JP2008268054A - Device for measuring focal position - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure the focal position of a measured optical system, even if temperature change occurs in a measuring atmosphere, in a device for measuring focal position. <P>SOLUTION: The device 100 for measuring the focal position includes a work stage 2 for holding an objective lens to be inspected 1; a light source part for making measuring light incident on the objective lens to be inspected 1; a specimen mirror 6 for reflecting the measuring light transmitting the objective lens to be inspected 1; a moving mechanism 7 for moving the specimen mirror 6 along an optical axis; a collimator lens 5 for imaging light incident on the objective lens to be inspected 1 again; a pinhole 9 and a light-receiving element 10 for detecting the imaging position of light due to the collimator lens 5; a laser length measuring machine 11 for detecting a moving amount of the specimen mirror 6; and a temperature sensor 12 for detecting the atmospheric temperature surrounding the objective lens to be inspected 1 held on the work stage 2. A warning promoting resetting of a measurement original point is displayed, in response to the temperature sensor 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a focal position measurement apparatus. For example, the present invention relates to a focal position measuring apparatus using a microscope objective lens or the like as an optical system to be measured.

Conventionally, for example, in a manufacturing process of an objective lens unit or the like, a focal length measurement or a focal position measurement from a reference position (hereinafter referred to as a focal position measurement including both) is performed after the unit is assembled.
For example, in Patent Document 1, as such a focus position measuring device, a divergent light beam generating means for a measurement-supported optical system that is movably supported, an optical support that supports the measurement-target optical system movably, A focal length measuring device for an optical system comprising a divergent beam generating means for detecting a light beam convergence point and a position of the measured optical system, comprising a peripheral speed point detecting means for the emitted light beam from the measured optical system Is described.
Further, in the conventional technique of Patent Document 1, a device configuration using a nodal slide method and a magnification method is described as a focal position measurement device using a parallel light beam.
JP-A-7-55638

However, the conventional focus position measuring apparatus as described above has the following problems.
In all of the techniques described in Patent Document 1, the distance along the optical axis is measured to determine the focal length and the focal position. Therefore, when a temperature change occurs in the measurement environment, there is a problem that distance measurement becomes inaccurate and the measurement accuracy of the focal position is lowered.
Although it is conceivable to control the temperature of the measurement environment to a constant temperature, in the focal position measurement in the manufacturing process, the finished product produced one after another is used as the measured optical system one after another, so the measured optical system is frequently replaced. It will be. For this reason, it is difficult to accurately maintain the measurement environment at a constant temperature. If the optical system to be measured is replaced until it reaches a temperature equilibrium state, there is a problem that the measurement efficiency is remarkably deteriorated.

  The present invention has been made in view of the above problems, and provides a focal position measuring apparatus capable of accurately measuring a focal position of an optical system to be measured even when a temperature change occurs in a measurement atmosphere. For the purpose.

