JPS60231123A - Spectrophotometer - Google Patents

Abstract

PURPOSE:To enable high speed scanning, by reflecting the reflected light of a spectroscopic optical system forming a spectrum image curved in a circular arc shape by a reflective mirror and rotating a cylinder having a plurality of slits to perform scanning. CONSTITUTION:The luminous flux of a light source 1 passes through a specimen measuring part 2 and the inlet slit 3 of a spectrometer and the light reflected by a concave diffraction grating 4 is formed into a spectrum image (i) along a Rowland circle R. A flat mirror 12 is provided between the diffraction grating 4 and the spectrum image (i) on the Rowland circle to be originally formed and reflects the reflected light from the concave diffraction grating 4 to form a spectrum image I along a circular arc (r). This circular arc (r) is formed by folding back a part of the Rowland circle R along the straight line passing the surface of the mirror 12. A cylinder 5 has a plurality of slit grooves S and the light from the slit S of the slit cylinder 5 rotating to the direction shown by the arrow is scanned in the arrangement direction of a wavelength by the detector 6 outside the cylinder 5. By this method, the spectroscopic optical system enables high speed scanning in a stationary state.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a spectrophotometer suitable for performing spectroscopic analysis such as emission analysis or absorption analysis.

2. Prior Art In order to perform wavelength scanning with a conventional spectrophotometer, a spectroscopic element such as a diffraction grating or a prism is moved. That is, the entrance slit and the exit slit of the spectrometer are fixed, and the spectroscopic element is moved so that a specific wavelength portion on the spectrum formed by the spectroscopic element is located on the exit slit.

In this case, the wavelength of the spectral light located on the output slit is determined by the position of the appropriate part of the mechanism that drives the spectroscopic element, so the driving mechanism of the spectroscopic element is required to be highly accurate, and it must be able to move at high speed. In addition, high-speed wavelength scanning is difficult because it is necessary to drive the spectroscopic element carefully in order to obtain reproducibility of the wavelength of the emitted light. For this reason, spectroscopic tracking of time-varying phenomena is often difficult or practically impossible.

C. Purpose The present invention aims to enable high-speed wavelength scanning with a spectrophotometer.

2. Configuration A spectroscopic optical system that forms a spectral image curved in an arc shape, and a rotating slit in which one or more slits extending in the generatrix direction are provided in a cylindrical surface with a circumference that follows the spectral image. This is a spectroscopy/diameter which consists of a tube and is characterized in that by rotating this slit tube in one direction, the svector image plane is scanned by the slit.

E. Example diagrams show examples of the present invention. In FIG. 1, 1 is a light source, 2 is a sample measuring section =l, 3 is an entrance slit of a spectroscopic optical system, and 4 is a concave diffraction grating, both of which are arranged on one Rowland circle R. The concave diffraction grating is curved into an arc whose radius of curvature is the diameter of the Rowland circle, and the center of curvature is at the R10 point of the Rowland circle. Therefore, it enters from the entrance slit 3,
The light reflected and diffracted by the diffraction grating 4 forms a spectral image along the Rowland circle R. Reference numeral 12 denotes a plane mirror disposed between the diffraction grating 4 and the spectral image 1 to be originally formed, and is oriented slightly downward with its reflective surface facing away from the plane of the paper in the figure. The diffracted light is reflected by this mirror to form a spectral image (2) along the arc r. This arc is a straight line that passes through a part of the Roland circle R through the surface of the mirror 12! It was folded back. 5 is a slit cylinder having a circumference along the above-mentioned arc r, and a slit groove S is transparently provided along the generatrix thereof. Reference numeral 6 denotes a photodetector placed outside the slit tube with its spectrum detector and light-receiving surface facing each other.

When the slit tube 5 is rotated in the direction of the arrow in the figure (or in the opposite direction), the slit groove S scans the spectrum in the direction of the wavelength arrangement, and as the slit S moves, light of different wavelengths is transmitted to the photodetector 6. incident on .

FIG. 2 is a side view of the above embodiment. 7 is slit tube 5
A pulse motor rotates the motor 7, and 8 is a rotation control circuit for the motor 7. Reference numeral 11 denotes a photocoupler for detecting the slit position, which detects a protrusion P protruding from the edge of the slit cylinder 5 in correspondence with the slit groove S, and upon receiving the detection signal, the data processing circuit 9 generates a drive pulse for the pulse motor 7. This counting data is used as wavelength information. The data processing circuit also samples the output of the photodetector 6 using the drive pulse of the motor 7 as a sampling signal, and stores it in the memory together with the wavelength information.
Display the spectral image profile.

FIG. 3 shows another embodiment of the present invention, in which the entrance slit J-3 and the exit slit S are arranged off-plane with respect to the diffraction grating 4 (a Rowland circle including the normal to the center of the diffraction grating 4). The entrance and exit slits are arranged at different positions above and below the surface), and the center of the slit tube 5 is coaxial with the Rowland circle.

Although the above embodiment is a single-beam type device, if the sample measuring section is configured as a double-beam type and the switching period of the three beams is made sufficiently short compared to the wavelength scanning time by the slit tube, the double-beam type can also be used. It goes without saying that the present invention can be practiced.

Effects The spectrophotometer of the present invention has the above-described configuration, and performs wavelength scanning by rotating a cylinder provided with a slit along the slit image plane, and the spectroscopic optical system remains stationary. Since high-speed scanning is possible and the wavelength reproducibility remains the same as before, it becomes easy to spectroscopically track rapidly changing phenomena.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view of an apparatus according to an embodiment of the invention, FIG. 2 is a side view of the same embodiment, and FIG. 3 is a perspective view of another embodiment of the invention. DESCRIPTION OF SYMBOLS 1...Light source, 2...Sample measurement part, 3...Incidence slit, 4...Concave diffraction grating, 5...Slit cylinder, 6
... Photodetector, 7... Motor for rotating the slit tube, 8... Motor drive control circuit, 9... Data processing circuit, 1o... CRT display device, 11... Photocoupler, 12 ...Surface mirror, S...Slit groove, R...
Roland circle, P...Protrusion for position detection provided on the slit tube 5. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] A spectrophotometer characterized by having a slit tube for spectroscopy that forms a spectral image curved in an arc, and by rotating the slit tube, the cis vector image surface is scanned by the slit. Total.