JP2011170074A - Attachment lens and fluorescence measuring device to which the same is attached - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-performance attachment lens which can suppress the reduction of an ambient light quantity and the occurrence of color shading, and can photograph a wide area, while reducing the weight and size with a small number of lenses; and to provide a fluorescence measuring device provided with the attachment lens. <P>SOLUTION: The attachment lens PA for correcting optical performance forms the fluorescent image of a sample S, in such a state that the attachment lens PA is combined with a master lens PB. The attachment lens PA is telecentric on the side of the sample S and includes an exit pupil in the vicinity of the entrance pupil of the master lens PB. The attachment lens PA includes: three groups of a first group Gr1 having positive power; a second group Gr2 having negative power; and a third group Gr3 having positive power in order from the side of the sample S, as a lens group having optical power, wherein, the first group Gr1 includes one Fresnel lens or two or more lenses made of the same glass material, and the second group Gr2 and the third group Gr3 include one single lens respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an attachment lens and a fluorescence measurement device equipped with the attachment lens. For example, a fluorescence measurement device such as a fluorescence imaging device or a fluorescence photometric measurement device, and an imaging optical system mounted thereon, for correcting optical performance. The present invention relates to an attachment lens.

  In the field of biochemistry and molecular biology, a fluorescence measuring apparatus is used that photographs a sample that emits fluorescence by excitation light or a sample that is stained with a fluorescent reagent and measures its concentration, shape, color, and the like. In measurement using a fluorescence measuring apparatus, a whole microplate (cell culture container) in which a sample (for example, cultured cells) is accommodated in a number of wells is photographed at once with a camera unit, and each well is measured based on the photographed image. In general, the concentration, shape, color, chemiluminescence / fluorescence intensity, etc. of the contained sample are quantified.

  When photographing with a fluorescence measuring device is performed with an ordinary photographing lens, the principal ray entering the photographing lens from the sample located in the periphery of the microplate (near the outer edge of the container in the well in the container) is relative to the optical axis of the photographing lens. It becomes diagonal. For this reason, the wall surface of the well is reflected, and the bottom surface of the well cannot be photographed. In order to prevent this, correction is generally performed by installing an attachment lens such as a Fresnel lens in the vicinity of the microplate to make it telecentric on the object side (see, for example, Patent Documents 1 and 2). Further, instead of using an existing imaging lens as a master lens and correcting it with an attachment lens, a newly designed imaging optical system as a whole has been proposed (see, for example, Patent Documents 3 and 4).

JP 2000-74837 A JP 2004-151565 A US Pat. No. 6,198,577 JP 2003-195166 A

  The configurations proposed in Patent Documents 1 and 2 are simple, but the number of lenses of the attachment lens is small, so that the pupil matching with the subsequent master lens cannot be performed satisfactorily. In other words, the spherical aberration of the pupil in the vicinity of the incident position of the master lens cannot be corrected, and the principal ray from the sample located in the peripheral portion of the microplate is strongly bent. For this reason, the amount of light incident on the master lens is reduced, and the amount of peripheral light on the image plane is reduced.

  In addition, as a type of fluorescence measuring apparatus that irradiates excitation light with epi-illumination (coaxial illumination), one that includes a fluorescence cube in which an excitation filter, a dichroic mirror, and an absorption filter are unitized is known. In a configuration as proposed in Patent Documents 1 and 2, if a fluorescent cube is arranged immediately before the master lens, the color ray shading occurs greatly because the incident angle of the principal ray on the dichroic mirror varies depending on the object height. . In other words, since the incident angle of the light beam to the dichroic mirror is greatly different between the central portion and the peripheral portion of the microplate, the light spectrum shifts to the short wavelength side as the sample is farther from the central portion of the microplate.

  In the configuration proposed in Patent Document 3, the entire imaging optical system is configured as a dedicated lens so that the luminous flux is not vignetted by the lens frame, but the size is large (total length 1.6 m), the number of lenses is large, and the weight is large. There is a problem that is heavy. Moreover, since it has a complicated configuration, it is difficult to assemble, and it is difficult to secure a space for arranging the fluorescent cubes.

  In the configuration proposed in Patent Document 4, the first to third lens groups constituting the sample-side collimator section are independently subjected to aberration correction, so there is a problem that the number of lenses is large and the weight is heavy. is there. In addition, since the number of contact surfaces with the air is increased by the number of lenses, the amount of stray light generated due to surface reflection is large, which is disadvantageous for weak fluorescence photography.

  The present invention has been made in view of such a situation, and the object thereof is to achieve a reduction in the amount of peripheral light, suppression of occurrence of color shading, and shooting of a large area while achieving light weight and downsizing with a small number of lenses. It is an object to provide a high-performance attachment lens capable of realizing the above and a fluorescence measuring apparatus including the same.

