Abstract: A combination of an optical element and an antireflection film, the optical element being provided with a microlens array and configured to diverge a light beam, the maximum angle of a diverged ray to a reference axis being D, wherein in each microlens Z / P ? 0 . 8 is satisfied, where Z represents distance between the vertex and the bottom and P represents the diameter of the smallest circle enclosing the bottom and the antireflection film being designed such that { T ? ( 0 ) / T ? ( D ) } / { T ? ( 0 ) / T ? ( D ) } ? 0 . 8 ? 5 is satisfied, where T(0) and T(D) respectively represent transmittance of the film formed on a substrate made of the material of the optical element for incident rays at 0 and D, and T?(0) and T?(D) respectively represent transmittance of the substrate without an antireflection film for incident rays at 0 and D, wherein the combination is configured so as to realize a target intensity distribution of diverged rays.

Abstract: An imaging optical system wherein the number of lenses is three to seven, one to four lenses, each of which is an aspheric lens in which radius of curvature of each of both surfaces is infinity in the paraxial region and which has a power of the third-order aberration region in the peripheral area are provided, the first lens from the object side is a negative lens or the aspheric lens, the relationship 0 . 1 ? 8 < ( ? i = 1 i = n ? "\[LeftBracketingBar]" 1 f i ? "\[RightBracketingBar]" ) · f n < 0 . 9 is satisfied where i represents a natural number, fi represents focal length of the i-th lens from the object side, f represents focal length of the whole system and n represents the number of the lenses, and the relationship 40°<HFOV<80° is satisfied where HFOV represents angle that the principal ray of bundle of rays that enters the imaging optical system and reaches the maximum value of image height forms with the optical axis.

Abstract: A method for producing a plastic element provided with fine surface roughness is provided. In the method, etching of a surface of the plastic element is performed separately in a first step and in a second step, in the first step, fine roughness having a predetermined average value of pitch in the range from 0.05 to 1 micrometer is generated on the surface through reactive ion etching in an atmosphere of a first gas; and in the second step, an average value of depth of the fine roughness generated in the first step is adjusted to a predetermined value in the range from 0.15 to 1.5 micrometers while the predetermined average value of pitch is substantially maintained through reactive ion etching in an atmosphere of a second gas, reactivity to the plastic element of the second gas being lower than reactivity to the plastic element of the first gas.

Abstract: A press molding method of a glass optical element using a mold, the method including plural steps with pressurizing, in each of which load is imposed on a piece of glass material at a temperature above the glass transition temperature, and a step without pressurizing between two steps with pressurizing, wherein in a step without pressurizing between a first step with pressurizing and a second step with pressurizing, the second step with pressurizing being the next step with pressurizing after the first step with pressurizing, the temperature of the mold is reduced by 50 degrees centigrade or greater with respect to the temperature of the mold in the first step with pressurizing and then the mold is heated before the start of the second step with pressurizing.

Abstract: An optical unit of plastic provided with a surface for incident light and a surface for outgoing light, wherein the surface for incident light is designed to face a light source and the surface for outgoing light is designed to face an element for receiving light so as to optically connect the light source and the element for receiving light and wherein the optical unit is so shaped that light that comes from the light source and is incident on the surface for incident light forms a first image of the light source within the optical unit and a second image of the light source after having gone through the surface for outgoing light and the optical unit is provided with an attenuating portion for attenuating the quantity of light passing therethrough in the vicinity of the position where the first image is formed.

Abstract: A method of producing a diffraction grating of borosilicate glass or barium borosilicate glass, the method comprising the steps of forming a grating on a surface of a silicon wafer the grating through the Bosch process; forming an oxide film on a surface of the grating by heating and exposure to water vapor of the silicon wafer; removing the oxide film using hydrofluoric acid; making the surface provided with the grating of the silicon wafer and a surface of a glass plate undergo anodic bonding; heating the silicon wafer and the glass plate bonded to each other; polishing a surface opposite to the boded surface of the silicon wafer and a surface opposite to the boded surface of the glass plate; and removing silicon from the glass plate by selective etching using xenon difluoride.

Abstract: A method for manufacturing optical scanning systems by which plural optical scanning systems with different effective scanning widths can be manufactured by changing a polygon mirror alone is provided. The method includes the steps of designing a first scanning optical system using a first polygon mirror corresponding to a first value of effective scanning width; designing a second scanning optical system provided with a second polygon mirror corresponding to a second value of effective scanning width, the second value being smaller than the first value, wherein a reference point of deflection is located at the position of the reference point of deflection of the first scanning optical system; and adjusting a size and a position of the scanning lens so as to adjust a lateral magnification in a cross section in the sub-scanning direction of the imaging optical system.