In order to solve the above-described problem, in the invention described in claim 1, the focus position for measuring the focus position from the reference position by making the measurement light incident on the optical system to be measured and detecting the imaging position. A measuring apparatus, a measured optical system holding unit that holds the measured optical system at the reference position, a light source unit that allows a parallel light beam to enter the measured optical system as measurement light, and the measured optical A reflection mirror for reflecting the measurement light transmitted through the system in the direction of the optical axis, a moving mechanism for moving the reflection mirror along the optical axis, and the measurement optical system re-entered the optical system to be measured via the reflection mirror An imaging lens that images light, an imaging position detection mechanism that detects an imaging position of light that has passed through the imaging lens, and a movement that detects the amount of movement of a reflecting mirror that is supported by the moving mechanism and moves Held by the quantity detection mechanism and the optical system holder to be measured. Wherein a temperature sensor for detecting the ambient temperature around the measurement optical system, in accordance with the detected temperature of the temperature sensor, a configuration in which to perform a warning display to prompt resetting of the measurement origin.
According to this invention, a parallel light beam is incident as measurement light from the light source unit on the measured optical system held at the reference position by the measured optical system holding unit, and the light transmitted through the measured optical system is transmitted. The light is reflected by a reflection mirror, the reflected light is incident again on the optical system to be measured, and the transmitted light is imaged by an imaging lens. Then, the imaging position of the imaging lens is changed by moving the reflection mirror in the optical axis direction by the moving mechanism. Then, this imaging position is detected by an imaging position detection mechanism, and the position of the reflection mirror is adjusted so that a predetermined imaging position is obtained. The focal position of the optical system to be measured with respect to the reference position can be measured by detecting the movement position of the reflecting mirror after adjustment by the movement amount detection mechanism.
At that time, the temperature sensor detects the ambient temperature around the measured optical system held by the measured optical system holding part, and a warning display prompts the user to reset the measurement origin according to the detected temperature of the temperature sensor. Is done.
Thereby, when the amount of temperature change becomes a size that cannot satisfy the predetermined measurement accuracy, it is possible to maintain good measurement accuracy by resetting the measurement origin.

According to a second aspect of the present invention, in the focal position measurement device according to the first aspect, the movement amount detected by the movement amount detection mechanism is corrected according to the detection output of the temperature sensor. .
According to this invention, since the movement amount of the movement amount detection mechanism is corrected according to the detection output of the temperature sensor, it is possible to detect an accurate movement amount according to the ambient temperature around the optical system to be measured.

According to a third aspect of the present invention, in the focal position measuring apparatus according to the first or second aspect, the measured optical system holding unit supports the measured optical system at three points.
According to this invention, since the measured optical system holding unit supports the measured optical system at three points, it is possible to improve the positioning accuracy of the measured optical system with respect to the reference position, and the measured optical system holding unit Therefore, the temperature change of the measurement environment accompanying the replacement of the optical system to be measured can be reduced.

  According to the focal position measuring apparatus of the present invention, the ambient temperature in the focal position measurement is detected by the temperature sensor, and a warning display prompting the resetting of the measurement origin is performed according to the detected temperature, so that the temperature change of the measured atmosphere is detected. Even if it occurs, it is possible to accurately measure the focal position of the optical system to be measured by resetting the measurement origin.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
A focal position measurement apparatus according to an embodiment of the present invention will be described.
FIG. 1 is a schematic front view showing a schematic configuration of a focal position measuring apparatus according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a measured optical system and a measured optical system holding unit of the focal position measuring apparatus according to the embodiment of the present invention. FIG. 3 is a control block diagram of the focal position measuring apparatus according to the embodiment of the present invention.

As shown in FIG. 1, the schematic configuration of the focal position measuring apparatus 100 of the present embodiment includes an apparatus main body 18 in which a laser light source 3, a half mirror 8, a mirror 4, and a collimating lens 5 (imaging lens) are housed, A work stage 2 (measurement optical system holder) fixed to a top plate 18a constituting the upper surface of the apparatus body 18, and a sample mirror 6 (reflection mirror) provided so as to be movable in the vertical direction above the top plate 18a. The laser measuring machine 11 (movement amount detection mechanism) that measures the movement position of the sample mirror 6, the temperature sensor 12, the light receiving element 10, and the control unit 14 that controls the operation of these components.
With such a configuration, the focal position of the optical system to be measured arranged on the work stage 2 can be measured.
Below, as an example of the optical system to be measured, an example in the case of measuring the focal position of the objective lens 1 as shown in FIG. 2 will be described.

