Let the length of the measured object be l? ,? Zoom in with a biological microscope, and the middle image length is l? ,? Measure l with a micrometer eyepiece inserted into the lens barrel of a biological microscope? ,? Then l=l'/β0
Where is β0? Is the measured objective magnification. Because the front focus position of the micrometer eyepiece is much higher than the original current focus position of the biological microscope, the optical separation becomes larger. From nearby
Such as the formula β0? =Δ/? f0？ (? f？ 0? Is the focal length of the objective lens? Do you see it? Measured? 0? Is greater than the nominal value displayed on the selected objective. . So we should find out in the experiment? 0,? That is, the calibration of the microscope eyepiece is calibrated.
For standard stone foot crops, then the length l is known? 0? (? Can be the distance between two dashes)? ,? Enlarged to become the intermediate image length l'0,? Find β0=l'0/l0.
2 measurement methods and experimental results
2.？ 1? Experimental instruments and equipment
XSP-？ 16A？ Type b biomicroscope, QCJ2? A micrometer eyepiece, standard stone ruler (? The total length is1mm. * * * 100? Grid, each grid is 0. ? 0 1mm)？ ,? Transmission grating (? 300? Articles/? mm)
2.？ 2? Find β0
Insert the micrometer eyepiece into the lens barrel of the biological microscope. Objective lens 40×? ,? Clamp the standard stone foot on the stage. According to the operating rules of the biological microscope, we can see the clear stone foot scale in the field of view of the micrometer eyepiece. Data obtained by micrometer eyepiece reading method, such as table 1? As shown in the figure.
Get an l? 0=? 0.？ 0 1mm，？ Then |? m2？ -? m 1|？ Is the distance between two adjacent scribed lines of a standard stone ruler L? 0? What is the intermediate image length magnified by the objective lens? β0=l'0/l0=？ 0.449/0.0 1=? 44.9
Especially? In the process of adjusting the biological microscope, we should pay attention to the effective working distance of the objective lens (? When the objective lens indicates 40 times, the effective working distance is 0. 53mm)？ . The glass thickness of the standard stone foot used in this experiment is 1. 52mm，？ If the scale line is engraved on the front of the glass placed upward, it can be observed. If the other side is placed upward, even if the objective lens is close to the stone foot, there is still 1. 52mm？ Distance? Then you can't observe it. The same,? Observe the transmission grating used in this experiment. The thickness is 1. 98mm)？ We should also pay attention to this.
2.？ 3? Measuring grating constant d
The measured transmission grating is used to replace the standard stone foot. Focusing, a large number of parallel gaps with equal width and equal spacing were observed. Where the score is considered as an opaque part. Read the value as shown in figure 1? As shown in the figure, Measure 20? Slot spacing? Pay attention to your position when reading. n 1？ Is the first gap (? Vertical rectangle) Left reading, n2? Is it the 20th? A gap (? Vertical rectangle) read on the left. So? By d=? a+？ b，？ n 1？ And n2? Yes 19? A grating constant value,? L=？ 19d=？ 19(? a+？ b)？ . See Table 2 for the measured data? show
l=l'/β0=2。 ? 927/44.？ 9=? 0.？ 062(? mm)
d=l/ 19=0。 ? 062/ 19? =? 3.？ 263* 10^-6(? m)