JPS643832A - Optical head device - Google Patents

Optical head device

Info

Publication number
JPS643832A
JPS643832A JP62158044A JP15804487A JPS643832A JP S643832 A JPS643832 A JP S643832A JP 62158044 A JP62158044 A JP 62158044A JP 15804487 A JP15804487 A JP 15804487A JP S643832 A JPS643832 A JP S643832A
Authority
JP
Japan
Prior art keywords
information
line
diffracted light
line direction
elliptic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP62158044A
Other languages
Japanese (ja)
Other versions
JP2542387B2 (en
Inventor
Hidekazu Tode
Shinsuke Shikama
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP62158044A priority Critical patent/JP2542387B2/en
Publication of JPS643832A publication Critical patent/JPS643832A/en
Application granted granted Critical
Publication of JP2542387B2 publication Critical patent/JP2542387B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Landscapes

  • Optical Head (AREA)

Abstract

PURPOSE:To improve the SN ratio of a playback signal by forming a holographic element in such a grating shape that diffracted light forms an elliptic convergence spot which is thin and long in the line direction of information tracks on an information recording medium. CONSTITUTION:The grating shape of the holographic element 6 is so formed that the grating period decreases gradually in the direction (y) of information tracks about A as a line of symmetry. Unnecessary diffracted light which is astigmatic luminous flux equivalent to reflected luminous flux 7 converged by a condenser lens 7 forms a vertical focus line in the line direction of the information track 5 at a position (t') conjugate to a position (t) as the focus of the line direction of the information track 5, thereby projecting the elliptic convergence spot 11. Consequently, information can not be read with the unnecessary diffracted light and even if the light is photodetected by a photodetector 8, it does not cause the generation of a noise in an original signal.
JP62158044A 1987-06-25 1987-06-25 Optical head device Expired - Lifetime JP2542387B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP62158044A JP2542387B2 (en) 1987-06-25 1987-06-25 Optical head device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62158044A JP2542387B2 (en) 1987-06-25 1987-06-25 Optical head device

Publications (2)

Publication Number Publication Date
JPS643832A true JPS643832A (en) 1989-01-09
JP2542387B2 JP2542387B2 (en) 1996-10-09

Family

ID=15663064

Family Applications (1)

Application Number Title Priority Date Filing Date
JP62158044A Expired - Lifetime JP2542387B2 (en) 1987-06-25 1987-06-25 Optical head device

Country Status (1)

Country Link
JP (1) JP2542387B2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2794114B2 (en) 1988-09-06 1998-09-03 京セラ株式会社 Optical information reproducing device

Also Published As

Publication number Publication date
JP2542387B2 (en) 1996-10-09

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Legal Events

Date Code Title Description
EXPY Cancellation because of completion of term