  In order to achieve the above object, an attachment lens of the present invention is an attachment lens for optical performance correction that forms a fluorescent image of a measurement object in combination with a master lens, and is telecentric on the measurement object side. Yes, a lens group having an exit pupil near the entrance pupil of the master lens and having optical power, in order from the measurement object side, a first group of positive power, a second group of negative power, and a positive group The third group of power, and the first group is composed of one Fresnel lens or two or more lenses made of the same glass material, and the second group and the third group are respectively It is composed of a single lens.

  According to this configuration, since the object to be measured is telecentric and the exit pupil is located near the entrance pupil of the master lens, the entire measurement object positioned over a large area can be photographed at a time. . Since it has a positive and negative power arrangement, it is possible to erase the magnification with a small number of lenses, and it is possible to suppress a decrease in the amount of peripheral light of the captured image and the occurrence of color shading. The first group is composed of one Fresnel lens or two or more lenses made of the same glass material, and the second group and the third group are each composed of one single lens, so the number of lenses is reduced. In addition, unnecessary surface reflection due to the interface between the glass and air is reduced, and a measurement object that generates weaker fluorescence can be imaged.

  The attachment lens of the present invention has a configuration in which a fluorescence cube that performs optical path separation between excitation light that illuminates the measurement object and fluorescence generated in the measurement object is provided between the third group and the master lens. May be.

  In the attachment lens of the present invention, it is easy to secure a space for placing the fluorescent cube. Therefore, according to this configuration, the amount of color shading can be reduced, and the amount of peripheral light is reduced due to vignetting of the lens frame of the master lens. Can also be suppressed.

The attachment lens of the present invention preferably satisfies the following conditional expression (1).
| Φ1 + φ2 + φ3 | <0.002 (1)
However,
φ1: Power of the first group (mm ^-1 ),
φ2: Power of second group (mm ⁻¹ ),
φ3: Third group power (mm ⁻¹ ),
It is.

  According to this configuration, it is possible to satisfactorily correct field curvature.

The attachment lens of the present invention preferably satisfies the following conditional expression (2).
d3> 40 (2)
However,
d3: Distance from the third group to the exit pupil of the attachment lens (mm),
It is.

  According to this configuration, a space for satisfactorily separating the optical path between excitation light and fluorescence can be secured.

The attachment lens of the present invention preferably satisfies the following conditional expressions (3) to (6).
ν1 ≧ 55 (3)
ν2 ≧ 55 (4)
ν3 ≧ 55 (5)
| Ν2-ν3 | ≦ 20 (6)
However,
ν1: Abbe number of the first group,
ν2: Abbe number of the second group,
ν3: Abbe number of the third group,
It is.

  According to this configuration, it is possible to satisfactorily correct lateral chromatic aberration.

  The fluorescence measurement device of the present invention includes an attachment lens according to the present invention, a master lens arranged so that the pupil matches the attachment lens as a collimator optical system, and an imaging device that records a fluorescence image formed by the master lens. And an illumination device for exciting the fluorescent sample.

  According to this configuration, a high-quality fluorescent image and an accurate measurement result can be obtained.

  According to the present invention, it is possible to realize a high-performance attachment lens that can reduce the amount of peripheral light, suppress the occurrence of color shading, and can shoot a wide area while achieving light weight and size reduction with a small number of lenses. . And by providing the attachment lens which concerns on this invention, it becomes possible to implement | achieve the fluorescence measuring apparatus from which a high quality fluorescent image and an exact measurement result are obtained.

The perspective view which shows typically the example of schematic structure of the fluorescence measuring apparatus which concerns on this invention. The horizontal sectional view which shows typically the example of schematic structure of the fluorescence measuring apparatus which concerns on this invention. 1 is a vertical sectional view schematically showing a schematic configuration example of a fluorescence measuring apparatus according to the present invention. 1 is an optical path diagram showing an optical configuration of a first embodiment (Example 1). The optical path figure which shows the optical structure of 2nd Embodiment (Example 2). FIG. 3 is an aberration diagram illustrating spherical aberration, astigmatism, distortion, and lateral chromatic aberration of Example 1. FIG. 6 is an aberration diagram illustrating spherical aberration, astigmatism, distortion, and lateral chromatic aberration in Example 2. FIG. 4 is a lateral aberration diagram of Example 1. FIG. 4 is a lateral aberration diagram of Example 2.