Abstract: A method of producing a mold for a microlens array with a cutting tool rotating around a rotation axis, microlenses having the substantially same shapes. A z-axis of an (x, y, z) coordinate system is in the direction of the central axis of a surface of the mold. The method includes the steps of cutting a surface of the mold while each of angle ? between the rotation axis of the cutting tool and a straight line passing through a point on the rotation axis and parallel to the z-axis and angle ? of a plane containing the rotation axis and the straight line around the straight line is kept constant; and cutting the plural surfaces while the values of angle ? and angle ? are determined such that a variance of the values of at least one of angle ? and angle ? is greater than a predetermined value.

Abstract: A light guiding apparatus comprising: a light guiding substrate; a light receiving unit including first and second units provided on a surface of the substrate, the first and second units transmitting received rays along first and second paths in the substrate as first and second light beams, respectively; a first direction changing unit for the first light beam; a second direction changing unit for the second light beam; and a light emitting unit receiving the first and the second light beams, combining the beams for emission and provided on the surface, wherein on the surface the center of the minimum circle encompassing the first unit is located farther away from the light emitting unit than the center of the minimum circle encompassing the second unit and the first path runs through the portion of the substrate on which the second unit is provided.

Abstract: The diffusor has a microlens array including microlenses with the bases placed on a plane. Concerning a curved surface of each microlens, the following expressions are satisfied, where in a cross section perpendicular to the plane and containing a straight line passing through the projection point onto the plane of the vertex and maximizing a distance between two points of the straight line on the periphery of the base, coordinate along the straight line, coordinate of the curved surface of the microlens in the direction perpendicular to the plane, the maximum value of the first derivative of z? with respect to x?, the absolute value of the second derivative of z? with respect to x? at x? coordinate of the projection point and the absolute value at x? coordinate of an end of the straight line are represented respectively by x?, z?, d, D0 and D.

Abstract: A mold machining method using an endmill, the contour of a cross section of the mold being concave and continuous in an area, a ratio of the maximum to the minimum of radius of curvature of the contour of a portion of the area (a first area) being 2 or greater, and a blade of the endmill having a second area where the contour of a cross section is similar to the contour of the first area, the method comprising the steps of determining a spiral path of the endmill such that each point of the first area is machined by a portion of the second area, corresponding to said each point in the similarity, and a radial interval between the spiral tool path is maximized while keeping surface roughness of the machined mold at or below a predetermined value; and machining the mold along the path.

Abstract: A method for manufacturing a mold for a retroreflective element, the mold having plural polygonal faces having a common vertex, the method including the steps of: roughing of a polygonal face in which cutting is carried out such that a predetermined cutting amount in a finishing process is left with respect to a desired shape; and finishing of the polygonal face in which a blade portion is made to move relatively towards the vertex while an angle of relief of the blade portion is kept within 1 degree so as to carry out cutting of the predetermined cutting amount, wherein a depth of cut for each one-time cutting operation is 2 micrometers or smaller, and the movement of the blade portion is a combination of a motion towards the vertex and an oscillation.

Abstract: A method for illumination of an object to be observed to be observed and the background, the method comprising the steps of: obtaining a relationship between wavelength and spectral radiance of the object while the object and the background are illuminated by a first light source that emits light that has a continuous spectrum in the wavelength range from 380 nanometers and 780 nanometers, and determining a value of representative wavelength that corresponds to a maximum value of the spectral radiance of the object plotted against wavelength or values of representative wavelength that correspond to maximum values of the spectral radiance of the object plotted against wavelength; determining a value or values of comparative wavelength; and illuminating the object and the background with light of the value or values of representative wavelength and light of the value or values of comparative wavelength.

Abstract: An imaging optical system wherein the number of lenses is three to seven, one to four lenses, each of which is an aspheric lens in which radius of curvature of each of both surfaces is infinity in the paraxial region and which has a power of the third-order aberration region in the peripheral area are provided, the first lens from the object side is a negative lens or the aspheric lens, the relationship 0 . 1 ? 8 < ( ? i = 1 i = n ? "\[LeftBracketingBar]" 1 f i ? "\[RightBracketingBar]" ) · f n < 0 . 9 is satisfied where i represents a natural number, fi represents focal length of the i-th lens from the object side, f represents focal length of the whole system and n represents the number of the lenses, and the relationship 40°<HFOV<80° is satisfied where HFOV represents angle that the principal ray of bundle of rays that enters the imaging optical system and reaches the maximum value of image height forms with the optical axis.

