Industrial Technology Research Institute

Hung-Te Lee

Chen-Chin Cheng

Mark O Freeman

Yi-Yen Laio

An improved zoom lens constitutes a plurality of lens groups of different focal length. Through adjusting the position of the lens groups, different zooming ratio may be obtained. Higher image resolution and lower cost may also be achieved through using different lens material. The lens groups have respectively focal length combination of positive, negative, positive and positive. The second and fourth lens groups are movable for obtaining high quality image.

Zoom lens

An optical pickup device including a lighting source, a condensing apparatus, a diffracting means, and a light detector. The light source generates and emits a light beam to the diffracting means. The diffracting means includes a center region and an outer region which encloses the center region. As the light travels from the light source towards the optical storage medium the main zero-order beam which reads the information on the disk encounters only the center region of the diffracting means while the two sub-beams used for track following are created as +1 and -1 diffraction orders from the outer region of the diffracting means. The three beams reflected from the recording medium all pass through the center region of the diffracting means and are diffracted in the direction of the detector therefrom. The light detector consists of multiple detector elements which convert the light that shines upon them after reflection from the recording medium into electronic signals containing the information that was recorded on the medium.

Single surface diffractive element for optical pickup heads

A zoom lens system consists of four lens elements arranged in two groups. Counting from the object side, the first two elements form a front lens group with positive refracting power and the last two elements form a rear lens group with negative refracting power. An airspace is reserved between the front lens group and the rear lens group and it is made variable for zooming. The first lens element in the front lens group is a negative lens element and has its concave lens surface directed toward the object side. Both the two lens elements in the rear lens group are negative lens element. In the lens composition, both the front lens group and the rear lens group at least include an aspherical lens surface respectively for aberration correction.

Compact zoom lens system

A zoom lens system is arranged in three lens groups, in the order from object side to image plane side, that the first lens group has negative refractive power, the second lens group has positive refractive power, and the third lens group has negative refractive power. During zooming operation from wide angle position to telephoto position, the three lens groups vary the separations therebetween and together move toward the object side of the lens system. The first lens group of the lens system is composed of a negative lens element and a positive lens element.

Zoom lens system

A lens system comprising a positive power lens assembly and a negative power lens assembly, in which the positive power lens assembly includes a cemented doublet and a two-surface aspheric lens. The present invention discloses a zoom lens with a 2.57.times.zoom ratio.

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Taipei, Taiwan

Hung-Te Lee