  Hereinafter, an attachment lens, a fluorescence measuring apparatus, and the like according to the present invention will be described. An attachment lens according to the present invention is an optical performance correction attachment lens that forms a fluorescent image of a measurement object in a state of being combined with a master lens, is telecentric on the measurement object side, and an exit pupil is disposed on the master lens. Near the entrance pupil of the lens. And as a lens group having optical power, there are three groups of a first group of positive power, a second group of negative power, and a third group of positive power in order from the measurement object side ( Power: an amount defined by the reciprocal of the focal length), the first group is composed of one Fresnel lens or two or more lenses made of the same glass material, and each of the second group and the third group is 1 It consists of a single lens.

  When a telecentric attachment lens is placed on the measurement object side so that its exit pupil is located near the entrance pupil of the master lens, it can be attached to any part of the measurement object (sample on the entire microplate). Since the chief ray entering the lens is parallel to the optical axis, it is possible to satisfactorily capture the entire bottom surface of the well of the microplate. Therefore, it is possible to take an image of the entire measurement object located over a large area at a time.

  By adopting positive and negative power arrangement, it is possible to configure a collimator optical system capable of effectively correcting optical performance in combination with the master lens. When combined with a master lens, the telecentric attachment lens on the object side acts as a collimator optical system so that the fluorescence generated from the measurement object is collected and emitted from the exit pupil as approximately parallel light. The imaging magnification β of the entire optical system is β = −fm / fa (fm: focal length of the master lens, fa: focal length of the attachment lens). Accordingly, since the total magnification when combined with the master lens can be determined by β = −fm / fa, a tandem configuration can also be adopted. For example, if the object to be photographed is a microplate of general size 128 mm × 85 mm and the image sensor is a 2/3 inch CCD element (light receiving surface size 8.8 mm × 6.6 mm), the imaging magnification of the entire optical system If the value is smaller than 0.069 times (= 8.8 mm / 128 mm), the entire container can be photographed. For this reason, in the embodiment described later, the focal length fm of the master lens is 28 mm, the focal length of the attachment lens is fa≈500 mm, and the imaging magnification is about −0.056.

  In addition, in the attachment lens having the positive and negative power arrangement, the height of the paraxial light beam from the measurement object becomes a positive value for all of the first group, the second group, and the third group, and the paraxial light beam from the pupil. Is negative for all of the first group, the second group, and the third group. Therefore, the sign of the occurrence of chromatic aberration of magnification is negative and positive in addition to the positive and negative power arrangement. As a result, an effect of canceling out the lateral chromatic aberration by the three lens groups occurs. With this action, it is possible to achromatic all magnifications in the entire three groups from the conditions of power and Abbe number without using a bonded lens. Therefore, since it is not necessary to achromatic each lens group, the number of lenses used can be reduced.

  If positive and negative combination lenses are used in the second and third lens groups in order to correct lateral chromatic aberration, the number of lenses increases and the amount of surface reflection at the interface between glass and air increases. For this reason, positive and negative combination lenses are not suitable for photographing weak fluorescence (one thousandths to several tens of thousands of illumination energy). In addition, since a lens having a large effective diameter is required for the collimator unit, a positive / negative combination lens or a positive / negative bonded lens increases the weight of the lens unit and the lens barrel unit. On the other hand, if the first group is composed of one Fresnel lens or two or more lenses made of the same glass material, and the second group and the third group are each composed of one single lens, the number of lenses can be reduced. In addition, since unnecessary surface reflection due to the interface between the glass and air can be reduced, it is possible to image a measurement object that generates weaker fluorescence.

  If correction with an attachment lens is performed with only positive power, the luminous flux is strongly bent at the periphery of the screen (spherical aberration of the pupil), so the amount of light incident on the master lens is reduced at the periphery of the screen compared to the center of the screen. . On the other hand, in an attachment lens having positive and negative power arrangements, the spherical aberration of the pupil that occurs in the positive power lens group can be corrected by the second group of negative power, so the matching of the pupil with the master lens is good Therefore, it is possible to prevent the light flux from the measurement object from being vignetted at the opening of the fluorescent cube, the lens barrel of the master lens, and the like, thereby causing a decrease in the peripheral light amount. Therefore, it is possible to perform fluorescence imaging while suppressing a decrease in the amount of peripheral light of the captured image.

  A type of fluorescence measuring apparatus that irradiates excitation light with epi-illumination is known to have a fluorescence cube that is a unit of excitation filter, dichroic mirror, and absorption filter. When the cube is arranged, as described above, since the incident angle of the principal ray with respect to the dichroic mirror varies depending on the object height, a large amount of color shading occurs. On the other hand, in the attachment lens having positive and negative power arrangement, the angle of the off-axis light beam bent in the first group can be reduced by the negative power of the second group before the light beam passes through the fluorescent cube installation position. Therefore, it is possible to make the incident angle of light incident on the dichroic mirror small. Therefore, the amount of color shading generated can be reduced. Since the light incident angle to the master lens is also reduced, it is possible to suppress a decrease in the amount of peripheral light due to vignetting of the lens frame of the master lens.

