A wearable image display device eliminates the need to adjust an image focus every time the device is used. The present invention includes a mounting module and a right image display module, and a left image display module. Each of the right image display module, the left image display module includes a reflective image modulation device, a lens, a light guide plate, and a plurality of half mirrors. The lens is disposed in a state eccentric to a predetermined value with respect to the reflective image modulation device. As a result, the present invention eliminates the need to adjust the image focus every time the device is used.

A GRIN optic having an optical axis (z-direction) and a GRIN profile varying in the x and y-directions, the profile having one or more discontinuities extending in the x-y direction. The discontinuities may form a non-closed shape or have a non-smooth rectilinear shape. The GRIN optic may have plane-parallel surfaces. A method of designing a GRIN optic which includes mapping discretized elements in the light output specification to array elements of a linear GRIN array elements, identifying for each array element, a base refractive index n.sub.0, a gradient magnitude α, and a gradient direction θ.sub.G capable of directing a beamlet from the light source to a corresponding location in the light output specification, and constructing a piecewise-continuous freeform GRIN profile of the GRIN optic by integrating the discrete linear GRIN array elements into a continuous refractive index profile.

An optical system includes an optical element having negative refractive power and disposed on at least one of an object side and an image side of an intersection of an optical axis and a pupil paraxial ray. The optical element is made of a glass material and satisfies a predetermined condition.

An optical system includes a first relay rod of a first material, a second relay rod of a second material, different from the first material, and a lens between the first and second relay rods.

The zoom lens includes, in order from object side to image side, a positive first lens unit (LU), a negative second LU, a positive third LU, and a rear lens group including at least one LU. The zoom lens further includes an aperture stop. A LU arranged on image side of aperture stop moves during zooming. The first LU consists of at least two positive lenses (TPL), and two negative lenses (TNL). An average partial dispersion ratio (APDR) of TNL, APDR of TPL having highest refractive powers of at least TPL, an average Abbe number (AAN) of TNL, AAN of TPL, larger one of Abbe numbers of TNL, smaller one of Abbe numbers of TPL, focal lengths of first and second LUs, a distance from an optical surface closest to object side to image plane, and a focal length of zoom lens at a telephoto end are each appropriately set.

A GRIN optic having an optical axis (z-direction) and a GRIN profile varying in the x and y-directions, the profile having one or more discontinuities extending in the x-y direction. The discontinuities may form a non-closed shape or have a non-smooth rectilinear shape. The GRIN optic may have plane-parallel surfaces. A method of designing a GRIN optic which includes mapping discretized elements in the light output specification to array elements of a linear GRIN array elements, identifying for each array element, a base refractive index n.sub.0, a gradient magnitude α, and a gradient direction θ.sub.G capable of directing a beamlet from the light source to a corresponding location in the light output specification, and constructing a piecewise-continuous freeform GRIN profile of the GRIN optic by integrating the discrete linear GRIN array elements into a continuous refractive index profile.

A zoom lens includes in order from an object side, a positive first unit, one or two second units including a negative lens unit closest to the image side, and monotonously moved to the image side for zooming to a telephoto end, one or two third units including a negative lens unit closest to the object side, and moved for zooming, and a positive fourth unit disposed closest to the image side, in which the first unit includes, in order from the object side, a negative subunit, a positive subunit moved for focusing, and a positive subunit, and a focal length of the first unit, a composite focal length at the telephoto end of the second unit, a maximum moving amount for zooming of the lens unit included in the second unit, and a maximum Abbe number of the negative lens included in the second unit are properly set.

A scanning optical system (SL) comprises a first lens group (G1) having a negative refractive power, a second lens group (G2) having a positive refractive power, and a third lens group (G3) having a negative refractive power. At least one lens included in any of the first to the third lens groups has a positive refractive power, and satisfies the conditional expression “νd1>80”. At least one lens included in any of the first to the third lens group has a negative refractive power, and satisfies the conditional expression “νd2<50”. The scanning optical system satisfies the conditional expression “h max≥18.0 [mm]”.

An optical system includes a first lens unit B1 having a positive refractive power, a second lens unit B2, and a third lens unit B3 disposed in order from an object side to an image side. The second lens unit B2 moves in focusing so that an interval between adjacent lens units among the first, second, and third lens units changes. The first lens unit B1 includes a positive lens G1p disposed closest to the object side and a negative lens G1n being a closest negative lens with respect to the object side. The optical system satisfies a predetermined condition.

An optical system (LS) Includes lenses (L22,L23) satisfying the following conditional expressions,

vdLZ<35.0, and

0.702<gFLZ+(0.00316dLZ),

where vdLZ: Abbe number of the lens with reference to d-line, and gFLZ: a partial dispersion ratio of the lens, wherein gFLZ is defined by the following expression,

gFLZ(ngLZnFLZ)/(nFLZnCLZ). wherein a refractive index of the lens with reference to g-line is ngLZ, a refractive index of the lens with reference to F-line is nFLZ, and a refractive index of the lens with reference to C-line is nCLZ.