus detection from the prism for reflecting light incident on the observation optical system. A first moving means for moving in the optical axis direction, a second moving means for moving the prism or the focus detection light source in a direction orthogonal to the optical axis direction of the reflected light from the prism, and a plurality of different types Storage means for storing the positional information of the prism or the light source for focus detection corresponding to the objective lens, and prism or focus detection corresponding to the objective lens provided in the observation optical system from the storage means when the objective lens is replaced. When the position information of the light source is taken in and the spectroscopic method switching signal input from the illumination switching means is a dark field switching signal, the prism or focus detecting light source The prism or the focus detecting light source is moved by the first moving means based on the position information, and when the spectroscopic method switching signal is a bright field switching signal, based on the position information of the prism or the focus detecting light source. And a control means for moving the prism or the focus detection light source by the second moving means.

[0007]

In the focus detecting device having the structure as described in the above (1), even if the beam of light beam generated by the refraction of the lens of the illumination system during bright field illumination is out of the effective beam diameter of the objective lens. By moving the prism or the light source for focus detection in the direction orthogonal to the optical axis direction of the reflected light that enters the observation optical system from the prism, the light beam beam can be adjusted to the effective light beam diameter of the objective lens.

Further, in the focus detecting device having the above-mentioned constitution (1), when the objective lens is replaced when the illumination switching means is in the dark field, the prism corresponding to the objective lens or the focus detecting light source. Position information from the storage means and the control means operates the first moving means to move the prism or the focus detection light source in the optical axis direction of the reflected light entering the observation optical system from the prism, and the position detection means The incident light beam detected by the above is put within the effective light beam diameter of the objective lens, and when the illumination switching means is in the bright field, the control means operates the second moving means to observe the prism or the focus detection light source from the prism. It is possible to move the incident light beam in a direction orthogonal to the optical axis direction of the reflected light entering the lens and enter it within the effective light beam diameter of the objective lens.

Therefore, the incident light flux detected by the position detecting means can be included in the effective light flux of the objective lens in both the dark field and the bright field, so that the beam position is set to match the objective lens. it can. As a result, even if the effective light beam diameter of the lens varies depending on the type of the objective lens, the incident light beam does not protrude, and high detection accuracy and detection sensitivity can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a first embodiment of a focus detection device according to the present invention. In FIG. 1, 21 is a revolver in which a plurality of objective lenses 22 having different effective light beam diameters of the lenses are set, 23 is a quarter-wave plate provided on the optical axis of the objective lenses 22, and 24 is a light source for illumination 25. 2 and the speculum method is bright field.
In M, an illumination switching unit that switches to the light-shielding cylinder M with a ring mirror in the dark field, 26 is an infrared reflection mirror, and 27 is an eyepiece 28 for a sample image transmitted through this infrared reflection mirror 26.
This is a TV camera that captures images via.

On the other hand, reference numerals 29 and 30 are rays which emit infrared light.
The diode, 31 and 32 are collimator lenses, and 33 is laser diode 29 and 30 from collimator 31, 32
The prism that reflects the infrared light incident through the polarization beam splitter 34 and enters the infrared reflection mirror 26 through the polarization beam splitter 34 is a position where the reflected light from the sample 36 is received through the polarization beam splitter 34. The position detection signal detected by the position detection sensor 35 is detected by a detection sensor (PSD sensor) by a control means (not shown) to determine whether or not the objective lens 22 is at the in-focus position with respect to the sample 36, and the in-focus position is determined. Otherwise, the objective lens 22 or the sample 36 is controlled in the optical axis direction.

In the focal position detecting device having such a structure, in the first embodiment, the pinion 38 rotated by the servo motor 37 and the rotation of the pinion 38 cause the prism 33 to move the prism 33 in the laser optical axis direction (X direction). ) Is provided with a first drive mechanism 40 having a rack 39 for advancing and retreating, and the pinion 42 rotated by the servomotor 41 and the rotation of this pinion 42 make the prism 33 orthogonal to the laser optical axis direction. A second drive mechanism 44 having a rack 43 that moves in the direction (Z direction) is provided.

On the other hand, the memory section 45 in which the positional information of the prism 33 is stored corresponding to the type of the objective lens 22 set in the revolver 21, and the hole position of the revolver 21 in which the objective lens 22 is set are in the optical path. When the position information is input, the position information of the prism corresponding to the objective lens is fetched from the memory unit 24, and the illumination switching unit 2
When a microscopic method switching signal is input from 4, control is performed to determine whether the microscopic method switching signal is a dark field switching signal or a bright field switching signal and output a control signal according to prism position information. And a motor driver 47 for operating the first drive mechanism 40 or the second drive mechanism 44 based on a control signal input from the control unit 46. In this case, the motor driver 47 operates the first drive mechanism 40 when the control unit 46 determines that the microscopic method switching signal is the dark field switching signal, and also determines that it is the bright field switching signal. And the second drive mechanism 44 is operated.

