JPS58105521U - Optical low-pass filter for color signals - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Brief explanation of the drawing]

Figure 1 shows how false signals are generated, Figure 2 shows the response characteristics of the optical low-pass filter and the photoelectric conversion section of the image sensor to spatial frequencies, and Figure 3 shows the response characteristics of the optical comb filter element. This is a diagram showing the appearance of false signals when the attenuation pole frequency and the number of elements are changed. Figure 4 is a diagram showing the structure of an optical low-pass filter according to an embodiment of the present invention, and Figure 5 is a diagram showing the structure of an optical low-pass filter according to an embodiment of the present invention. FIG. 3 is a diagram showing color signal frequency characteristics when using an optical low-pass filter. In the drawing, reference numeral 11 indicates the response characteristic to the spatial frequency in the photoelectric conversion section of the image sensor, reference numerals 12 and 13 indicate the false signal characteristic caused by folding, and reference numeral 21 indicates the response characteristic of a single optical (rectangular filter element) with an attenuation pole frequency of 3.56 MHz. Characteristics, 22 Characteristics in the photoelectric conversion section of the image sensor, 23
is the characteristic of an optical low-pass filter using two optical comb filter elements with an attenuation pole frequency of 3°58 MHz.
1 is the characteristic when a single optical comb-shaped Lylter element with an attenuation pole of 3.58 MHz is used, 32 is the characteristic when two optical comb-shaped filter elements are used with an attenuation pole of 3.58 MHz, and 33 is the attenuation pole. 3.58 MHZ 10. Characteristics when set to 25 MHZ, 34 is attenuation pole 3,5S MHZ 10. 5MHz
Characteristics when using two elements, 35 is attenuation pole 3° 58MH
Characteristics when using three elements of z±0.5MHz and 3.58MH2, 41.43 is a λ14 phase plate, 42.44 is an optical (diamond-shaped filter element) with attenuation pole of 3.58 MHz. 25 - 0.5 1 exposure LI-Zumai ゛transition V - -2) -1-kL 1,3

Claims (1)

[Scope of utility model registration request] Using a stripe-like or dot-like color separation filter, at least two color signals, blue and red, are extracted from one color signal image sensor, and a broadband green signal or luminance signal is extracted from one or more other image sensors. In a color signal optical low-pass filter inserted into the incident optical path of the color signal image sensor in a color camera that is adapted to be taken out,
It is composed of a transparent material with optical-axial birefringence characteristics, and the separation direction of the ordinary and extraordinary light due to the birefringence is the horizontal scanning direction, and the basic spatial frequency caused by the separation interference of the ordinary and extraordinary light. The attenuation pole is ±500KH of the color signal spatial sampling frequency of the color signal image sensor.
1. An optical low-pass filter for color signals, characterized in that a plurality of optical comb-shaped filter elements having a wavelength of z or less are provided to a wavelength of λ made of a transparent material having optical-axial birefringence characteristics via a phase plate.