Abstract: A method for manufacturing fine surface roughness having an average pitch of 50 nanometers to 5 micrometers on a quartz glass substrate without preparing a mask prior to an etching process, the method comprising the steps of: making the quartz glass substrate undergo ion etching with argon gas in an ion etching apparatus, in which the quartz glass substrate is placed on a first electrode, the first electrode is connected to a high frequency power source and a second electrode is grounded; and making the quartz glass substrate undergo reactive ion etching with trifluoromethane (CHF3) gas or a mixed gas of trifluoromethane (CHF3) and oxygen in the ion etching apparatus in which the quartz glass substrate is placed on the first electrode, the first electrode is connected to the high frequency power source and the second electrode is grounded.

Abstract: A lens for headlamps of vehicles provided with a diffraction grating on a surface, wherein a phase function of the diffraction grating is represented by ? ? ( r ) = ? i = 1 N ? ? ? 2 ? i ? r 2 ? i where r represents distance from the central axis of the lens, and the relationship |?2|·(0.3R)2<|?4|·(0.3R)4 is satisfied where R represents effective radius of the lens, and wherein a second derivative of the phase function has at least one extreme value and at least one point of inflection where r is greater than 30% of R, a difference in spherical aberration between the maximum value and the minimum value at any value of r in 0?r?R is equal to or less than the longitudinal chromatic aberration for visible light, the diffraction grating is at least partially on the surface where r is greater than 30%, and the relationship 1 < ? ? ? ( R ) R 2 ? < 10 is satisfied.

Abstract: A method for manufacturing optical scanning systems by which plural optical scanning systems with different effective scanning widths can be manufactured by changing a polygon mirror alone is provided. The method includes the steps of designing a first scanning optical system using a first polygon mirror corresponding to a first value of effective scanning width; designing a second scanning optical system provided with a second polygon mirror corresponding to a second value of effective scanning width, the second value being smaller than the first value, wherein a reference point of deflection is located at the position of the reference point of deflection of the first scanning optical system; and adjusting a size and a position of the scanning lens so as to adjust a lateral magnification in a cross section in the sub-scanning direction of the imaging optical system.

Abstract: A diffusion element is configured by combining: a structure for diffusion constituted by combining periodic surface structures having multiple periods to achieve a light intensity distribution in which the light intensity is uniform at angles less than or equal to a predetermined diffusion angle ? and the light intensity is as close as possible to zero intensity at angles greater than the diffusion angle ?; and a diffractive structure having a period of 1 or more and 2 or less times of ?max, where ?max is the maximum period of the structure for diffusion.

Abstract: A diffuser provided with plural shapes obtained by translation on an xy plane of at least one of z=g(x, y) and z=?g(x, y), z=g(x, y) being a smooth function within a rectangle having sides of length of s in x direction and sides of length of t in y direction, the origin being the center of the rectangle, wherein on the sides of the rectangle, g ? ( x , y ) = 0 , ? ? g ? ( x , y ) ? x = 0 , ? ? g ? ( x , y ) ? y = 0 , ? ? 2 ? g ? ( x , y ) ? x 2 = 0 , and ? 2 ? g ? ( x , y ) ? y 2 = 0 , and wherein z=g(x, y) has a single vertex at (xv,yv) g(x,y)=h1(x)·h2(y), first derivative of z=h1(x) is continuous in ( - s 2 , s 2 ) , second derivative of z=h1(x) has a single point of discontinuity in ( - s 2 , x v ) and ? ( x v , s 2 ) , first derivative of z=h2(y) is continuous in ( - t 2 , t 2 ) , and second derivative of z=h2(y) has a single

Abstract: The optical system includes an optical element having a curvature in a first direction alone; and first and second lens array surfaces. Each of the lens array surfaces is provided with plural toroidal lens surfaces arranged in a second direction orthogonal to the first direction, the plural lens surfaces have a curvature mainly in the second direction, any lens surface on one of the lens array surfaces corresponds to one of the toroidal lens surfaces on the other, the direction of a first straight line connecting the vertexes of two toroidal lens surfaces corresponding to each other is orthogonal to the second direction, and in a cross section containing the first straight line and a second straight line that is in the second direction, one of the two toroidal lens surfaces is configured so as to form an imaging surface of the other for the object point at infinity.