JPH01134326A - optical scanning device - Google Patents

Abstract

PURPOSE:To simplify an optical system and to greatly shorten measurement time by providing an optical means which forms a light beam from a light source into thin-plate type luminous flux and a specific light receiving part in a rotary drum. CONSTITUTION:In the rotary drum 2 which is driven by a rotary driving means 10, 1st, 2nd, and 3rd reflecting mirrors 12, 14, and 15 where the light beam from the light source 6 such as a laser is projected, a cylindrical lens 16, and the light receiving part 18 are arranged and fixed. When the rotary drum 2 is rotated by a motor 10, the light beam from the light source 6 becomes the plate-shaped luminous flux which has a constant spread angle theta through an optical system in a plane crossing the center axis 10. This luminous flux is projected on a sample 4 and transmitted light is received by the light receiving part and recorded. Consequently, the optical system is simplified, data are gathered only through the rotation of the drum 2, and the measurement time is greatly shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION (-r) Industrial Application Field The present invention relates to an optical scanning device that non-destructively obtains tomographic information within a transparent object by scanning an original beam.

(Conventional technology and its problems) In order to efficiently obtain tomographic information inside the object using the source beam, it is necessary to uniformly and quickly collect as much data as possible over the entire circumference of the measurement area of the object. In the ninth step, as shown in Figure 5, while scanning the original beam in sectors at a constant swing angle θ to cover the measurement area of one object B, p along the circumferential direction with the radiation position of the original beam relative to B as the center of the object Bi
l.

One method is to sequentially change the pitch p2, p3, . . . at constant pitch intervals over the entire circumference.

A conventional optical scanning device for realizing this purpose is disclosed in Japanese Patent Application Laid-Open No. 61-265553.

In this optical scanning device, a rotating mirror is placed on the original axis of a light beam emitted from a light source to reflect the light in a direction perpendicular to the original axis of the original beam. A large number of first plane reflection mirrors are arranged along the circumference to reflect the original beam from the rotating mirror in the direction along the total rotation axis, and each first plane reflection mirror is placed at a position opposite to each first plane reflection mirror. A second plane reflection mirror is arranged to reflect the original beam from the plane reflection mirror in a direction perpendicular to the rotation axis, and further, a second plane reflection mirror is disposed at a position opposite to each second plane reflection mirror.
A configuration is adopted in which a light receiving section is arranged to receive and receive the reflected light Xk from the plane reflecting mirror.

Therefore, in this device, the beam emitted from the light source is sequentially reflected by the rotating mirror, the first plane reflection mirror, and the second plane reflection mirror, and is received by the light receiving section. that time,
When the rotating mirror is rotated, the first,
The reflection angle of the original beam reflected by the second reflecting mirror changes, and as a result, for each pair of 11th and 2nd reflecting mirrors, the original beam scans in sectors based on each position of the 8g2 reflecting mirror. Sanru. Moreover, as the reflecting mirror rotates, the radiation position of the six-element beam relative to the subject changes at constant pitch intervals over the entire circumference in the t-circumferential direction with the subject as the center.

By the way, in the above-mentioned conventional device, the first and second reflecting mirrors and the light receiving section remain fixed, and the original beam is scanned by rotating a rotating mirror arranged on the original axis. Although this method has the advantage of being able to scan the original beam at high speed and instantly sample the necessary data, it has the following problems. That is, 1, [E! It is necessary to align the optical axes of each of the first and second reflecting mirrors and the light receiving sections, which are arranged in large numbers along the circumference around the rotation axis of the J-turn mirror, and it takes time and effort to adjust the optical system. In particular, if the resolution of a tomographic image obtained based on original beam scanning is to be increased, the number of reflecting mirrors and light receiving sections will increase accordingly, making adjustment of the optical system that much more troublesome.

The swing angle θ (see Figure 5) of the n1-dimensional beam is determined by the positional relationship of the first and second reflecting mirrors with respect to the rotating mirror.
Therefore, it is difficult to enlarge or reduce the measurement area. That is, when the measurement area of the object B is large, the swing angle θ of the original beam needs to be increased accordingly.

This can be achieved by increasing the distance between the rotating mirror and the first reflecting mirror, but this increases the size of the entire device.

However, in order to increase the swing angle θ of the original beam without changing the distance between the rotating mirror and the first reflecting mirror, it is sufficient to increase the circumferential length of the first and second reflecting mirrors. Then, the number of first and second reflecting mirrors distributed on the circumference decreases, resulting in a decrease in resolution.

Furthermore, the present applicant has filed Japanese Patent Application No. 120931/1987 to solve the above-mentioned problems, but this device also requires a lot of time for measurement because it moves the light beam or the sample.

(c) Means for solving the problem: A rotating drum in which a hole for placing a subject is formed in the center, and a rotational drive means for rotationally driving this rotating drum, and a light source inside the rotating drum. Former beam from? It has an optical means that forms a thin plate-shaped light beam in a plane orthogonal to the central axis of the rotating drum, and a light receiving part that receives the transmitted light beam from the object to be irradiated with the plate-shaped light beam. It is characterized by

A cylindrical lens is an example of an optical means for converting the original beam into a thin plate-shaped light beam.