The objective lens 1 to be tested is a lens unit in which a plurality of lenses such as lenses L1, L2, and L3 are arranged inside a substantially cylindrical lens barrel 1a to constitute an objective optical system of infinity design. . The optical axis P of the objective lens 1 to be examined is coincident with the central axis of the lens barrel 1a.
At one end side of the lens barrel 1a, for example, an attachment portion 1c for mounting on a microscope or the like and an attachment reference surface 1b made of a plane orthogonal to the optical axis P for positioning in the optical axis P direction at the time of attachment. Is formed.
In the present embodiment, the attachment portion 1c is formed by a male screw having an outer diameter slightly smaller than the outer diameter of the lens barrel 1a.
The attachment reference surface 1b is an annular flat surface extending from the outer peripheral portion of the attachment portion 1c to the outer shape portion of the lens barrel 1a.

  In the present embodiment, the work stage 2 is made of a glass plate having a smooth surface, and includes a measurement reference surface 2a (reference position) for supporting the attachment reference surface 1b of the objective lens 1 to be measured on the upper surface side. At the center of the measurement reference surface 2a, a guide hole 2b penetrating in the thickness direction with an inner diameter slightly larger than the mounting portion 1c of the objective lens 1 to be examined is provided. For this reason, when the mounting reference surface 1b is set on the measurement reference surface 2a in a state where the mounting portion 1c of the objective lens 1 to be tested is housed in the guide hole 2b, the optical axis P is positioned substantially at the center of the guide hole 2b. .

The laser light source 3 generates measurement light incident on the objective lens 1 as divergent light. For example, it is composed of a semiconductor laser having an appropriate wavelength.
The half mirror 8 is an optical path branching unit that branches an optical path between the laser light source 3 and the objective lens 1 to be examined.
The mirror 4 reflects the measurement light transmitted through the half mirror 8 and bends the optical path so as to be orthogonal to the measurement reference plane 2a and to pass through the center of the measurement reference plane 2a.

The collimating lens 5 is an optical element that is provided on the optical path between the mirror 4 and the work stage 2 and condenses the measurement light reflected by the mirror 4 into a parallel light beam.
For this reason, the laser light source 3, the half mirror 8, the mirror 4, and the collimating lens 5 constitute a light source unit that causes a parallel light beam to enter the objective lens 1 to be examined.
The focal length of the collimating lens 5 is set to a value that is sufficiently longer than the focal length of the objective lens 1 to be tested, for example, about several hundred mm so that the collimating lens 5 is less susceptible to temperature changes.

The sample mirror 6 is a plane mirror orthogonal to the optical axis of the measurement light so that the measurement light transmitted through the guide hole 2b and collected by the objective lens 1 can be folded back onto the optical axis. It has become.
The specimen mirror 6 is vertically moved along the optical axis by a moving mechanism 7 provided so as to be movable along the optical axis of the measurement light on a column portion 13 made of low thermal expansion metal, e.g. It is supported to be movable in the direction.
The moving mechanism 7 supports the sample mirror 6 so as to be movable in the vertical direction along the optical axis within a predetermined distance range above the measurement reference surface 2a of the work stage 2. For example, a single-axis stage driven by a ball screw, An appropriate mechanism such as a drive mechanism using a linear motor or a piezoelectric element can be employed.

  The laser length measuring machine 11 is fixed to the upper part of the support column 13 and measures the moving position of the sample mirror 6 in the vertical direction. The measurement result of the laser length measuring instrument 11 is sent to the control unit 14 and can be used as calculation data for calculating the focal position and data for movement control of the moving mechanism 7.

  The temperature sensor 12 is a sensor that measures the ambient temperature around the objective lens 1 supported by the work stage 2. The detected temperature data detected by the temperature sensor 12 is sent to the control unit 14.

The light receiving element 10 reflects the measurement light reflected by the sample mirror 6, collected by the test objective lens 1 and the collimating lens 5, and reflected by the mirror 4 and the half mirror 8 from the focal position of the collimating lens 5 on the image side. For detecting the imaging position of the measurement light by the change in the amount of light. For example, it is composed of a photodiode, a CCD, or the like.
On the optical path between the half mirror 8 and the light receiving element 10, a pinhole 9 that restricts incident light to the light receiving element 10 is disposed at a position corresponding to the focal position of the collimating lens 5. That is, the pinhole 9 is disposed at a confocal position with respect to the laser light source 3.
For this reason, in this embodiment, the collimating lens 5 also serves as an imaging lens that forms an image of light re-entered into the optical system to be measured via the reflection mirror, and the pinhole 9 and the light receiving element 10 are connected to each other. An image forming position detecting mechanism for detecting the image forming position of the light transmitted through the image lens is configured.