  According to the characteristic configuration described above, a high-performance attachment lens that can reduce the amount of peripheral light, suppress the occurrence of color shading, and shoot a large area while achieving light weight and size reduction with a small number of lenses. Can do. In addition, an existing photographing lens (for example, a general Leica-like photographic lens) can be used as it is as a master lens (main lens system), and the fluorescence of the measurement object is combined with the master lens. As an optical performance correction attachment lens for forming an image, it is possible to achieve a reduction in the amount of light by reducing the number of sheets, a reduction in size, a reduction in cost, etc. while maintaining a sufficient optical performance. And by providing the attachment lens which concerns on this invention, it becomes possible to implement | achieve the fluorescence measuring apparatus from which a high quality fluorescent image and an exact measurement result are obtained. The conditions for achieving such effects in a well-balanced manner and achieving higher optical performance, lighter weight, and the like will be described below.

  It is desirable that the attachment lens has a fluorescence cube for performing optical path separation between excitation light for illuminating the measurement object and fluorescence generated by the measurement object between the third group and the master lens. According to the configuration of the attachment lens described above, it is easy to secure a space for arranging the fluorescent cube. Even if the fluorescent cube is arranged between the third group and the master lens, as described above, the color shading can be performed. The amount of generated light can be reduced, and a decrease in peripheral light amount due to vignetting of the lens frame of the master lens can also be suppressed. Therefore, it is preferable to set the position of the optical path separation between the excitation light and the fluorescence between the third group and the master lens.

It is desirable to satisfy the following conditional expression (1).
| Φ1 + φ2 + φ3 | <0.002 (1)
However,
φ1: Power of the first group (mm ^-1 ),
φ2: Power of second group (mm ⁻¹ ),
φ3: Third group power (mm ⁻¹ ),
It is.

  Conditional expression (1) defines a preferable condition range for setting the Petzval sum of the attachment lens to a value close to zero. Assuming that the size of the image sensor is 10 mm (diagonal size of the light receiving surface) and a double Gauss or retrofocus type imaging lens having a focal length of 28 mm is used as the master lens, the Petzval sum of the master lens is approximately 0. A value of 0.005 to 0.008. Also, the Petzval sum of the attachment lens: Pz is Pz = φ1 / n1 + φ2 / n2 + φ3 / n3 (n1: refractive index of the first group, n2: refractive index of the second group, n3: refractive index of the third group). However, when the refractive index of glass is approximated as n1 = n2 = n3 = n = 1.5, the condition of Pz = 0 can be expressed as n (φ1 + φ2 + φ3) = φ1 + φ2 + φ3 = 0. If the conditional expression (1) is satisfied, the Petzval sum of the attachment lens is approximately Pz <0.002 / n (= 1.5) = 0.0013, which does not greatly affect the Petzval sum of the master lens. . On the other hand, the Petzval sum of the attachment lens portion increases positively or negatively as it deviates from this condition range, and the influence on the Petzval sum of the master lens becomes large, and the aberration correction balance of the master lens is lost. Therefore, when the conditional expression (1) is satisfied, it is possible to correct the field curvature favorably.

It is desirable to satisfy the following conditional expression (2).
d3> 40 (2)
However,
d3: Distance from the third group to the exit pupil of the attachment lens (mm),
It is.

  Conditional expression (2) defines a preferable condition range for securing a space for installing the fluorescent cube in the vicinity of the aperture stop position. Assuming an attachment lens placed in front of an existing master lens, if a space satisfying conditional expression (2) is secured, the optical path separation between the excitation light and the fluorescence can be performed satisfactorily with the fluorescent cube. Further, it is more preferable to satisfy 90> d3> 60.

It is desirable to satisfy the following conditional expressions (3) to (6).
ν1 ≧ 55 (3)
ν2 ≧ 55 (4)
ν3 ≧ 55 (5)
| Ν2-ν3 | ≦ 20 (6)
However,
ν1: Abbe number of the first group,
ν2: Abbe number of the second group,
ν3: Abbe number of the third group,
It is.