Next, the operation of the focus detection device configured as described above will be described. Now, when the illumination switching section 24 is in the dark field illumination state, when infrared light is emitted from the laser diodes 29 and 30, this infrared light is reflected by the prism 33 and is polarized by the polarization beam splitter 34. Then, the light is incident on the observation optical system by the infrared reflection mirror 26.

The laser light incident on this observation optical system passes through a light-shielding cylinder M with a ring mirror as shown in FIG.
When entering the 4λ wavelength plate 23, the 1 / 4λ phase is rotated here and the light enters the objective lens 22. The infrared light reflected from the sample 36 is reflected by the objective lens 22 and the infrared reflection mirror-2.
After passing through 6, the beam passes through the polarization beam splitter 34 and is detected by the position detection sensor 35. At this time, it is assumed that the two incident light beams are included in the effective light beam of the objective lens 22 as shown in (a) of FIG.

When the objective lens 22 having a large pupil diameter is exchanged from such a state, the distance between the two incident light fluxes is expanded from L1 to L2, and a part of the incident light flux is (b) in FIG. 3 (a).
As shown in FIG. At this time, when the objective lens 22 selected by the rotation of the revolver 21 enters the optical path, its position information is obtained by the control unit 4.
6 is input. Then, the control unit 46 controls the memory unit 4
The position information of the prism corresponding to the objective lens is fetched from 5 and input to the motor driver 47. In this case, since the dark field switching signal is input to the control unit 46 as the spectroscopic method switching signal, the motor driver 47 causes the first drive mechanism 4 to operate.
0 is operated based on the control signal according to the prism position information input from the control unit 46.

That is, in the first drive mechanism 40, the servo
When the motor 37 rotates based on the prism position information,
The rack 39 retracts in the laser beam axial direction (X direction) by the pinion 38, and the prism 33 moves.

Therefore, the position of the infrared light reflecting surface is changed by the movement of the prism 33, and the optical axes of the lasers are moved toward each other, so that the two incident light beams detected by the position detection sensor 35 are detected. The distance between them narrows from L2 to L1,
As shown in (c) of FIG. 3 (a), it is possible to enter a laser beam suitable for the objective lens 22 into the effective light flux of the objective lens 22.

Next, the operation when the dark field is switched to the bright field as the spectroscopic method will be described. Now, the lighting switching unit 24
2 shows a light-shielding cylinder M with a ring mirror shown in FIG.
2 is switched to the half mirror HM shown in FIG. 2A, the bright field switching signal is input to the control section 46 from the dark field switching signal as the spectroscopic method switching signal. In this case, when the Hahmir HM is inserted in the inspection optical system, the laser light is
As shown in (a), the optical axis is deviated by α between the entrance and the exit of the half mirror HM due to the refraction by the thickness t of the half mirror.

Therefore, in the state where the microscope is performed in the bright field, the incident light beams at the two points are included in the effective light beam of the objective lens 22 as shown in FIG. When switching from the visual field to the bright field, the incident light flux at two points is shown in FIG. 3 (b).
As shown in (b) of (2), the light beam is moved in parallel by the amount of refraction by the Hough mirror HM, and a part of the incident light beam at the right side point in the figure is located outside the effective light beam of the objective lens.

At this time, since the position information of the objective lens 22 in the optical path and the bright-field switching signal as the microscopic method switching signal are input to the control section 46, the motor driver 47 drives the second drive. The mechanism 44 is operated based on the control signal according to the prism position information input from the control unit 46.

That is, in the second drive mechanism 44,
When the motor 41 rotates based on the prism position information,
The pinion 42 moves the rack 43 downward in the direction orthogonal to the laser beam axis, here, downward, and the prism 33 descends.

Therefore, by moving the prism 33,
Since the distance L1 between the incident light beams at the points is kept constant, the incident light beams at the two points detected by the position detection sensor 35 are the objective lens 22 as shown in (c) of FIG. It is possible to enter a laser beam suitable for the objective lens 22 into the effective luminous flux of

As described above, in the first embodiment, when the illumination switching unit 24 is the dark field by the light blocking cylinder M with the ring mirror,
When the objective lens 22 is replaced, the prism position information corresponding to the objective lens 22 is fetched from the memory unit 45 and the mode is read.
A drive signal to the first drive mechanism 40
Is operated to move the prism 33 in the laser optical axis direction so that the two incident light beams detected by the position detection sensor 35 are placed within the effective light beam diameter of the objective lens 22, and the illumination switching unit 24
In the case of a bright field by Hough Miller HM, a control signal corresponding to the prism position information corresponding to the objective lens 22 is given to the motor drive 4 to operate the second drive mechanism 44 to move the prism 33. -The incident light flux at two points is moved in parallel in the direction orthogonal to the optical axis so as to enter the effective light flux diameter of the objective lens 22.