As shown in FIG. 3, the control unit 14 is electrically connected to the moving mechanism 7, the laser length measuring device 11, the temperature sensor 12, the display unit 14 a, and the light receiving element 10, and communicates with each other to control operation. Data acquisition, data calculation, etc. can be performed.
As a device configuration of the control unit 14, various types of computers are configured by executing programs created corresponding to various control functions and arithmetic functions using a computer including a CPU, a memory, an input / output unit, an external storage device, and the like. The control function and calculation function are realized.
Control performed by the control unit 14 includes movement control of the movement mechanism 7, and includes zero reset control described later. Further, the position information and the detected temperature of the sample mirror 6 can be acquired from the laser length measuring machine 11 and the temperature sensor 12, respectively. From the light receiving element 10, the amount of received light corresponding to the moving position of the sample mirror 6 is acquired, and the received light amount is compared and calculated so that the maximum value of the received light amount can be detected.

The display unit 14a can switch and display an appropriate operation screen, measurement result display screen, message screen, and the like, and includes, for example, a monitor or a liquid crystal panel.
In the present embodiment, when the detected temperature of the temperature sensor 12 exceeds a certain temperature range, a warning display that prompts the user to reset the measurement origin can be displayed on the message screen.
The constant temperature range can be appropriately set according to the need for measurement accuracy, taking into account, for example, fluctuations in the fixed position of the laser length measuring instrument 11 due to thermal expansion of the support column 13. For example, in the case of the test objective lens 1 having a focal position of 45 mm, the length measurement accuracy is preferably about 0.5 μm or less. For this reason, in the present embodiment, a warning display is set when the temperature changes by 1 ° C. or more from the temperature at which the zero reset operation described later is performed.

Next, the operation of the focal position measurement apparatus 100 will be described.
FIG. 4 is a schematic diagram for explaining the zero reset operation and the reference jig measurement operation of the focal position measurement apparatus according to the embodiment of the present invention.

In the focus position measuring apparatus 100, the ambient temperature is detected by the temperature sensor 12 when the power is turned on, and the temperature detection is repeated at a constant sampling cycle.
In the focal position measuring apparatus 100, the zero reset process, the reference jig measuring process, and the focal position measuring process are sequentially performed.

  First, in the zero reset process, as indicated by a broken line in FIG. 4, the sample mirror 6 is lowered in a state where nothing is arranged on the work stage 2, and the sample mirror 6 is brought into contact with the measurement reference plane 2a. Then, the position (upper surface position) of the sample mirror 6 at this time is measured by the laser length measuring machine 11, and the upper surface position of the sample mirror 6 is set as the measurement origin. At this time, the temperature detected by the temperature sensor 12 is stored in the control unit 14 as a reference temperature.

Next, in the reference jig measuring step, as shown by the solid line in FIG. 4, a reference jig 15 whose length is known in advance is placed on the measurement reference surface 2 a and the sample mirror 6 is placed on the upper surface of the reference jig 15. Make contact. At this time, the upper surface position of the sample mirror 6 is measured by the laser length measuring machine 11.
Here, the reference jig 15 is made of a material that has a small coefficient of thermal expansion and is unlikely to be scratched on the surface. In this embodiment, Zerodur (registered trademark) having a thermal expansion coefficient of 0 ± 0.1 × 10 ⁻⁶ / ° C. is used.