  For example, when the measurement object is a sample obtained by staining cells with a fluorescent reagent, the fluorescent reagent is photographed as a set of discrete point light sources when receiving excitation light. Misalignment will be noticeable. In other words, when image processing operations such as combining RGB images (monochromatic images) stained with a plurality of fluorescent reagents and superimposing them to see the state of cell distribution are performed, color misregistration occurs. This mainly needs to be corrected. Conditional expressions (3) to (6) define a preferable condition range for effectively performing magnification achromaticity in a configuration in which the second group and the third group are each composed of one single lens. By satisfying the conditional expressions (3) to (5), it is possible to configure each lens group with a crown system or a synthetic quartz optical glass having a high ultraviolet light transmittance. Conditional expression (6) defines a condition in which the chromatic aberration of magnification is canceled by the second group and the third group when the conditional expressions (3) to (5) are satisfied. If the condition range of the conditional expression (6) is not satisfied, the chromatic aberration of magnification increases, so that it is difficult to correct aberrations with a simple lens configuration. Therefore, it is possible to satisfactorily correct lateral chromatic aberration by satisfying conditional expressions (3) to (6).

  From the same viewpoint as described above, it is preferable to satisfy ν1> 60, ν2> 50, ν3> 60, and it is further preferable to satisfy 58 <ν1 <70, 56 <ν2 <70, 58 <ν3 <70. In consideration of the generality of the glass material that satisfies the above Abbe number conditional expressions (3) to (6), the refractive index n of the lens used in each lens group preferably satisfies n <1.55.

For example, in consideration of the focal length fm = 28 mm of an easy-to-use master lens and the range in which the imaging magnification is suitable for imaging with 2/3 inch and 1/2 inch CCD elements, the following conditional expression It is desirable to satisfy (7), and it is more desirable to satisfy conditional expressions (3) to (7).
400 ≦ fa ≦ 600 (7)
However,
fa: Focal length (mm) of the attachment lens,
It is.

  Some fluorescent reagents require ultraviolet excitation, such as Tryptophan, DAPI, FURA2, and tetracycline. For this reason, when the fluorescent cube is arranged in the vicinity of the aperture position so as to perform coaxial epi-illumination, it is necessary to use a material that does not decrease transmittance with ultraviolet light as a glass material that constitutes the attachment lens. Specific examples of such glass materials include synthetic quartz for the first group, K10 for the second group, and BK7 for the third group. High refractive index glass containing lanthanum, barium, etc. tends to have poor transmittance in the ultraviolet region, and is not desirable for fluorescent imaging that requires ultraviolet excitation.

  Realizing a fluorescence measurement device that can provide high-quality fluorescence images and accurate measurement results by including the attachment lens described above and a master lens arranged so that the pupil matches the attachment lens as a collimator optical system It becomes possible to do. A schematic configuration example of the fluorescence measuring apparatus is schematically shown in FIGS. 1 schematically shows the external appearance of the main part of the fluorescence measuring apparatus 10, FIG. 2 schematically shows a horizontal sectional structure of the fluorescence measuring apparatus 10, and FIG. 3 shows a vertical sectional structure of the fluorescence measuring apparatus 10. Is schematically shown.

  The fluorescence measuring apparatus 10 includes a light source unit 1, a camera unit 2, an image pickup optical system OP, and the like. The image pickup optical system OP includes an attachment lens PA (correction lens system) and a master lens (main lens system) PB. ing. The attachment lens PA has a first group Gr1, a folding mirror MR, a second group Gr2, a third group Gr3, and a fluorescent cube CU in order from the microplate 3 side. The light source unit 1 includes a lamp 1a, a light pipe. 1b and a condenser lens 1c.

  As shown in FIG. 1, the fluorescence measuring apparatus 10 spectrally converts the white light L1 from the light source unit 1 into excitation light L2 with the fluorescence cube CU, and the sample S set on the microplate 3 is excited with light L2 (illumination). It is configured to generate fluorescence L3 (observation light) by epi-illumination with light. In addition, a plurality of fluorescent cubes CU are installed, and one of the fluorescent cubes CU is selected and replaced at a predetermined position by a turret type exchange mechanism (X: turret shaft in FIGS. 2 and 3). It is possible to do.

  The fluorescent cube CU incorporates an excitation filter, a dichroic mirror, an absorption filter, and the like, and separates the optical path of the fluorescence L3 emitted from the sample S from the excitation light L2 by the dichroic mirror. Further, the plurality of fluorescent cubes CU have different built-in excitation filters or the like so that the wavelengths of the emitted excitation light L2 are different from each other. Therefore, it is possible to switch the wavelengths of the excitation light L2 and the fluorescence L3 by exchanging the fluorescent cube CU with the exchange mechanism.

