An observation optical system includes a display element and an eyepiece lens arranged on an eyepoint side of the display element. The eyepiece lens consists of a first lens having positive refractive power, a second lens having negative refractive power, and a rear side lens group including two or more lenses consecutively in order from a side closest to the display element to the eyepoint side. In a case where a half value of a longest diameter of a display region in the display element is denoted by H, and a focal length of the eyepiece lens is denoted by f, the observation optical system satisfies a conditional expression represented by 0.3<H/f<0.5.

A head-mounted display (HMD) having a line-of-sight detection function includes angle selection type transmission elements that are disposed in a finder optical path for eyes of a user, respectively, a light projecting unit and a light receiving unit for line-of-sight detection, and is configured to be capable of adjusting a direction of a finder to a detected line-of-sight direction. The angle selection type transmission elements have first to third opening portions with different directions. The first and second opening portions limit a passage direction of light in first and second regions in a finder optical path, respectively. The third opening portion is formed around a line connecting an eye point and the light receiving unit.

An objective optical system includes in order from an object side, a front unit having a positive refractive power and a rear unit. The front unit includes in order from the object side, a first lens having a negative refractive power, a second lens having a positive refractive power, and a third lens having a positive refractive power. The rear unit includes one lens or a plurality of lenses and the following conditional expression is satisfied:
|(FLag−FLaC)/FLad|<0.05  (1) where, FLad denotes a focal length for a d-line of the front unit, FLag denotes a focal length for a g-line of the front unit, and FLaC denotes a focal length for a C-line of the front unit.

In example implementations, an apparatus is provided. The apparatus includes a display, an eye barrel, an anti-reflection layer, and a lens. A first end of the eye barrel is coupled to the display. The anti-reflection layer is applied to an inner surface of the eye barrel. The lens is coupled to a second end of the eye barrel.

A device for outcoupling a portion of the radiation of an observation beam path of a binocular eyepiece for documentation or co-observation that is freely selectable at any time. For the outcoupling, a rotatable supporting unit, the axis of rotation of which is parallel to the axes of the observation beam paths, is arranged in the housing having the binocular eyepiece. Three optical elements are arranged on this supporting unit such that an outer and the middle optical element and, after rotation of the supporting unit, the middle and the other outer optical element are each located in one of the observation beam paths. Here, the two outer optical elements have a beam-splitting effect and outcouple a portion of the observation radiation into a common documentation beam path.

Techniques are described for applying an edge sealant to the edge of a multi-layer optical device. In particular, embodiments provide an apparatus that performs a precision measurement of the perimeter of an eyepiece, applying the edge sealant (e.g., polymer) based on the precision-measured perimeter, and subsequently cures the edge sealant, using ultraviolet (UV) light that is directed at the edge sealant. The curing process may be performed within a short time following the application of the edge sealant, to ensure that any wicking of the edge sealant between the layers of the eyepiece is controlled to be no greater than a particular depth tolerance. In some examples, the edge sealant is applied to the optical device prevent, or at least reduce, the leakage of light from the optical device, and also to ensure and maintain the structure of the multi-layer optical device.

A surgical microscope for generating an image of an object region includes an eyepiece and an objective conjointly defining a viewing beam path, an image capturing device and a beam path switching device for out-coupling image information. The switching device is switchable between a first switching state wherein light in the viewing beam path is split into a first component along a first beam path to the eyepiece at an intensity IT1 and a second component along a second beam path to the image capturing device at an intensity IT2 and a second switching state wherein the light in the viewing beam path is deflected into the second beam path to the image capturing device at an intensity IU. The switching device includes a beam splitter movable in and out of the viewing beam path and a deflecting element movable into and out of the viewing beam path.

An optical module comprising: at least three lens elements, wherein the lens elements collectively set a numerical aperture NA, a field height FH, and a system effective focal length EFLsys for directing the light rays between first and second planes, wherein NA, FH, and EFLsys satisfy 0<NA<0.25 and 0<FH<(0.4).Math.(EFLsys); wherein first and second adjacent lens elements having effective focal lengths EFL1 and EFL2, respectively, satisfies (1.5).Math.(EFLsys)<EFL1<3.Math.(EFLsys) and (1.5).Math.(EFLsys)<EFL2<3.Math.(EFLsys); wherein an air-distance between the first and second lens elements A.sub.12 satisfies 0<A.sub.12<EFLsys; wherein a third lens element adjacent the second lens elements opposite the first lens element and having an effective focal length EFL3 satisfies (−20).Math.EFLsys<EFL3<(−1).Math.EFLsys; and wherein an air-distance between the second and third lens elements A.sub.23 satisfies 0<A.sub.23<EFLsys.

A multichannel tunable lens system may include a review channel with a fluidic focusing device, which can adjust the focus of the channel rapidly to mitigate environmental vibrations. The review channel may generate high resolution images with reduced blur caused by vibrations or air turbulence while increasing the operating speed of the system. The review channel may include a telescope objective and eyepiece with telecentricity to generate a real image of the pupil in the fluidic focusing device. The system may also include an inspection channel to generate lower resolution images in parallel and a focus channel to determine contour information.

The invention relates to an attachment device for at least one objective lens and/or at least one eyepiece of a long-range optical device, in particular in the form of a riflescope, a telescope or a binocular, wherein the attachment device comprises at least one window, which is transparent at least in a visible spectral range, as well as at least one electrical heating device for the window.