The control unit 14 compares the measurement result of the laser length measuring machine 11 with the length of the reference jig 15 stored in advance, and if the difference is within an allowable range, the reference jig measurement process is completed, and the focal position is determined. Move on to the measurement process.
On the other hand, when the difference between the measurement result of the laser length measuring instrument 11 and the length of the reference jig 15 stored in advance exceeds the allowable range, the operation of the zero reset process or the reference jig measurement process is not performed correctly. It is possible. For example, it is conceivable that dust or the like adheres between the measurement reference surface 2a and the sample mirror 6 or between the measurement reference surface 2a and the reference jig 15 to cause a deviation in height. Therefore, when a measurement result in such an allowable range is obtained, the control unit 14 invalidates the zero reset.
Then, a message prompting the user to redo the 0 reset process and the reference jig measurement process is displayed on the display unit 14a. Then, the operation for executing the focal position measurement process is locked, and the focal position measurement cannot be performed unless the zero reset process and the reference jig measurement process are performed again.

When a display to redo the 0 reset process appears, the measurer cleans the measurement reference surface 2a and then performs the 0 reset operation again. Then, after cleaning the receiving surface of the reference jig 15, it is reset on the measurement reference surface 2a and the reference jig measurement operation is performed again.
Then, the above procedure is repeated until the 0 reset redo display disappears.

Next, a focal position measurement process is performed as follows.
First, the objective lens 1 to be tested is set on the work stage 2 by bringing the mounting reference surface 1 b of the lens barrel 1 a into contact with the measurement reference surface 2 a of the work stage 2. At this time, the sample mirror 6 is moved in the vicinity of the focal position of the objective lens 1 to be examined.
In this state, measurement light is emitted from the laser light source 3. The measurement light passes through the half mirror 8, is reflected by the mirror 4, and enters the collimating lens 5.
Since the collimator lens 5 is collimated in advance so that the divergent light from the laser light source 3 is converted into a parallel beam, the collimate lens 5 emits a parallel beam.
The parallel light beam enters the objective lens 1 through the guide hole 2b and forms an image at the focal position of the objective lens 1.

When the sample mirror 6 is disposed at the focal position of the test objective lens 1, the measurement light reflected by the sample mirror 6 re-enters the test objective lens 1 to become a parallel light beam, and becomes a collimating lens. 5 is imaged at a position that becomes confocal with the laser light source 3. That is, after being reflected by the mirror 4 and the half mirror 8, an image is formed at the position of the pinhole 9.
Therefore, the total amount of light incident on the pinhole 9 passes through the pinhole 9 and is received on the light receiving element 10.
On the other hand, when the specimen mirror 6 is displaced from the focal position of the objective lens 1 to be examined, an image is formed at a position displaced in the optical axis direction from the pinhole 9 through the same optical path. Therefore, on the pinhole 9, the light beam spreads in a range wider than the hole diameter of the pinhole 9, so that a part of the light beam is shielded by the pinhole 9. Accordingly, the amount of light received by the light receiving element 10 is reduced.

Therefore, in the focal position measurement step, when it is confirmed that the measurement light is incident on the light receiving element 10 in the initial state described above, the control unit 14 drives the moving mechanism 7 to change the position of the sample mirror 6 to the optical axis. Move up (or down) in the direction. Then, from this state, the sample mirror 6 is gradually moved downward (or upward) toward the initial setting position. Then, the moving position of the sample mirror 6 measured by the laser length measuring machine 11 and the amount of light received by the light receiving element 10 are measured at appropriate sampling intervals. Then, the position of the sample mirror 6 where the amount of light received by the light receiving element 10 is maximum in the optical axis direction is obtained, and this position is used as a measurement value of the focal position of the objective lens 1 to be examined.
At this time, if the detected temperature of the temperature sensor 12 is within a predetermined temperature range from the temperature at the time of the zero reset operation, the focus position measurement is normally terminated.
On the other hand, when the temperature detected by the temperature sensor 12 exceeds a predetermined temperature range during measurement, a warning is displayed on the display unit 14a, thereby interrupting the focus position measurement operation.
In this case, the measurer starts over from the zero reset process and the reference jig measurement process, and then remeasures the focal position.

