JPS6153526A - Microspectrophotometry - Google Patents

Abstract

PURPOSE:To enable microspectrophotometry with high accuracy, by reflecting incident light to the direction separating from an optical axis from a first reflective surface by an objective lens and subsequently reflecting the same to a condensing direction from a second reflective surface. CONSTITUTION:A specimen 7 being an object to be measured is arranged to a position 17 and only light in the vicinity of an optical axis among the light from the specimen 7 is reflected to the diection separating from the optical axis by a second reflective mirror 15 and subsequently reflected to a consensing direction from a first reflective mirror 14 to form an image at an image forming point 18. By this mechanism, only light, of which the incident angle to the specimen 7 is larger than an angle theta1 and smaller than the angle theta2, contributes to measurement. That is, because angles theta1, theta2 are clearly smller than respective angles theta3, theta4, when the specimen 7 is viewed from this point, light in the vicinity of the optical axis in a TV camera can take a value more approximate to an objective practical system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a microspectrophotometry method suitable for measuring the spectral transmission characteristics of a minute portion of an object to be measured.

[Background of the invention]

BACKGROUND ART Microspectrophotometry, which measures the spectral transmission characteristics of a minute portion of an object to be measured, is widely known, with no need to cite any known examples, and the measuring devices are sold out.

FIG. 1 is a conceptual diagram showing one optical system of a microspectrophotometry system applied to this microspectrophotometry method. In the figure, light emitted from a light source 1 is separated by a collimator mirror 2 and a spectroscopic prism 3, becomes monochromatic light, and illuminates a pinhole 5 by a collimator mirror 4. The image is formed on the sample 7. Here, when passing through the sample 7, after being modulated by the spectral transmittance of the sample 7, the shutter 9. Images of the sample 7 and the pinhole 5 are formed on the photoelectric device 11 via the optical system 10 .

In this case, the output of the photoelectric device 11 is given by the light wavelength Jl determined by the prism 3, the spectral transmittance of the sample 7, and K. In this way, the spectral transmittance characteristics of the sample 7 can be known, but the projection lens 6 and the objective lens 8 are required to have no chromatic aberration due to the nature of spectrophotometry, and from this point of view, they are shown in Fig. 2. Reflective lenses such as these are widely used. That is, in the figure, the light from the measurement point 12 on the sample 7 is not refracted by the glass body 13, and therefore the optical path does not change depending on the wavelength of the light. It is reflected by the reflecting mirror 15 of i2 and is imaged at point 1B.

However, according to microspectrophotometry using a reflective lens configured in this way, the angle near the optical axis with the optical axis is close to 0 degrees, that is, the angle of incidence of light to the sample 7 is around 90 degrees. There was an inconvenient problem in that the light did not contribute to the measurement.

In other words, when evaluating the transmittance of a light transmitting material with a finite thickness, when the angle of incidence of light on the sample is 90 degrees, it shows the minimum thickness, and as the angle of incidence increases, the thickness of the sample increases. However, the transmittance becomes small. In addition, when measuring colored objects, dichroic filters, etc. by optical interference, changing the incident angle of light will substantially change the thickness of the optical thin film that determines the optical interference characteristics, and the spectral transmission curve This means that it moves in the wavelength direction. Because of this phenomenon, the characteristics of dichroic filters are always defined by specifying the angle of light incidence.

Therefore, when using a dichroic filter, it is overwhelmingly assumed that the light incidence angle is 90 degrees, and the measurement suitable for this case is that with conventional reflective lens systems, the part around the light incidence angle of 90 degrees is excluded. Because of this, the error becomes extremely large, which is not desirable.

An example of an object that has to be measured by microspectrophotometry is a color separation filter in the form of a mosaic assembly, for example for a single tube color television imaging system. This color separation filter has a group of red light-reflecting dichroic filters with a width of about 15 μm and an arrangement pitch of about 30 μm formed on a transparent glass substrate, and a blue light-reflecting dichroic filter of the same shape with an intersection angle of about 20 degree of variation on this filter group. A filter group is formed. In this case, the size of the part to be spectroscopically measured is about 15 μm across opposite sides, and cyan, yellow, green, and yellow with one apex angle of about 20 degrees of variation.
The transparent part of the glass substrate is diamond-shaped. When the dichroic filter section configured in this manner is measured using a conventional microspectrophotometry system having a reflective lens, the half-value wavelength at which the spectral transmittance is 50% is approximately 565 nm.
When this large-area dichroic filter is measured using a spectrophotometer with a normal light incident angle of about 90 degrees, it is 56.
It shows about 8 to 580 nm. Normally, when designing the color separation characteristics of a color television imaging system and performing manufacturing control, this degree of uncertainty in measurement data is extremely inconvenient in order to maintain product quality. It is desirable to perform measurement and evaluation using a light beam whose angle is close to approximately 90 f.

