An optical system having a viewing angle θ relative to a longitudinal axis including: a prism group to deflect incident light by reflection at first and second surfaces including prisms with mutually adjacent boundary surfaces arranged in pairs and separated by a gap, a total reflection of incident light from outside a field of view takes place at a boundary surface between a prism and a corresponding gap, the prism group has a cylindrical envelope (D), and an input-side prism is configured to have a wedge-shape with angle β and an optical path length α; an entry surface of the prism has a length L, which is a length of a line of intersection of the entry surface with a plane that is spanned by a central beam path; and the first prism meets the conditions: α<cos θ.Math.tan β.Math.D/2 and L<D/cos θ.

An optical system includes, in order from an object side to an image side, a first lens unit having a negative refractive power, a first reflective member, a second lens unit including an aperture diaphragm and having a positive refractive power, a second reflective member, and a third lens unit having a positive refractive power. Following inequalities are satisfied:

−1.27<(f1/f)/Npr<−0.70

0.60<f2/f3<1.60

where f represents a focal length of the optical system, f1 represents a focal length of the first lens unit, f2 represents a focal length of the second lens unit, f3 represents a focal length of the third lens unit, and NPr represents a refractive index of the first reflective member.

An anti-vibration optical system is an observation optical system including, in sequence from an object side, an objective optical system, an erecting prism, and an ocular optical system, wherein: in sequence from the object side, the objective optical system includes a first lens group having a positive refracting power and a second lens group having a negative refracting power; in sequence from the object side, the second lens group comprises a positive lens group having a positive refracting power and a negative lens group having a negative refracting power; and an image position can be changed by the negative lens group of the second lens group being displaced in a direction orthogonal to an optical axis.

A deflection prism assembly for an endoscope having a lateral viewing direction, the deflection prism assembly including: a prism holder; and a deflection prism accommodated in the prism holder; wherein the deflection prism has a light outlet surface and an opposite light inlet surface arranged obliquely to the light outlet surface, the deflection prism further having a lateral surface extending between the light inlet surface and the light outlet surface; and the prism holder accommodates the deflection prism such that the prism holder surrounds less than all regions of the lateral surface of the deflection prism.

An eyepiece optical system includes a focal-plane plate, having a positive refractive power on one side and a diffusion surface on the other side thereof; a reflector which reflects light rays of an object image, formed on the diffusion surface, a predetermined number of times; an optical lens group, by which the object image is observed, in that order along an optical path from the object side to the viewing side; and a condenser lens element, having a positive refractive power, provided between the focal-plane plate and the reflector, the condenser lens element having an aspherical surface formed on at least one side thereof. At least one of the aspherical surface of the condenser lens element has a profile, when viewed macroscopically, such that the positive refractive power thereof increasingly weakens with respect to a direction away from the optical axis.

A distance detection device is provided, including a calculating unit that calculates a distance to a detection target using a length of time until floodlighted light is received by a light-receiving unit; a first detecting unit that detects whether detection target changing operation is being performed; a second detecting unit that detects variation in the distance calculated by the calculating unit; a shake correcting optical system that is driven based on a shake detection result and through which the floodlighted light passes; and a control unit that controls driving of the shake correcting optical system using an output from the first detecting unit and an output from the second detecting unit.

A composite prism for multi-functional telescopes, and binocular telescopic optical system thereof. The composite prism comprises a first half-pentaprism (2), a roof prism (3), and a second half-pentaprism (4). Longer right-angled surfaces of the first half-pentaprism (2) and second half-pentaprism (4) are cemented onto a bottom surface of the roof prism (3). A light incident plane of the roof prism (3) and a light emission plane thereof share the same one and are parallel to a roof edge of the roof prism (3), such that a light incident axis of the composite prism is parallel to a light emission axis thereof. A binocular telescopic optical path system comprises an objective lens (1), the composite prism, a reticle lens (5), and an eyepiece (6), and has functions of viewing, sighting, laser emitting and receiving, and display.

A stereoscopic optical system includes two parallel optical systems that each include, in order from an object side to an image side, a front unit having a negative refractive power, an intermediate unit having two reflective surfaces, and a rear unit. A distance between optical axes of rear units is smaller than that between optical axes of front units in the two optical systems due to bending of an optical path by the two reflective surfaces. At least one of the intermediate unit and the rear unit has a positive refractive power. The front unit includes, in order from the object side to the image side, a first subunit consisting of one or more negative lenses disposed on the object side of a positive lens closest to an object in the front unit, and a second subunit having a positive power. A predetermined condition is satisfied.

Disclosed is an optical scope including an objective lens, an eyepiece lens, and a reticle, wherein a field lens having negative power is disposed in at least one of a front and a back of the reticle disposed on an image formation surface of the objective lens to increase eye-relief.

A field-of-view transformation structure of a head-mounted magnifying-glass comprises: a wearing-piece, a supporting-assembly, a first pivoting-portion, a magnifying-glass main-body, a first prism main-body, and a second prism main-body; wherein the supporting-assembly is set with the wearing-piece, the first pivoting-portion is defined on the supporting-assembly, the magnifying-glass main-body and the first pivoting-portion are pivotally set mutually, a first facing-eye-surface is defined on the first prism main-body corresponding to the magnifying-glass main-body, and a second facing-eye-surface is defined on a offset position of the magnifying-glass main-body; thus, the user can wear the wearing-piece, when wanting using the first prism main-body to watch, the magnifying-glass main-body can be flipped upwards; or, the user can directly view the second facing-eye-surface to simultaneously watch other parts of the patient when watching the magnifying-glass main-body. Besides the magnified field-of-view is bigger than the conventional technology, it also has the advantage of wide-angle field-of-view.