  As described above, according to the focal position measuring apparatus 100 of the present embodiment, the temperature sensor 12 monitors the change in the measured atmosphere temperature, so that the temperature change from the zero reset operation is within the predetermined temperature range. In addition, since the focal position can be measured, accurate measurement can be performed.

  In this embodiment, the ambient temperature around the objective lens 1 to be examined is measured, and the temperature inside the apparatus main body 18, for example, the ambient temperature in the optical path from the collimating lens 5 to the pinhole 9 is not measured. . This is because the focal length of the collimating lens 5 is sufficiently longer than the focal length of the objective lens 1 to be examined, and even if a temperature fluctuation of about 1 ° C. occurs, the measurement accuracy is not affected.

Next, a first modification of the present embodiment will be described.
FIG. 5 is a schematic front view showing a measured optical system and a measured optical system holding unit of a focal position measuring apparatus according to a first modification of the embodiment of the present invention. FIG. 6 is a schematic perspective view showing a measured optical system holding part of a focal position measuring apparatus according to a first modification of the embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing a measured optical system and a measured optical system holding unit of a focal position measuring apparatus according to a first modification of the embodiment of the present invention.

The focal position measurement apparatus 101 of this modification includes a work stage 16 (measurement optical system holding unit) instead of the work stage 2 in the focal position measurement apparatus 100 of the above embodiment. Hereinafter, a description will be given focusing on differences from the above embodiment.
As shown in FIGS. 5 and 6, the work stage 16 is composed of a plate member having a guide hole 16b similar to the guide hole 2b of the work stage 2 in the center, and the guide hole 16b on the upper surface 16a side in the vicinity of the guide hole 16b. Are provided with three receiving portions 17 made of steel balls or the like at positions that divide the portion into three in the circumferential direction. For this reason, as shown in FIG. 7, the reference mounting surface 1 b of the objective lens 1 to be tested is supported at three points on the work stage 16 by the three receiving portions 17.

According to this modification, the test objective lens 1 is supported at three points by the three receiving portions 17 instead of the measurement reference plane 2a, so that the mounting reference plane 1b of the test objective lens 1 and the work stage 16 are supported. Alternatively, dust or the like is hardly sandwiched between the reference jig 15 and the work stage 16.
Therefore, the possibility that the measurement of the zero reset operation or the reference jig measurement operation fails due to dust or the like being sandwiched is reduced, and efficient focus position measurement can be performed.
Further, since the contact area between the objective lens 1 and the work stage 16 becomes very small at the time of measurement, heat exchange between them hardly occurs, and even when the objective lens 1 is replaced and continuous measurement is performed. The influence of the temperature change due to the contact of the objective lens 1 to be examined is reduced, and the measurement temperature environment is easily stabilized.

Next, a second modification of the present embodiment will be described.
In the present modification, the temperature measurement of the length measurement amount of the laser length measuring machine 11 is performed according to the temperature detected by the temperature sensor 12. As parameters for performing temperature correction, various parameters that affect measurement due to temperature changes are set as necessary. For example, when the laser light source 3 causes a wavelength change due to a temperature change, based on the temperature change of the temperature sensor 12, the control unit 14 calculates and corrects the change in the focal position due to the wavelength variation. In addition, when the support column 13 that supports the laser length measuring device 11 expands and contracts due to a temperature change, the control unit 14 calculates the expansion / contraction amount and corrects the measurement result of the laser length measuring device 11.
By performing such temperature correction, the measurement accuracy of the focal position can be improved.
In addition, according to the present modification, even if the ambient temperature around the objective lens 1 to be examined changes to some extent, the length measurement result of the laser length measuring machine 11 is temperature-corrected, so that the temperature range in which the zero reset process is repeated is performed. The range can be expanded. In this case, since the frequency of redoing the zero reset process can be reduced, measurement can be performed more efficiently while maintaining measurement accuracy.