[Purpose of the invention]

Therefore, the present invention has been made in view of the above-mentioned problems, and its purpose is to perform highly accurate spectroscopy without error by using light whose incidence angle is around 90 degrees with respect to the object to be measured. It is an object of the present invention to provide a microspectrophotometry method in which photometry has gT capability.

[Summary of the invention]

In order to achieve such an object, the microspectrophotometry method according to the present invention uses a reflective objective lens that reflects and condenses the light transmitted or reflected from the object to be measured, and the light incident on this lens is Microspectrophotometry is performed by forming an optical system in which light is reflected in a direction that is discrete from the optical axis by a reflective surface, and then reflected in a convergent direction by a second reflective surface.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 3 is an enlarged view of a main part of an objective lens for explaining an example of the microspectrophotometry method according to the present invention), and the same parts as in the previous figures are given the same reference numerals. In the figure, a sample 7 to be measured is placed at a point 17 corresponding to the imaging point 16 in FIG. At this time, of the light from the sample 7, only the light near the optical axis is reflected by the second reflecting mirror 15 in a direction that diverges from the optical axis, and then reflected by the first reflecting mirror 14 in a converging direction to form an image point. 181C image is formed. In this case, the imaging point 18 will be located at a position corresponding to the measured point 12 in FIG.

According to the 6111 optical method, the angle of incidence of light on the sample 7 is the angle θ8 with respect to the optical axis in the case of a conventionally arranged reflective objective lens.
Light rays with a large diameter and a small angle θ4 contributed to the measurement, but in the present invention, the angle θl is also large and a light ray having an incident angle more formal than the angle θS contributes to the measurement. In other words, the angle θl is clearly smaller than the angle θ8, and the angle θ2 is clearly smaller than the angle θ4, so from this point of view, it is better to use a value that is closer to that of a practical system where light near the optical axis of a television camera is targeted. You can take it. In this case, of course, there is a disadvantage that the amount of measurement light decreases, but this is within a range that can be sufficiently compensated for by increasing the amount of light from the light source, increasing the gain of the measurement system, etc., and is extremely effective. Furthermore, in a system in which the surface of the sample 7 is irradiated spectrally with the image of the pinhole 5 as shown in FIG. 1, it is desirable to use a reflective lens for the projection lens 8. It is desirable to adopt an arrangement similar to that of the invention. It is also possible to use other microscopic spectroscopy systems, such as a system in which the sample 7 is irradiated with monochromatic diffused light instead of the projection lens 6 shown in FIG. At least, it is effective to use an inverted reflective lens as in the present invention for the objective lens.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to effectively utilize light having an angle of incidence of about 90 degrees to the object to be measured, making it possible to perform spectrophotometry at high h7 degrees without error. Effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a microspectrophotometric optical path using a conventional reflective lens system, Fig. 2 is an enlarged view of the reflective objective lens section of Fig. 1, and Fig. 3 is an example of the microspectrophotometric method according to the present invention. FIG. 3 is a diagram showing the relationship between the object to be measured and the gap position of the reflective objective lens for explanation. 1 - Light source, 2 fists... Collimator mirror, 361
111@spectral prism, 46ass collimator mirror,
5II...pinhole, 6...projection lens, 7.
・ψ・Sample, 8...Objective lens, 8.Fist-shutter, 10...Fist optical system, 11j...Photoelectric device, 12...Point to be measured, 13...
・Glass body, 14 fists ・@1 First reflector, 15-...
Second reflecting mirror, 16...imaging point, 1ryō, fist...point,
18...11@imaging point. Figure 1 VAZ map 3

Claims (1)

[Claims] A microspectrophotometry method in which the spectral transmittance of the object is measured by irradiating the object with light projected from a projection lens and making the light transmitted or reflected by the object enter an objective lens. A microscope characterized in that at least the objective lens forms an optical system that reflects the incident light in discrete directions from the optical axis on a first reflective surface, and then reflects it in a converging direction on a second reflective surface. Spectrophotometry.