  When the white light L1 from the light source unit 1 enters the fluorescent cube CU and is irradiated to the excitation filter, excitation light L2 (for example, blue light) having a predetermined wavelength passes through the excitation filter. The excitation light L2 is reflected by the dichroic mirror (bending angle of the optical axis AX: 90 °), then exits from the fluorescent cube CU, and is irradiated onto the sample S by the attachment lens PA. For the sample S, for example, a fluorescent reagent that binds to calcium of osteoblasts cultured on an artificial bone so that green light fluorescence is generated when excited with blue illumination light (short wavelength excitation / long wavelength light emission). Is used. The fluorescence L3 (for example, green light) generated from the sample S passes through the attachment lens PA again, and then enters the fluorescence cube CU and passes through the dichroic mirror. And it permeate | transmits the absorption filter for improving S / N ratio, and inject | emits from the fluorescent cube CU. The fluorescence L3 emitted from the fluorescence cube CU passes through the master lens PB, enters the fluorescence measurement camera unit 2, and forms a fluorescence image IM on the light receiving surface of the image sensor SR. The fluorescent image IM is converted into an electrical signal by the imaging element SR, and the fluorescent image IM is photographed, measured, observed, and the like.

  FIGS. 4 and 5 show, as a specific optical configuration of the imaging optical system OP, the imaging optical system OP having the first and second embodiments of the attachment lens PA in an optical cross section. Each of the attachment lenses PA of the first and second embodiments is an optical performance correction attachment lens that forms the fluorescent image IM of the sample S in a state combined with the master lens PB, and is on the object surface OB side. Telecentric and has an exit pupil near the entrance pupil of the master lens PB. Further, as a lens group having optical power, three groups of a first group Gr1 having a positive power, a second group Gr2 having a negative power, and a third group Gr3 having a positive power are sequentially arranged from the object surface OB side. The first group Gr1 is composed of two lenses made of the same glass material, and the second group Gr2 and the third group Gr3 are each composed of a single lens.

  The master lens PB is a photography lens such as a general Leica size, and is shown as an ideal lens in FIGS. In any of the embodiments, the attachment lens PA disposed in front of the master lens PB is configured such that the first group Gr1 is composed of a biconvex positive lens and a positive meniscus lens convex on the object side, and the second group Gr2. Is composed of a negative meniscus lens concave on the image side, and the third lens unit Gr3 is composed of a positive meniscus lens convex on the image side. In the first embodiment, only the spherical surface is configured. In the second embodiment, the image side surface of the second group Gr2 and the image side surface of the third group Gr3 are configured as aspheric surfaces. In the second embodiment, the position of the second group Gr2 deviates from a position suitable for correction of distortion. In order to correct this, the image side surfaces of the single lenses of the second group Gr2 and the third group Gr3 are corrected. Is an aspherical surface. In addition, the first group Gr1 and the second group Gr2 are spaced from each other, and the 90 degree folding mirror MR can be easily arranged in the space.

  Since the attachment lens PA is telecentric on the measurement object S side and the exit pupil is located in the vicinity of the entrance pupil of the master lens PB, the entire measurement object S that is spread over a large area is photographed at a time. be able to. Since it has a positive and negative power arrangement, it is possible to erase the magnification with a small number of lenses, and it is possible to suppress a decrease in the amount of peripheral light of the captured image and the occurrence of color shading. Since the first group Gr1 is composed of two lenses made of the same glass material, and the second group Gr2 and the third group Gr3 are each composed of a single lens, the number of lenses can be reduced. At the same time, unnecessary surface reflection due to the interface between the glass and air is reduced, and it becomes possible to image a measurement object that generates weaker fluorescence. Therefore, a high-performance attachment lens PA that can reduce the amount of peripheral light, suppress the occurrence of color shading, and can shoot a wide area while achieving light weight and downsizing with a small number of lenses is realized.

  In the attachment lens PA, it is easy to secure a space for arranging the fluorescent cube CU. Therefore, according to the configuration having the fluorescent cube CU between the third group Gr3 and the master lens PB, the amount of color shading is reduced. It is also possible to suppress a decrease in the amount of peripheral light due to vignetting of the lens frame of the master lens.

  The attachment lens PA can satisfactorily correct field curvature by satisfying the conditional expression (1). By satisfying the conditional expression (2), it is possible to secure a space for satisfactorily performing optical path separation between excitation light and fluorescence. Further, by satisfying the conditional expressions (3) to (6), it is possible to satisfactorily correct lateral chromatic aberration.

  The fluorescence measuring apparatus 10 includes an attachment lens PA, a master lens PB arranged so that the pupil is matched using the attachment lens PA as a collimator optical system, and a camera unit 2 that records a fluorescence image IM formed by the master lens PB. And the light source unit 1 for exciting the fluorescent sample S, it is possible to obtain high-quality fluorescent images and accurate measurement results.

