JPS6041538Y2 - Schlieren projection device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a Schlieren optical system that performs high-intensity projection.

With the development of the information industry, large-screen, high-brightness projection displays are becoming important in fields such as education, industry, and the military.

The projection display is CRT (Cathode Ra).
y Tube) and methods that use light valves.

In particular, the latter is capable of high-resolution, high-brightness displays;
There are research methods such as oil film method, photochromic method, method using ferroelectric material such as PLZT, and method using light valve using photoconductor and elastomer or liquid crystal.
Development is underway.

A schlieren optical system is usually used for projection of the light valve, and a xenon lamp is used as the light source.

However, the light source of the Schlieren optical system usually needs to be a point light source with good coherence, and spatial uniformity of the light amount distribution is also required, and the xenon lamp is insufficient in this respect.

In particular, horizontal xenon lamps that project a large amount of light use a perforated mirror, so they have an annular light amount distribution at the output end and do not become a point light source.

FIG. 1 shows an example of a conventional schlieren projection device using a horizontal xenon lamp and a reflection type light valve.

FIG. 2 is a partially enlarged view of FIG. 1, showing the optical system near the schlieren stop.

Light from a xenon lamp 1 is focused by an ellipsoidal mirror 2, converted into a parallel beam by a lens 3, and then focused by a lens 4.

The condensed light beam is reflected by the Schlieren stop 5 which has a portion of the mirror, passes through the lens 6, and becomes a parallel light beam, which becomes the input image 11.
incident on .

The reflected light from the input image passes through the lens 5 again, and then passes through the opening of the Schlieren stop 5 to form a projected image 12.

At this time, in order to separate the light flux incident on the lens 6 and the reflected light flux from the input image 11 at the Schlieren stop 5 as shown in FIG. 2, it is necessary to make these light fluxes enter the lens obliquely. .

In an optical system using a horizontal xenon lamp as shown in FIG. 1, the light intensity distribution of the condensed light beam has a donut-shaped distribution as shown in FIG. 3, which is far from a point light source.

For this reason, a bright lens with a large aperture is required to separate both beams on the Schlieren stop 5, and since the oblique incidence angle becomes large, the influence of lens aberrations cannot be ignored.

In actual projection, it becomes difficult to simultaneously focus on both the left and right end portions of the projected image, which significantly reduces the features of a projection device aimed at high-resolution projection.

An object of the present invention is to eliminate the above-mentioned drawbacks and realize a high-brightness, high-resolution Schlieren projection device using a horizontal xenon lamp.

According to the present invention, the apparatus is composed of a horizontal xenon lamp, an ellipsoidal mirror, a lens, and a Schlieren stop. and a condenser lens so that their optical axes intersect with each other at an arbitrary angle, and furthermore, the Schlieren stop is located on the optical axis at a position farther from the rear focal point of the first condenser lens, and the second condenser A Schlieren projection device is obtained which is characterized in that it has an optical system disposed within the front focal position of the lens.

FIG. 4 is a diagram showing the Schlieren stop 10 used in the present invention, showing a plan view a1 and a front view b.

The Schlieren stop 10 is a reflecting mirror in which a metal film 8 is deposited on a support 7, and a circular opening 9 is formed in the center when viewed from a 45° direction.

Such a perforated reflector can be easily manufactured using an aluminum reflector on a glass substrate.

FIG. 5 is a diagram for explaining the Schlieren projection device according to the present invention.

The configuration of the schlieren projection device according to the present invention is the same as that shown in FIG. 1 except for the schlieren stop, so the optical system around the schlieren stop will be described below.

The parallel light incident on the lens 4 is condensed, reflected by the Schlieren stop 10, and converted into parallel light by the lens 6.

The reflected light from the incident image 11 is Schlieren stop 10
A projected image 12 is formed by passing through the opening.

At this time, the distance d0 between the lens 4 and the Schlieren stop 10 is set to be larger than the focal length of the lens 4, and the parallel light beam is focused in front of the Schlieren stop 10.

The lens 6 is placed at a distance shorter than the focal length of the lens from the schlieren stop 10, and the reflected light from the input image 11 is focused and imaged on the schlieren stop 10.

By arranging it in this way, the image of the light source can be aligned with the lens 4.
and the inner diameter a1 of the annular zone of the light source image formed by the lens 6 is larger than the outer diameter a2 of the annular zone of the light source image formed by the lens 6, and The diameter can be made equal to the opening diameter D of the Schlieren stop.

Therefore, the Schlieren stop 10 from lens 4
The incident light is reflected without being vignetted and becomes the input image 11.
The reflected light is focused by the lens 6 and passes through the opening 9 of the Schlieren stop 10, and at this time, the mirror portion 8 cuts off the scattered light.

This optical system does not require a bright lens as the lens 6, since the incident light and the reflected light on the input image can be obtained symmetrically with respect to the lens optical axis.

Furthermore, the effect of lens aberration due to the oblique incidence angle is small, making it possible to project a large screen with high resolution.

As described above in detail, according to the present invention, a Schlieren projection device capable of high-intensity, high-resolution projection can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional schlieren projection device using a horizontal xenon lamp, Fig. 2 is a diagram for explaining a conventional schlieren stop, Fig. 3 is a diagram showing the light intensity distribution of a light source image, and Fig. 4 is a diagram showing a conventional schlieren projection device using a horizontal xenon lamp. The figure shows a schlieren stop according to the present invention, and FIG. 5 is a diagram for explaining the schlieren projection device according to the present invention. In the figure, 1 is a horizontal xenon lamp, 2 is an ellipsoidal mirror, 3, 4. 6 is a lens, and 5 and 10 are Schlieren stops.

Claims (1)

[Scope of utility model registration request] In a schlieren projection device composed of a horizontal xenon lamp, an ellipsoidal mirror, a lens, and a schlieren stop, the schlieren stop uses a plane reflecting mirror with a circular opening, and a first condenser lens and a first condenser facing the input image are used. 2 condenser lenses are arranged so that their optical axes intersect with each other at an arbitrary angle, and the Schlieren stop is placed on the optical axis at a position farther from the rear focal point of the first condenser lens and at the second condenser lens. 1. A Schlieren projection device comprising an optical system disposed within the front focal position of a second condenser lens.