Lens Device Ghost Suppression via Dual Optical Filter

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Solution Overview

Problem

Existing lens devices struggle to effectively suppress ghosts and flares, particularly in imaging systems where band-pass filters are used, as they often result in strong reflections due to the combination of light paths through different wavelength regions.

Innovation Solution

A lens device configuration featuring a filter unit with band-pass and band-stop filters arranged in specific optical paths, where band-stop filters absorb light outside their transmission bands, reducing reflections and ghosts by ensuring light is either transmitted or absorbed within the intended wavelength regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If band-pass filters are used in the optical path, then light transmission in specific wavelength regions is improved, but strong reflections occur causing ghosts and flares

Engineering Contradiction:

Improvelight transmissionVSAvoidreflections causing ghosts and flares

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

A second optical filter (band-stop filter) is introduced as an intermediary element between the first optical filter (band-pass filter) and the imaging sensor. This intermediate filter absorbs the reflected light in the passband region, preventing it from reaching the sensor and causing ghosts and flares, while maintaining the wavelength-selective transmission function of the first filter.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful reflected light from the band-pass filter into a beneficial effect by using the second optical filter to selectively absorb these reflections. The reflected light that would normally cause ghosts and flares is now absorbed in a controlled manner, transforming a harmful phenomenon into an opportunity for improved image quality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Measurement precision

If multiple optical filters with different wavelength regions are combined, then spectral selectivity is improved, but the complexity of the optical system increases

Engineering Contradiction:

Improvespectral selectivityVSAvoidoptical system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention merges the functions of wavelength selection and reflection suppression into a single optical path by combining a band-pass filter and a band-stop filter. The first filter selects specific wavelength regions for transmission, while the second filter suppresses reflections in those same regions, achieving both spectral selectivity and ghost reduction without requiring separate optical paths or complex additional components.

Inventive Principle:

Principle #5Merging (Combining)

3Object-generated harmful factors

If second optical filters are added to suppress reflections, then ghosts and flares are reduced, but the device complexity increases

Engineering Contradiction:

Improveghosts and flaresVSAvoidfilter configuration complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The second optical filter is designed with local quality characteristics, having high absorption only in the specific passband wavelengths of the first filter while maintaining high transmission in other wavelength regions. This localized absorption property allows the filter to suppress ghosts and flares only where needed (in the passband regions) without affecting the overall spectral transmission characteristics of the optical system.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration significantly reduces ghosts and flares by ensuring that light is either transmitted or absorbed within the intended wavelength regions, improving image quality by minimizing unwanted reflections.

Implementation Method 1

a first optical filter that has a light transmission band in a specific wavelength region

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

a second optical filter that has a light absorption band in a wavelength region which is different from the light transmission band of the first optical filter

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS20240230971A9Lens device, imaging apparatus, and filter unit

Publication Date: 2024.07.11 FUJIFILM CORP

AI summary

Provided are a lens device, an imaging apparatus, and a filter unit capable of suppressing occurrence of ghosts and flares. The lens device includes a first optical filter and a second optical filter in order from an object side in an optical path. The first optical filter is composed of an optical filter (for example, a band-pass filter) that has a light transmission band in a specific wavelength region. The second optical filter is composed of an optical filter (band-stop filter) that has a light absorption band in a wavelength region which is different from the light transmission band of the first optical filter.