Therefore, even in the case of the dark field by the light-shielding cylinder M with the ring mirror and the bright field by the half mirror HM, the two incident light beams detected by the position detection sensor 35 are included in the effective light beam of the objective lens 22. Laser light suitable for the objective lens 22 can be made incident. As a result, even if the effective diameter of the lens varies depending on the type of objective lens, the incident light flux does not protrude,
High detection accuracy and detection sensitivity can be obtained.

In the first embodiment, the prism 33 is moved in the laser optical axis direction by the first driving mechanism 40, and is moved in the direction orthogonal to the laser optical axis by the second driving mechanism 44. Although the case has been described, the case including the laser diodes 29, 30 and the collimator lenses 31, 32 as in the second embodiment shown in FIG.
Even if it is moved in the same manner as described above by the 0, 2nd drive mechanism 44, the same effect as in the above embodiment can be obtained. In this case, the memory section 45 has a laser diode 2
A case containing 9, 30 and collimator lenses 31, 32
It goes without saying that the positional information of the scanning line is stored in association with the objective lens. In addition to the above, the present invention can be variously modified and implemented within the scope of the invention.

[0027]

As described above, according to the present invention, even if the effective light beam diameter of the lens differs depending on the type of the objective lens, the laser light beam can be matched within the effective light beam diameter of the objective lens, and high detection is possible. It is possible to provide a focus detection device capable of obtaining accuracy and detection sensitivity.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a focus detection device according to the present invention.

FIG. 2 is a diagram showing a light-shielding cylinder with a half mirror and a ring mirror that can be switched by an illumination switching unit in the embodiment.

FIG. 3 is a diagram for explaining an operation when the laser light flux is adjusted within the effective light flux diameter of the objective lens in the embodiment.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing an example of a conventional focus detection device.

[Explanation of symbols]

21 ... Revolver, 22 ... Objective lens, 23 ... 1 / 4λ
Wave plate, 24 ... Illumination switching section, 25 ... Light source, 26 ... Infrared reflection mirror, 27 ... TV camera, 28 ... Eyepiece, 2
9, 30 ... Laser diode, 31, 32 ... Collimator lens, 33 ... Prism, 34 ... Polarization beam splitter, 35 ... Position detection sensor, 36 ... Specimen, 40 ... First drive mechanism, 44 ... Second drive mechanism, 45 ... Memory section, 4
6 ... Control unit, 47 ... Motor driver.

Claims (3)

[Claims] 1. Beam light from a focus detection light source is incident on a prism, and reflected light is projected onto a sample through an objective lens that is exchangeably provided in an observation optical system. In a focus detection device that receives reflected light incident through the position detection means and detects the incident position to perform focus determination, the prism or the focus detection light source is adjusted to the effective light beam diameter of the objective lens. A focus detecting device, comprising means for moving the reflected light from the prism in a direction orthogonal to the optical axis direction of the reflected light incident on the observation optical system. 2. Beam light from a light source for focus detection is incident on a prism, and the reflected light is projected onto a sample through an objective lens that is exchangeably provided in an observation optical system. In a focus detection device that receives reflected light incident through the position detection means and detects the incident position to perform focus determination, the prism or the focus detection light source is incident on the observation optical system from the prism. First moving means for moving in the optical axis direction of the reflected light, and second moving means for moving the prism or the focus detection light source in a direction orthogonal to the optical axis direction of the reflected light from the prism, Storage means for storing the positional information of the prism or the light source for focus detection corresponding to a plurality of objective lenses of different types, and an observation optical system from the storage means when the objective lens is replaced. Control means for taking in the position information of the prism or the focus detection light source corresponding to the objective lens to be moved, and for moving the prism or the focus detection light source by the first moving means or the second moving means based on this position information A focus detection apparatus comprising: 3. Beam light from a focus detection light source is incident on a prism, and the reflected light is projected onto a sample through an objective lens that is exchangeably provided in an observation optical system. In a focus detection device that receives reflected light incident through the position detection means and detects the incident position to perform focus determination, dark field illumination by a light-shielding tube with a ring mirror provided in the observation optical system. And an illumination switching means for switching the brightfield illumination by the half mirror, and a first light source for moving the prism or the focus detection light source in the optical axis direction of the reflected light incident on the observation optical system from the prism. Moving means, second moving means for moving the prism or the focus detection light source in a direction orthogonal to the optical axis direction of the reflected light from the prism, and a plurality of objectives of different types Of the prism or the focus detection light source corresponding to the objective lens provided in the observation optical system from the storage means when the objective lens is replaced. When the position information is taken in and the microscopic method switching signal input from the illumination switching means is a dark field switching signal, the prism or the prism is moved by the first moving means based on the position information of the prism or the focus detection light source. The focus detecting light source is moved, and when the microscopic method switching signal is the bright field switching signal, the second moving means moves the prism or the focus detecting light source based on the position information of the prism or the focus detecting light source. A focus detection apparatus comprising: a control unit that moves the focus detection apparatus.