Optical device having aperture arrays for shielding light

• US 6,069,741 A
• Filed: 03/30/1998
• Issued: 05/30/2000
• Est. Priority Date: 03/31/1997
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Osawa, Yasuhiro
• Primary Examiner(s): Ben, Loha
• Application Number:
  US09/050,116
• Time in Patent Office: 792 Days
• Field of Search: 359/618, 359/619, 359/621, 359/622, 250/363.04, 250/363.01, 313/403, 313/408
• US Class Current: 359/621
• CPC Class Codes: B41J 2/465 using masks, e.g. light-switching masks
• CPC Class Codes: G02B 5/00 Optical elements other than lenses light guides G02B6/00; optical logic elements G02F3/00
• CPC Class Codes: H04N 1/03 with photodetectors arranged in a substantially linear array
• CPC Class Codes: H04N 1/0306 using a plurality of optical elements arrayed in the main scan direction, e.g. an array of lenses
• CPC Class Codes: H04N 2201/02493 Additional optical elements not otherwise provided for, e.g. filters, polarising plates, masks or apertures

Abstract

An optical device of the present invention includes an input aperture array formed with a plurality of input apertures at a preselected period of arrangement. An output aperture array is formed with a plurality of output apertures respectively facing the input apertures at a preselected period of arrangement. An aperture array intervenes between the input aperture array and the output aperture array and is formed with apertures respectively facing the input apertures and output apertures at a preselected period of arrangement. The aperture array satisfies the following two conditions:

t2>T·(r+R)/(P+r-ρ)

t1<t2·(P-ρ-r)/(P+ρ-r)

where T denotes a distance between the input aperture array and the output aperture array, r denotes the half-width of the input apertures, ρ denotes the half-width of the output apertures, R denotes the half-width of the apertures, t1 denotes a distance between the input aperture array and the input surface of the aperture array, and t2 denotes a distance between the input aperture array and the output surface of the aperture array.

Claims

1. An optical device comprising:

an input aperture array formed with a plurality of input apertures at a preselected period of arrangement;

an output aperture array formed with a plurality of output apertures respectively facing said plurality of input apertures at a preselected period of arrangement; and

an aperture array intervening between said input aperture array and said output aperture array and formed with apertures respectively facing said plurality of input apertures and said plurality of output apertures at a preselected period of arrangement;

said aperture array satisfying the following conditions;

space="preserve" listing-type="equation">t2>

T·

(r+R)/(P+r-ρ

)

space="preserve" listing-type="equation">t1<

t2·

(P-ρ

-r)/(P+ρ

-r)

where T denotes a distance between said input aperture array and said output aperture array, r denotes a half-width of said input apertures, ρ

denotes a half-width of said output apertures, R denotes a half-width of said apertures, t1 denotes a distance between said input aperture array and an input surface of said aperture array, and t2 denotes a distance between said input aperture array and an output surface of said aperture array.

2. An optical device comprising:

an input aperture array formed with a plurality of input apertures at a preselected period of arrangement;

an output aperture array formed with a plurality of output apertures respectively facing said plurality of input apertures at a preselected period of arrangement; and

a thin film aperture array layer intervening between said input aperture array and said output aperture array and formed with apertures respectively facing said plurality of input apertures and said plurality of output apertures at a preselected period of arrangement;

said thin film aperture array layer being located at at least one position spaced from said input aperture array by a distance which is an integral multiple of T/2^k where T denotes a distance between said input aperture array and said output aperture array, and k is a positive integer.

3. An optical device as claimed in claim 2, wherein said aperture array layer is positioned in a range of at least two positions spaced from said input aperture array by integral multiples of T/2^k.