  Hereinafter, the configuration and the like of the attachment lens PA, the master lens PB, and the imaging optical system OP having the same according to the present invention will be described more specifically with reference to the construction data of the examples. Examples 1 and 2 (ex1, 2) listed here are numerical examples corresponding to the first and second embodiments described above, and represent the optical configurations of the first and second embodiments. The optical path diagrams (FIGS. 4 and 5) show the optical arrangement, optical paths, and the like of the corresponding first and second embodiments.

In the construction data of each example, as surface data, in order from the left column, surface number i, radius of curvature r (mm), on-axis surface interval d (mm), refraction with respect to d-line (wavelength 587.56 nm). The Abbe number vd and the effective diameter De for the rate nd and d lines are shown. In Example 2, the surface numbered with * is an aspheric surface, and the surface shape is expressed by the following equation (AS) using a local orthogonal coordinate system (x, y, z) with the surface vertex as the origin. ). A conic constant is shown as aspherical data (the coefficient of a term not described is 0).
z = (c · h ² ) / [1 + √ {1− (1 + K) · c ² · h ² }] + Σ (Aj · h ^j ) (AS)
However,
h: height in the direction perpendicular to the z axis (optical axis AX) (h ² = x ² + y ² ),
z: the amount of sag in the direction of the optical axis AX at the position of the height h (based on the surface vertex),
c: curvature at the surface vertex (the reciprocal of the radius of curvature r),
K: conic constant,
Aj: j-order aspheric coefficient,
It is.

  As various data, the focal length (f, mm) of the entire imaging optical system OP, F number (Fno.), Numerical aperture (NA) on the object side, maximum value of object height yob (mm), maximum value of image height yim (Mm), total lens length (TL, mm), back focus (BF, mm), image magnification (β), and the like. In the back focus BF, the distance from the lens final surface to the paraxial image surface is expressed in terms of air length, and the total lens length TL is obtained by adding the back focus BF to the distance from the lens front surface to the lens final surface. is there. In addition, Table 1 shows values of examples corresponding to each conditional expression.

  6 and 7 are aberration diagrams corresponding to Examples 1 and 2 (ex1 and 2, respectively), (A) is a spherical aberration diagram (mm), (B) is an astigmatism diagram (μm), ( C) is a distortion diagram (%), and (D) is a chromatic aberration diagram (μm). 6 and 7, the vertical axis pr is the entrance pupil radius (Example 1: 167.4380 mm, Example 2: 348.7123 mm), and the vertical axis yim is the image height (object height) on the light receiving surface of the image sensor SR. The maximum value of yob corresponds to 80 mm. (Mm). In the astigmatism diagram, T represents a tangential image plane (meridional image plane), and S represents a sagittal image plane.

  8 and 9 are lateral aberration diagrams corresponding to Examples 1 and 2 (ex1 and 2), respectively. 8 and 9, (A) and (B) are the object height yob = 0.00 mm, (C) and (D) are the object height yob = −40.00 mm, and (E) and (F) are the object heights. yob = −56.00 mm, (G), (H) respectively indicate lateral aberrations when the object height is yob = −80.00 mm, and (A), (C), (E), (G) are meridional. Transverse aberration of image (maximum scale of EY: ± 5 μm, maximum scale of PY: ± radius of entrance pupil), (B), (D), (F), (H) are lateral aberrations of sagittal image (maximum scale of EX : ± 5 μm, maximum scale of PX: ± incidence pupil radius). The broken line represents the F-line, the solid line represents the d-line, and the alternate long and short dash line represents each lateral aberration with respect to the C-line.

Example 1
Unit: mm
Surface data
ird nd vd De
Surface ∞ 46.500 160.00
1 496.153 22.000 1.45844 67.830 172.00
2 -513.044 1.000 172.00
3 170.640 24.000 1.45844 67.830 172.00
4 516.895 138.000 172.00
5 155.187 4.000 1.50137 56.409 70.00
6 59.513 130.100 70.00
7 -92.413 5.000 1.51680 64.167 40.00
8 -70.335 70.600 40.00
9 (Aperture ST) ∞ 28.000 14.84
10 (PB: ideal lens)-29.487 24.70
Image plane ∞ 9.07

Various data
f = 631.841
Fno. = 1.95
NA (object side) = 0.015
yob (maximum value) = 80
yim (maximum value) = 4.529
TL = 452.187
BF = 29.487
β = -0.0566
Entrance pupil position: 11114.78mm
Exit pupil position: 1 × 10 ¹⁰ mm
Focal length of attachment lens PA (i = 1 to 9: collimator from first surface to aperture): 516.1mm
Focal length of master lens PB (i = 10: ideal lens setting): 28mm
Object position (surface distance to the object surface): -46.5mm
Length from first side to aperture: 394.7mm

