Optical system comprising a diffractive optical element, and method of designing the same

• US 6,330,109 B1
• Filed: 04/25/2001
• Issued: 12/11/2001
• Est. Priority Date: 05/13/1998
• Status: Active Grant

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Ishii, Tetsuya
• Primary Examiner(s): Chang, Audrey
• Assistant Examiner(s): WINSTEDT, JENNIFER E
• Application Number:
  US09/840,867
• Publication Number:
  US 20010043397A1
• Time in Patent Office: 230 Days
• Field of Search: 359/566, 359/569, 359/571, 359/576
• US Class Current: 359/571
• CPC Class Codes: G02B 5/1866 Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence

Abstract

The invention relates to a method of easily and quantitatively determining the diffraction efficiency of a relief type diffraction optical element, and provides a method of designing an optical system comprising a diffractive optical element using diffraction efficiency as at least one estimation index. The diffractive optical element is a transmission blaze grating constructed of a relief having a sawtooth shape in section. The transmission blaze grating having a side wall substantially vertical to a grating surface. The estimation index is given by a predetermined mathematical expression including at least a phase difference due to a relief discontinuity and shadow effects thereof. The mathematical expression includes as the shadow effects of said discontinuity at least a light attenuation effect dependent on an angle-of-incidence and a light attenuation effect independent on the angle-of incidence in a separate manner.

Claims

1. An optical system, characterized by comprising a transmission blaze grating constructed of a relief having a sawtooth shape in section and satisfying the following relationships:

2. The optical system according to claim 1, wherein a sign of an angle θ

_en of incidence of all chief rays on an entrance surface upon incidence on said transmission blaze grating with respect to a normal to a grating surface coincides with a sign of an order of diffraction m at which diffraction efficiency is maximized.