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.

Disclosed are various embodiments regarding a head-mounted device. According to an embodiment, a mount device comprises: a housing comprising a front surface, a rear surface that can be mounted on a head, and a side surface surrounding the front surface and the rear surface; a coupling portion can be disposed in housing, and can be configured to be coupled so as to slope an external electronic device at a designated angle with regard to the side surface; a prism comprising a first surface capable of facing, at the designated angle, at least a part of a display included in the external electronic device that can be coupled to the coupling portion, a second surface capable of changing (through total reflection) the direction of light that is incident from the display through the first surface, and a third surface capable of emitting the light, the direction of which has changed; a mirror arranged between at least a part of the side surface and the third surface; and a splitter arranged between the mirror and the third surface to be capable of transmitting at least a part of light emitted through the third surface and changing the direction of the light, which is transmitted and then reflected by the mirror, to a direction corresponding to the rear surface. Various other embodiments are possible.

Disclosed are various embodiments regarding a head-mounted device. According to an embodiment, a mount device comprises: a housing comprising a front surface, a rear surface that can be mounted on a head, and a side surface surrounding the front surface and the rear surface; a coupling portion can be disposed in housing, and can be configured to be coupled so as to slope an external electronic device at a designated angle with regard to the side surface; a prism comprising a first surface capable of facing, at the designated angle, at least a part of a display included in the external electronic device that can be coupled to the coupling portion, a second surface capable of changing (through total reflection) the direction of light that is incident from the display through the first surface, and a third surface capable of emitting the light, the direction of which has changed; a mirror arranged between at least a part of the side surface and the third surface; and a splitter arranged between the mirror and the third surface to be capable of transmitting at least a part of light emitted through the third surface and changing the direction of the light, which is transmitted and then reflected by the mirror, to a direction corresponding to the rear surface. Various other embodiments are possible.

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 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.

A vehicular interior rearview mirror assembly includes a mounting structure configured for mounting at an interior portion of a vehicle. The mounting structure includes a mounting arm that has (i) a proximal end portion and (ii) a distal end portion distal from the proximal end portion. With the mounting structure mounted at the interior portion of the vehicle, the proximal end portion of the mounting arm is attached at the interior portion of the vehicle. A motorized actuator is disposed within a mirror housing that accommodates a reflective element. The motorized actuator is electrically operable to adjust the reflective element and the mirror housing together and in tandem relative to the mounting structure to provide a desired rearward field of view to a driver of the vehicle when the vehicular interior rearview mirror assembly is mounted and operated in the vehicle.

A lens device includes a first lens module, a first light path turning module and an image sensor. The first lens module, the first light path turning module and the image sensor are sequentially arranged along a light path in which a light beam propagates. The first light path turning module is configured to change a direction in which the light beam propagates so that the light beam passes through the first lens module to form an image on the image sensor.

Described examples include an optical device, having a light source with a light source output and a light integrator having a light integrator input and a light integrator output, the light integrator input optically coupled to the light source output, and the light integrator configured to provide divergent light at the light integrator output responsive to the light at the light source output. The optical device also has projection optics with an optics input and an optics output, the projection optics configured to project output light at the optics output responsive to modulated light at the optics input, in which a focal point of the optics input matches a divergence of the modulated light and a spatial light modulator optically coupled between the light integrator output and the optics input, the spatial light modulator configured to provide the modulated light responsive to the divergent light.

Described examples include an optical device, having a light source with a light source output and a light integrator having a light integrator input and a light integrator output, the light integrator input optically coupled to the light source output, and the light integrator configured to provide divergent light at the light integrator output responsive to the light at the light source output. The optical device also has projection optics with an optics input and an optics output, the projection optics configured to project output light at the optics output responsive to modulated light at the optics input, in which a focal point of the optics input matches a divergence of the modulated light and a spatial light modulator optically coupled between the light integrator output and the optics input, the spatial light modulator configured to provide the modulated light responsive to the divergent light.

A lens device includes a first lens module, an image sensor and a first light path turning module. The first lens module includes plurality of lenses. The first light path turning module is configured to transmit a light beam passing through the first lens module to the image sensor by exactly three or four reflections. The first light path turning module includes three or four reflecting surfaces on which the reflections occur. All the reflecting surfaces are plane surfaces. The first light path turning module includes no free form surface. All the surfaces on which the light beam is reflected are plane surfaces, wherein the plane surfaces are flat and are different from freeform surfaces.