In the above description, the example of using the laser length measuring machine 11 is described as the movement amount detection mechanism for detecting the movement amount of the reflection mirror. However, if the position of the reflection mirror can be detected with a desired accuracy, The movement amount detection mechanism is not limited to the laser length measuring device. For example, a mechanical position detection mechanism or a linear encoder may be used.
In the above description, the laser length measuring device 11 has been described as an example in which the amount of movement of the moving mechanism 7 is detected by detecting the position of the sample mirror 6 integrated with the moving mechanism 7. As long as the movement amount of the reflection mirror can be accurately obtained, the movement amount detection mechanism may be a mechanism that detects the movement amount of the movement mechanism 7.
In the above description, the upper surface position of the sample mirror 6 is set as the measurement origin. However, the present invention is not limited to this, and a member attached to the sample mirror so as to move up and down integrally with the sample mirror 6 is used as one of the sample mirrors 6. The measurement origin may be set at the position of this member.

It is a typical front view which shows schematic structure of the focus position measuring apparatus which concerns on embodiment of this invention. It is typical sectional drawing which shows the measured optical system and measured optical system holding | maintenance part of the focus position measuring apparatus which concern on embodiment of this invention. It is a control block diagram of the focus position measuring apparatus which concerns on embodiment of this invention. It is a schematic diagram explaining 0 reset operation | movement and reference | standard jig | tool measurement operation | movement of the focus position measuring apparatus which concerns on embodiment of this invention. It is a typical front view showing a measured optical system and a measured optical system holding part of a focal position measuring device concerning the 1st modification of an embodiment of the present invention. It is a typical perspective view which shows the to-be-measured optical system holding | maintenance part of the focus position measuring apparatus which concerns on the 1st modification of embodiment of this invention. It is typical sectional drawing which shows the measured optical system and measured optical system holding | maintenance part of the focus position measuring apparatus which concern on the 1st modification of embodiment of this invention.

Explanation of symbols

1 Objective lens (Optical system to be measured)
2,16 Work stage (Measurement system holder)
1b Reference mounting surface 2a Measurement reference surface (reference position)
3 Laser light source 5 Collimating lens (imaging lens)
6 Specimen mirror (reflection mirror)
7 Moving mechanism 9 Pinhole (imaging position detection mechanism)
10 Light receiving element (imaging position detection mechanism)
11 Laser length measuring machine (movement amount detection mechanism)
DESCRIPTION OF SYMBOLS 12 Temperature sensor 13 Support | pillar part 14 Control part 14a Display part 15 Reference | standard jig | tool 17 Receiving part 100,101 Focus position measuring apparatus

Claims (3)

A focus position measuring apparatus that measures a focus position from a reference position by making measurement light incident on an optical system to be measured and detecting an imaging position,
A measured optical system holding unit that holds the measured optical system at the reference position;
A light source unit for allowing a parallel light beam to be incident as measurement light on the optical system to be measured;
A reflection mirror that reflects the measurement light transmitted through the optical system to be measured in an optical axis direction;
A moving mechanism for moving the reflecting mirror along the optical axis;
An imaging lens that forms an image of light re-incident on the optical system to be measured via the reflection mirror;
An imaging position detection mechanism for detecting an imaging position of light transmitted through the imaging lens;
A movement amount detection mechanism for detecting a movement amount of the reflection mirror that is supported and moved by the movement mechanism;
A temperature sensor for detecting an ambient temperature around the measured optical system held by the measured optical system holding unit;
A focus position measuring apparatus, wherein a warning display prompting resetting of the measurement origin is performed according to the temperature detected by the temperature sensor.   The focal position measurement apparatus according to claim 1, wherein the movement amount detected by the movement amount detection mechanism is corrected in accordance with a detection output of the temperature sensor.   The focal position measurement apparatus according to claim 1, wherein the measured optical system holding unit supports the measured optical system at three points.

Images