Example 2
Unit: mm
Surface data
ird nd vd De
Surface ∞ 46.500 160.00
1 603.444 19.000 1.45844 67.830 172.00
2 -694.837 1.000 172.00
3 221.810 20.000 1.45844 67.830 172.00
4 856.288 222.600 172.00
5 103.272 4.000 1.50137 56.409 56.00
6 * 49.542 69.500 56.00
7 -80.116 5.000 1.51680 64.167 44.00
8 * -57.565 71.600 44.00
9 (Aperture ST) ∞ 28.000 14.91
10 (PB: ideal lens)-29.594 24.79
Image plane ∞ 9.03

Aspherical data of 6th surface
K = 0.2549332

Aspherical data of 8th surface
K = 0.2115807

Various data
f = 1374.341
Fno. = 1.94
NA (object side) = 0.015
yob (maximum value) = 80
yim (maximum value) = 4.507
TL = 470.294
BF = 29.594
β = -0.0563
Entrance pupil position: 24350.31mm
Exit pupil position: 1 × 10 ¹⁰ mm
Focal length of attachment lens PA (i = 1 to 9: collimator from the first surface to the aperture): 507.5mm
Focal length of master lens PB (i = 10: ideal lens setting): 28mm
Object position (surface distance to the object surface): -46.5mm
Length from first side to aperture: 412.7mm

  In Examples 1 and 2 described above, different optical glasses are used for each of the first group, the second group, and the third group. However, the present invention is not limited to this, and any optical glass that satisfies the above conditional expression may be used. It is also possible to construct an attachment lens using the same optical glass for all three lens groups. For example, when synthetic quartz is used as the glass material of the first group, the second group, and the third group, a fluorescent photographing attachment lens capable of efficient coaxial epi-illumination of ultraviolet light can be configured.

  Various changes and modifications can be appropriately made to the embodiments and examples of the present invention within the scope of the technical idea shown in the claims. The above embodiments and examples are only one embodiment of the present invention, and the meanings of the terms of the present invention or each component are described in the above embodiments and examples. It is not limited to.

1 Light source unit (lighting device)
1a lamp 1b light pipe 1c condenser lens 2 camera unit (imaging device)
3 Microplate 10 Fluorescence measurement device OP Imaging optical system PA Attachment lens (collimator optical system)
PB Master lens CU Fluorescent cube Gr1 First group Gr2 Second group Gr3 Third group MR Folding mirror ST Aperture S Sample (measurement object)
SR Image sensor OB Object surface (object to be measured)
IM image plane (fluorescent image)
L1 White light L2 Excitation light L3 Fluorescence X Turret axis AX Optical axis

Claims (6)

  An optical performance correction attachment lens that forms a fluorescent image of a measurement object in combination with a master lens, is telecentric on the measurement object side, and has an exit pupil near the entrance pupil of the master lens. As a lens group having optical power, in order from the measurement object side, there are three groups of a first group of positive power, a second group of negative power, and a third group of positive power, The first group is composed of one Fresnel lens or two or more lenses made of the same glass material, and each of the second group and the third group is composed of one single lens. Attachment lens.   The fluorescent cube for performing optical path separation between excitation light for illuminating the measurement object and fluorescence generated in the measurement object is provided between the third group and the master lens. Attachment lens. The attachment lens according to claim 1, wherein the following conditional expression (1) is satisfied:
| Φ1 + φ2 + φ3 | <0.002 (1)
However,
φ1: Power of the first group (mm ^-1 ),
φ2: Power of second group (mm ⁻¹ ),
φ3: Third group power (mm ⁻¹ ),
It is. The attachment lens according to any one of claims 1 to 3, wherein the following conditional expression (2) is satisfied;
d3> 40 (2)
However,
d3: Distance from the third group to the exit pupil of the attachment lens (mm),
It is. The attachment lens according to any one of claims 1 to 4, wherein the following conditional expressions (3) to (6) are satisfied:
ν1 ≧ 55 (3)
ν2 ≧ 55 (4)
ν3 ≧ 55 (5)
| Ν2-ν3 | ≦ 20 (6)
However,
ν1: Abbe number of the first group,
ν2: Abbe number of the second group,
ν3: Abbe number of the third group,
It is.   An attachment lens according to any one of claims 1 to 5, a master lens arranged so that the pupil is matched using the attachment lens as a collimator optical system, and an imaging for recording a fluorescent image formed by the master lens A fluorescence measuring apparatus comprising: an apparatus; and an illumination device for exciting a fluorescent sample.

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