(2) Effect If the above configuration is used, when the rotary drum is rotated in one direction by the rotary drive means, the n1 original beam fixedly disposed inside the rotary drum is converted into a thin plate-shaped light beam. The optical means and the light receiving section are also rotated.

During this rotation, the optical means converts the original beam from the light source into a thin plate-shaped light beam in a plane perpendicular to the central axis of the rotating drum. Then, the original beam emitted from the optical means is received by the light receiving section.

FIGS. 4(a) and 4(b) show the emission state of the original beam according to the present invention.
).

In addition, FIG. 4(a) shows a case where a lamp is used as a light source, and FIG.

(E) Embodiment FIG. 1 is a perspective view showing the overall configuration of an optical scanning device of the present invention;
Figure 2 is a vertical cross-sectional view of the optical scanning device, and Figure 3 is the I-
FIG. In these figures, the sign +j
Reference numeral 1 indicates the entire optical scanning device, and reference numeral 2 indicates a rotating drum, which is rotatably supported by rollers 3.

A hole 2a for placing the subject 4 is formed in the center of m parts of the rotating drum 2, and an introduction hole 2b for the original beam from a light source 6 such as a laser is formed in the center of the other side. There are n. Furthermore, a gear 2C is formed at the end of the outer peripheral wall of the rotating drum 2 over the entire circumference.

A small gear 8 is engaged with the teeth 42c, and the small gear 8 is fixed to a drive shaft of a motor 10 serving as a rotational drive means for rotationally driving the rotating drum 2.

On the other hand, inside the rotating drum 2, first, second, and third reflecting mirrors 12, 14, 15, a cylindrical μ lens 16, and a light receiving section 18 are respectively fixedly arranged.

The first reflecting mirror 12 is arranged at an angle of 45° on the original path of the original beam emitted from the light source 6.
The original beam is reflected in a direction perpendicular to the central axis O of the rotating drum 2. The second reflecting mirror 14 is disposed parallel to and facing the first reflecting mirror 12 and reflects the original beam from the first reflecting mirror 12 in a direction parallel to the central axis 0. The third reflecting mirror 15 is arranged opposite to the second reflecting mirror 14, and this mirror 15 is connected to the original beam from the second reflecting mirror 14. The light is reflected in a direction perpendicular to the central axis O, and a cylindrical lens 16 is disposed on the reflection source axis. The cylindrical lens 16 emits a plate-shaped (fan-shaped) light beam to the light receiving section 18 .

Further, the light receiving section 18 is located at a position facing the cylindrical lens 160 and is arranged along the circumferential direction of the rotating drum 2.
It is composed of an L-ratio photodiode array, which receives the original beam emitted from the cylindrical lens 16 and outputs an electric signal corresponding to the intensity of the original beam. Note that 20 is a cover that covers the entire rotating drum 2.

In the above configuration, when the rotating drum 2 is rotated in one direction by the motor 10, the first, second, and third reflecting mirrors 1 fixedly arranged inside the rotating drum 2 are accordingly rotated.
2.14.15 The cylindrical lens 16 and the light receiving section 18 are also rotated together.

Therefore, the original beam from the light source 6 is sequentially reflected by the first, second, and third reflecting mirrors 12, 14, and 15, and
The cylindrical lens 16 has a constant spread angle U so as to cover the entire measurement area of the subject 4 in a plane orthogonal to the central axis O of the rotating drum 2.

Furthermore, as the rotating drum 2 rotates, the radiation position of the original beam relative to the subject 4 changes sequentially over the entire circumference at constant pitch intervals along the circumferential direction with the subject as the center.
'L, 6° Then, the original beam that is emitted from the cylindrical lens 16 and transmitted through the subject 4 is received by the light receiving section 18.

Accordingly, the reflected optical path is fixed relative to the rotating drum 2, but since the entire rotating drum 2 rotates, the original beam is scanned over the entire circumference of the measurement area of the subject 4. It turns out.

In this embodiment, the light source 6 is provided outside the rotary drum 2, but the light source 6 is not limited to this.
It is also possible to fix the lens to the cylindrical lens 16 inside the rotating drum 2 so as to face the cylindrical lens 16 to form a cage structure. In this case, the first, second and third reflecting mirrors 12.14.15 k
Can be omitted.

(f) Effects As described above, according to the present invention, the structure of the reflective optical system is simpler than the conventional one. Furthermore, since no light beam or sample drive is required, data can be collected only by rotating the rotating drum, and measurement time can be significantly shortened.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the entire optical scanning device of the present invention, and FIG.
The figure is a longitudinal cross-sectional view of the optical scanning device, Figure 3 is a cross-sectional view along the line ``T'' in Figure 2, and Figure 4 is the emission state of the original beam. FIG. 5 is an explanatory diagram showing the scanning state of the original beam with respect to the subject in the conventional apparatus. 1... Optical scanning device 2... Rotating drum 10... Rotating drive means (motor

Claims (1)

[Claims] (1) A rotating drum with a hole for placing a subject formed in the center and a rotational drive means for rotationally driving this rotating drum; Optical scanning characterized by having an optical means to form a thin plate-shaped light beam in a plane orthogonal to the central axis, and a light receiving section that receives a transmitted light beam from a subject irradiated with the plate-shaped light beam. Device.