Spot diameters of just a few thousands of an inch can readily be attained with convenient short focal length lenses.
用普通的短焦距透镜不难得到直径只有几十微米的光点。
short focal length (high aperture) lens
短焦距(大孔径)透镜
variable focal length (cylindrical) lens
变焦(距)(圆柱)透镜
manual zoom lens
(镜头)手控可变焦距透镜
rear-controlled zoom lens
背面调整变焦距透镜
Measurement of optical surface and foci of long focal length lens by CGH
计算全息法测量长焦透镜面形和焦距
The focal length differs with the thickness of the lens
焦距长底随透镜的厚度而变化。
(physiology) the automatic adjustment in focal length of the lens of the eye.
（生理学）用眼的透镜来自动调节焦距。
Measurement of Long Focal Length of Lens Utilizing Talbot Effect and Morie Technique;
利用泰伯—莫尔法的透镜长焦距测量
The Study of Measuring Convex lens Focal Distance with CCD;
用CCD测量凸透镜焦距实验的研究
Further study on thin-lens focal length measurement experiment;
再议对薄透镜焦距测定的进一步研究
Improvement on a Device in the Experiment of the Measurement of the Thin Lens Focallength;
“薄透镜焦距的测定”实验装置的改进
Research on Focal Depth in the Experiment of Thin Lens' