Abstract: A light emission microscope includes a low temperature detector array which receives light through a room temperature projection optics system from a device under test. A cold aperture including a movable cold stop and a cryogenic filter absorbs unwanted thermal radiation emitted by the optics system. In one embodiment, a high resolution CCD camera can be used with the low temperature detector array and camera with a computer-controlled mirror providing emitted light to both cameras.

Abstract: An objective lens includes a first lens group, a second lens group having a lens pair, a third lens group having a lens pair, a fourth lens group having a lens pair, a fifth lens group having a lens pair, and a sixth lens group. The objective lens is configured so as to satisfy the following conditional expressions: d/L<0.025 0.58<Rp/Rn<1.65 where L(mm) is the overall length of the objective lens; d(mm) is the air gap of each of the lens pair; Rp is the radius of curvature of each of positive refractive power surfaces opposing each other with the air gap therebetween; and Rn is the radius of curvature of a negative refractive power surface. Whereby, chromatic aberration can be corrected and resolution is exponentially improved without using a cemented lens, providing a deep ultra-violet objective lens with a high NA capable of auto focussing instantaneously.

Abstract: A two-wavelength antireflection film to prevent light in two-wavelength regions of a deep-ultraviolet region and a region from a visible region to the near-infrared region on a surface of a substrate by coating the two-wavelength antireflection film on the surface of the substrate which penetrates light from the deep-ultraviolet region to the near-infrared region, comprising a first thin film which is formed on the substrate, and has a refractive index of 1.6 to 2.0 and optical film thickness of 0.4&lgr; to 0.7&lgr; for design main wavelength (&lgr;), a second thin film which is formed on the first thin film, and has a refractive index of 1.35 to 1.55 and an optical film thickness of 0.05&lgr; to 0.6&lgr; for the design main wavelength &lgr;, a third thin film which is formed on the second thin film, and has a refractive index of 1.6 to 2.0 and an optical film thickness of 0.1&lgr; to 0.

Abstract: A two-wavelength antireflection film to prevent light in two-wavelength regions of a deep-ultraviolet region and a region from a visible region to the near-infrared region on a surface of a substrate by coating the two-wavelength antireflection film on the surface of the substrate which penetrates light from the deep-ultraviolet region to the near-infrared region, comprising a first thin film which is formed on the substrate, and has a refractive index of 1.6 to 2.0 and optical film thickness of 0.4&lgr; to 0.7&lgr; for design main wavelength (&lgr;), a second thin film which is formed on the first thin film, and has a refractive index of 1.35 to 1.55 and an optical film thickness of 0.05&lgr; to 0.6&lgr; for the design main wavelength &lgr;, a third thin film which is formed on the second thin film, and has a refractive index of 1.6 to 2.0 and an optical film thickness of 0.1&lgr; to 0.

Abstract: A liquid immersion photolithography system includes an exposure system that exposes a substrate with electromagnetic radiation, and also includes a projection optical system that focuses the electromagnetic radiation on the substrate. A liquid supply system provides a liquid between the projection optical system and the substrate. The projection optical system is positioned below the substrate.

Abstract: Microfabricated lenses, e.g., solid immersion lens (SIL) structures, are provided along with techniques for constructing these lens structures, as well as selected applications of such lens structures.

Abstract: A bi-convex solid immersion lens is disclosed. Unlike conventional plano-convex solid immersion lenses having a flat bottom surface, the disclosed lens has a convex bottom surface. The radius of curvature of the bottom surface is smaller than that of the object to be inspected. This construction allows for a more accurate determination of the location of the inspected feature, and enhances coupling of light between the immersion lens and the inspected object. The disclosed lens is particularly useful for use in microscope for inspection of semiconductor devices and, especially flip-chip (or chip scale) packaged devices. The immersion lens can also be incorporated in a read or read/write head of optical memory media.

Abstract: In a microscope objective arrangement comprising a microscope objective (1), which may be arranged in a microscope in a working position, such that a specimen (7) arranged in the visual field of the microscope objective (1) may be detected by the microscope objective (1), a video camera (12; 22; 25; 32) coupled with the microscope objective (1) is provided, which can detect at least part of the visual field, without interposition of the microscope objective (1), when the microscope objective (1) is in its working position.

Abstract: An microscope objective lens system comprises a first lens unit including a plurality of cemented lens components and converging light coming from an object, a second lens unit including a negative lens component having a strong concave surface on the image side, and a third lens unit including a cemented doublet composed of a negative lens element having a concave surface on the object side and a positive lens element, wherein the objective lens system satisfies the following conditions: 1.65≦nd≦1.8 25≦&ngr;d≦41 T360≧0.5 wherein nd and &ngr;d are refractive index at the Fraunhofer d-line and the Abbe's number of the positive lens element in the third lens unit, respectively, and T360 is an internal transmittance except for a reflection loss at 360 nm for 10 mm thickness of material forming the positive lens element in the third lens unit.

Abstract: A microscope optical system comprises an objective lens and an intermediate magnification varying part disposed just after the image side of the objective lens. A microscope objective lens according to another aspect of the invention comprises a first lens group and a second lens group in the mentioned order from the object side. The first lens group includes a positive meniscus lens with the concave surface facing the object side and one or more cemented lenses, the first lens group having a positive refractive power as a whole, at least one of the cemented lenses includes a lens made of a material having an Abbe's number equal to or larger than 80, and conditions 0.3≦wd/f≦0.45 and 0.6≦NA are satisfied, where f represents the focal length of the microscope objective lens as a whole, wd represents the working distance of the microscope objective lens, and NA represents the numerical aperture of the microscope objective lens.

Abstract: The invention relates to an objective (2) for stereomicroscopes of the telescope type which comprises three optical assemblies (G1, G2, G3), the first assembly (G1) being arranged towards the object side and the third assembly (G3) being arranged towards a magnification changer (3L, 3R). The proposed objective (2) meets the conditions 0.44≦ENP/F≦0.6, where ENP denotes the diameter of the entry pupil of the magnification changer (3L, 3R) at the maximum magnification and F denotes the focal length of the objective (2), and tan(w1)≧0.16, where w1 denotes the maximum field angle of the objective (2) at the lowest magnification of the magnification changer (3L, 3R). The proposed objective (2) makes it possible to use a stereomicroscope with maximum resolution and a field of vision which is adapted to the full range of magnifications of the microscope.

Abstract: A miniature microscope objective for a miniature microscope array (MMA) includes preferably at least three or four lenses including from object to image a first positive lens, a second positive lens and a third negative lens. The objective has a numerical aperture (NA) that provides diffraction limited performance, and is preferably between 0.4 and 0.9 for the four lens design. The magnification of the objective is below approximately the outer diameter (OD) divided by the field of view (FOV), and is preferably between approximately 1 and 12, and is further preferably greater than 4. The ratio of magnification (M) to numerical aperture (NA) for the objective thereby has a magnitude that is less than substantially 30.

Abstract: An SIM (solid immersion mirror) made principally of a light-permeable high-refractive-index medium has a lower surface which is produced by rotating a parabola about a symmetry axis, and an upper surface which is a perpendicular bisector surface of a line segment connecting the vertex and the focus of the parabola. The upper surface has the property of transmitting collimated light incident in a direction perpendicular thereto and reflecting the light reflected from the lower surface. Such a structure of the SIM facilitates the design of the upper surface and the lower surface both of which are reflecting surfaces, and allows the light to be incident on a light focusing point uniformly from therearound, thereby to form a proper light spot at the light focusing point. Additionally, the SIM allows the light to enter the medium through the entire upper surface, to achieve effective use of light.

Abstract: A liquid immersion type microscope objective lens includes, in sequence from an object side, a first lens group containing meniscus lenses with their concave surfaces toward an object and having positive refractive power, a second lens group having the positive refractive power, and a third lens group having negative refractive power, wherein a distance from an object surface to a first lens surface of said first lens group is larger than a focal length f of a whole objective lens system, and a radius of curvature r1 of the first lens surface in relation to the focal length f satisfies a relation such as 4<|r1/f|<7.

Abstract: An optical system for analyzing light from a plurality of samples is provided. The optical system includes a plurality of holders adapted to have samples located therein, a collection lens, a transmission grating, and a reimaging lens. The collection lens is configured to receive and substantially collimate light from the samples. The transmission grating is configured to spectrally disperse the substantially collimated light from the collection lens. The reimaging lens is configured to receive the light from the light dispersing element and direct the light onto a light detection device. A method of optically analyzing at least one sample is also provided.

Abstract: A viewing enhancement lens (18-NAIL) which functions to increase the numerical aperture or light gathering or focusing power of viewing optics such as a microscope (26) used to view structure within a substrate such as a semiconductor wafer or chip or of imaging optics such as media recorders. The result is to increase the resolution of the system by a factor of between n, and n2, where n is the index of retraction of the lens substrate.

Abstract: An objective with lenses made of two different crystals, in particular CaF2 and BaF2 is particularly suitable as a refractive projection objective for microlithography at 157 nm. Such projection objectives for 193/248 nm with quartz glass and achromatization with CaF2 are compaction-resistant with BaF2. Microlithography projection exposure equipment in the 100-200 nm wavelength region include other fluorides and partially catadioptric objectives.

Abstract: Partial objective for illumination of an image field in an illuminating device of a microlithographic projection exposure apparatus, arranged between a aperture plane and an image plane. The partial objective comprises a first lens group and a second lens group with a lens with a first aspheric lens surface. The second lens group has at least a first lens with negative refractive power and at least a second lens with positive refractive power. The maximum field height Yimmax within the image field is at least 40 mm; the image-side numerical aperture is at least 0.15. The distribution of the chief ray angles PF over the field heights Yim within the image field is given by a pupil function PF(Yim), which consists of a linear contribution c1·Yim and a non-linear contribution PFNL(Yim), the non-linear contribution PFNL(Yim) being at least +15 mrad for the maximum positive field height Yimmax.

Abstract: In performing an light emitting operation using a plurality of semiconductor light-emitting devices, these semiconductor light-emitting devices are lighted up such that the driving current is lessened and the life time of the devices is prevented from being shortened and lights can be emitted to a remote site without reducing an amount of lights. Semiconductor laser devices 23a to 23c, which emit lights through independent lenses 25a to 25c, are connected in series to each other and connected to a signal generating circuit 24, serving as a power supply, so as to perform pulse lighting, whereby making it possible to light up three semiconductor laser devices simultaneously at a driving current corresponding to one semiconductor laser device. A package of semiconductor laser devices 23a to 23c comprises three lead terminals, and an electrical connection to two lead terminals, which are electrically insulated from a metallic base, is established.

Abstract: A bi-convex solid immersion lens is disclosed. Unlike conventional plano-convex solid immersion lenses having a flat bottom surface, the disclosed lens has a convex bottom surface. The radius of curvature of the bottom surface is smaller than that of the object to be inspected. This construction allows for a more accurate determination of the location of the inspected feature, and enhances coupling of light between the immersion lens and the inspected object. The disclosed lens is particularly useful for use in microscope for inspection of semiconductor devices and, especially flip-chip (or chip scale) packaged devices. The immersion lens can also be incorporated in a read or read/write head of optical memory media.

Abstract: In an imaging lens made of three lens sheets, the second and third lenses from the object side are shaped substantially similar to each other, thereby reducing the manufacturing cost while improving resolution. The first lens L1 is a biconcave lens having a surface with a stronger curvature directed onto the object side. Each of the second lens L2 and third lens L3 is a biconvex lens having a surface with a stronger curvature directed onto the imaging surface side, while the second lens L2 and third lens L3 have the same form. As the second lens L2 and third lens L3 have the same form, the cost of manufacturing the imaging lens can be reduced, though being constituted by three sheets of lenses.

Abstract: The invention relates to an endoscope lens which shows only a low level of distortion even at large angles of sight and whose elements can be produced and assembled with little effort, consisting of a first lens group having negative total refractive power, of an aperture diaphragm, and of a second lens group having a positive total refractive power, whereby all lens surfaces are spherical and all lenses are made of homogeneous materials. The first lens group contains at least one positive lens which is primarily arranged in the beam direction, and at least one negative lens, whereby the negative lenses in the first lens group are biconcave or plano-concave lenses. The invention also relates to an endoscope equipped with a lens of this type.

Abstract: A microscopic lens, of size approximate 1 micron is used for its optical characteristics.

Abstract: A microlithographic projection exposure arrangement has an off-axis field and has a catoptric or catadioptric projection objective (P). In this arrangement, the illumination system (ILL) is made as small as possible in that a lateral offset (&Dgr;y) of the optical axes (OAI, OAP) is introduced relative to each other. A corrective element (AE) is arranged off-axis and functions to adapt the telecentry.

Abstract: A bi-convex solid immersion lens is disclosed. Unlike conventional plano-convex solid immersion lenses having a flat bottom surface, the disclosed lens has a convex bottom surface. The radius of curvature of the bottom surface is smaller than that of the object to be inspected. This construction allows for a more accurate determination of the location of the inspected feature, and enhances coupling of light between the immersion lens and the inspected object. The disclosed lens is particularly useful for use in microscope for inspection of semiconductor devices and, especially flip-chip (or chip scale) packaged devices. The immersion lens can also be incorporated in a read or read/write head of optical memory media.

Abstract: An endoscope system in which a normal observation image and a near observation image are photographed by a solid-state image sensor upon operation of a focus adjustment device for changing a focal length and a working distance satisfies: WDWide>WDtele fwide≧ftele where fwide is a focal length in a normal observation mode, WDwide is a working distance in the normal observation mode, ftele is a focal length in a near observation mode, and WDtele is a working distance in the near observation mode. Whereby, the endoscope system is provided with a wide depth of field so as to allow even a person without considerable skills to easily manipulate the system in the magnifying observation mode, is able to improve accuracy of diagnosis information by enhancing seeming resolution of the magnified information, and is able to improve accuracy of diagnosis by facilitating discussion among a plurality of medical doctors.

Abstract: An objective lens assembly for use in an image intensifier over the 0.6 to 0.9 micron spectral bandwidth resulting in a F# within a range of 1.0 to 1.5 and a field of view within the range of 35 to 45 degrees. The assembly includes an air-spaced doublet, a right angle fold prism for bending the optical axis 90 degrees to a reoriented optical axis, two lens subassemblies, and a field flattening lens.

Abstract: A low magnification liquid immersion objective lens system uses an immersion liquid having a refractive index for the d-line within a range defined by a condition (1) shown below, and has a magnification &bgr; and a working distance WDL which satisfy the following conditions (2) and (3): 1.34≦ND≦1.80  (1) &bgr;≦15  (2) WDL≦0.35 mm.

Abstract: In an imaging lens made of three lens sheets, the second and third lenses from the object side are shaped substantially similar to each other, thereby reducing the manufacturing cost while improving resolution. The first lens L1 is a biconcave lens having a surface with a stronger curvature directed onto the object side. Each of the second lens L2 and third lens L3 is a biconvex lens having a surface with a stronger curvature directed onto the imaging surface side, while the second lens L2 and third lens L3 have the same form. As the second lens L2 and third lens L3 have the same form, the cost of manufacturing the imaging lens can be reduced, though being constituted by three sheets of lenses.

Abstract: A liquid immersion type microscope objective lens includes, in sequence from an object side, a first lens group containing meniscus lenses with their concave surfaces toward an object and having positive refractive power, a second lens group having the positive refractive power, and a third lens group having negative refractive power, wherein a distance from an object surface to a first lens surface of said first lens group is larger than a focal length f of a whole objective lens system, and a radius of curvature r1 of the first lens surface in relation to the focal length f satisfies a relation such as 4<|r1/f|<7.

Abstract: An microscope objective lens system comprises a first lens unit including a plurality of cemented lens components and converging light coming from an object, a second lens unit including a negative lens component having a strong concave surface on the image side, and a third lens unit including a cemented doublet composed of a negative lens element having a concave surface on the object side and a positive lens element, wherein the objective lens system satisfies the following conditions:

Abstract: A liquid immersion type microscope objective lens comprises a first lens group G1 having a positive refracting power, a second lens group G2 having a positive refracting power, a third lens group G3 having a negative refracting power, a fourth lens group G4, and a fifth lens group G5, in order from an object side. The first lens group G1 has a cemented lens which comprises a plano-convex lens with the plane surface facing the object side and a meniscus lens with the concave surface facing the object side cemented together, and a positive meniscus lens with the concave surface facing the object side. The second lens group G2 has a plurality of cemented surfaces having a negative refracting power. The third lens group G3 has a cemented lens which comprises a negative lens, a positive lens, and a negative lens cemented together.

Abstract: An immersion microscope objective lens comprises a first lens group G1 having a positive refracting power, a second lens group G2 having a positive refracting power and a third lens group G3 having a negative refracting power in the order from the object side. The first lens group G1 has a first cemented lens consisting of a plano-convex lens with the flat surface facing the object side and a meniscus lens with the convex lens facing the image side cemented together, a positive lens with the surface having a greater refractive power facing the image side, and a second cemented lens consisting of a negative lens and a positive lens cemented together, in the order from the object side. The second lens group G2 has a cemented lens consisting of a negative lens and a positive lens cemented together. The refractive index n12 of the meniscus lens in the first lens group G1 with respect to the d-line satisfies the following condition: n12>1.9.

Abstract: An illumination optical system for a microscope is provided wherein the illumination state can be successively changed between Koehler illumination and critical illumination while ensuring one or more conditions are satisfied so that the image of the light source illuminates an appropriately large region of the field of view of the microscope during critical illumination. Preferably, no cemented lens elements are used so that degradation of the cement caused by ultraviolet light sources is avoided, thereby enabling an appropriate illumination type to be provided at will and without degradation of the optical components of the illumination optical system over time.

Abstract: A flow cytometry lens system features a low (<1.55) refractive index, near hemispheric plano-convex lens nearest a cytometry flow cell with the planar surface on the object side of the system and a convex surface with a radius of curvature in a range from 3.5 to 5.5 mm, followed by a pair of positive meniscus lenses having the concave sides facing the object side, with the surfaces of the second meniscus lens less sharply curved than the corresponding surfaces of the first meniscus lens, which in turn is followed by a positive doublet lens. The lens elements are optimized for providing a working distance of at least 1.75 mm, a field of view of at least 400 &mgr;m, a numerical aperture of at least 1.19 and a lens magnification in excess of 10.

Abstract: An objective lens includes a first lens unit constructed with a plurality of single lenses, having a negative power as a whole, and a second lens unit constructed with a plurality of single lenses, arranged on the object side of the first lens unit.

Abstract: A high-aperture objective comprising a first lens L1 with positive refractive power f1 and a second lens L2 with negative refractive power f2, wherein the focal length ratio between the two lenses is in the range of −0.4<(f1/f2)<−0.1 and the total refractive power 1/f1+1/f2 is greater than zero, two positive lenses L3, L4 whose ratio diameter d3, d4 to focal length f3, f4 satisfies the condition greater than 0.3 and less than 0.6:0.3<d3/f3<0.6, 0.3<d4/f4<0.6, a negative lens L5 and a collective lens L6, wherein the negative lens faces the front group and the focal length ratio of L5 and L6 f5/f6 is between −0.5 and −2:−0.5<f5/f6<−2.

Abstract: A microscope objective lens having a large aperture and yielding satisfactorily corrected, flat images. The microscope objective lens includes, in order from the object side, a first lens group G1 having an overall positive refractive power and a second lens group G2. The second lens group G2 includes plural Gauss lens sets G2A, G2C. Each Gauss lens set is formed of, in order from the object side, a meniscus-shaped optical element with its concave surface on the image side, and a meniscus-shaped optical element with its concave surface on the object side. Preferably, each of these meniscus-shaped optical elements is formed of two lens elements that are cemented together. Prescribed conditions are set forth to favorably correct various aberrations.

Abstract: A high-aperture objective comprising a first lens L1 with positive refractive power f1 and a second lens L2 with negative refractive power f2, wherein the focal length ratio between the two lenses is in the range of −0.4<(f1/f2)<−0.1 and the total refractive power 1/f1+1/f2 is greater than zero, two positive lenses L3, L4 whose ratio diameter d3, d4 to focal length f3, f4 satisfies the condition greater than 0.3 and less than 0.6: 0.3<d3/f3<0.6, 0.3<d4/f4<0.6, a negative lens L5 and a collective lens L6, wherein the negative lens faces the front group and the focal length ratio of L5 and L6 f5/f6 is between −0.5 and −2: −0.5<f5/f6<−2.

Abstract: An immersion microscope objective lens comprises a first lens group G1 having a positive refracting power, a second lens group G2 having a positive refracting power and a third lens group G3 having a negative refracting power in the order from the object side. The first lens group G1 has a first cemented lens consisting of a plano-convex lens with the flat surface facing the object side and a meniscus lens with the convex lens facing the image side cemented together, a positive lens with the surface having a greater refractive power facing the image side, and a second cemented lens consisting of a negative lens and a positive lens cemented together, in the order from the object side. The second lens group G2 has a cemented lens consisting of a negative lens and a positive lens cemented together.

Abstract: A microscope objective lens of the present having, in the order from the object side, a first lens group, a second lens group and a third lens group. The first lens group comprises a meniscus lens with its concave surface facing the object side and a plurality of cemented lenses, and has a positive refractive power on the whole. The second lens group comprises a plurality of cemented lenses and has a positive refractive power on the whole. The third lens group comprises a plurality of cemented lenses and having a negative refractive power on the whole, and fulfills the following conditions (1) to (3): 2.5<f1/f<5  (1) 30<f2/f<70  (2) 15<|f3/f|<30  (3) where f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, and f is the focal length of the whole microscope objective lens system.

Abstract: A large numerical aperture objective lens is disclosed having three lens groups. In order from the object side, these lens groups include: a first lens group of positive refractive power that is formed of two positive lens elements and an achromatic set of paired lens elements formed of a lens element of negative refractive power and a lens element of positive refractive power, respectively; a second lens group of negative refractive power; and a third lens group of positive refractive power, with the surface of the third lens group nearest the object side being convex. Specified conditions are satisfied in order to provide a compact, large numerical aperture objective lens having its aberrations favorably corrected as well as to correct for shifts of focus caused by expansion/contraction of the lens barrel with changes in temperature.

Abstract: A REMA objective is realized by introduction of a few (1 to 5 units) aspherical surfaces of high-quality correction with a low number of lenses (no more than 10), and low path in glass (maximum 25% to 30%) of the object-reticle distance, thus enhancing efficiency.

Abstract: An objective lens for a microscope of the invention comprises, in order from an object side: a first lens group comprising a meniscus positive lens with a concave surface facing the object; a second lens group including a cemented lens and having a positive refractive power; a third lens group including a cemented lens and having a positive refractive power; a fourth lens group comprising a cemented lens; and a fifth lens group comprising a cemented lens.

Abstract: A microscope objective lens of the present having, in the order from the object side, a first lens group, a second lens group and a third lens group. The first lens group comprises a meniscus lens with its concave surface facing the object side and a plurality of cemented lenses, and has a positive refractive power on the whole. The second lens group comprises a plurality of cemented lenses and has a positive refractive power on the whole.

Abstract: An objective lens for endoscope comprises, successively from an object side, a first lens group having a negative refracting power, a second lens group having a positive refracting power, a third lens group having a negative refracting power, and a fourth lens group having a positive refracting power; wherein the third lens group and one of the second and fourth lens groups are movable along an optical axis. The objective lens further satisfies the following conditional expressions: 2.0<&bgr;1T/&bgr;1W<10.0 1.2<fT/fw where &bgr;1T is the magnification of the first lens group at the telephoto end; &bgr;1W is the magnification of the first lens group at the wide end; fT is the focal length of the whole lens at the telephoto end; and fW is the focal length of the whole lens at the wide end.

Abstract: A microscope objective lens having a large aperture and yielding satisfactorily corrected, flat images. The microscope objective lens includes, in order from the object side, a first lens group G1 having an overall positive refractive power and a second lens group G2. The second lens group G2 includes plural Gauss lens sets G2A, G2C. Each Gauss lens set is formed of, in order from the object side, a meniscus-shaped optical element with its concave surface on the image side, and a meniscus-shaped optical element with its concave surface on the object side. Preferably, each of these meniscus-shaped optical elements is formed of two lens elements that are cemented together. Prescribed conditions are set forth to favorably correct various aberrations.

Abstract: A microscope system has an objective unit including an objective lens, an objective holding device for holding the objective lens so that the objective lens can be spatially moved, at least one actuator for driving the objective lens, and an outer frame member for integrally supporting the objective lens, the objective holding device, and the actuator. Thus, an optical apparatus which is small in size, low in cost, and high in resolution can be obtained.

Abstract: A microscope objective lens is constructed with fixed lens units having a numerical aperture NA which is 0.6≦NA≦<0.8 and a magnification &bgr; which is 40≦&bgr;≦63, to observe a sample placed on a sample holding member and covered with a protective transparent member having a thickness t which is 0.1 mm<t<0.15 mm.

Abstract: A projection optical system of the present invention has a first lens group G1 being positive, a second lens group G2 being negative, a third lens group G3 being positive, a fourth lens group G4 being negative, a fifth lens group G5 being positive, and a sixth lens group G6 being positive in the named order from the first object toward the second object, in which the second lens group G2 comprises an intermediate lens group G2M between a negative front lens L2F and a negative rear lens L2R and in which the intermediate lens group G2M is arranged to comprise at least a first positive lens being positive, a second lens being negative, a third lens being negative, and a fourth lens being negative in the named order from the first object toward the second object.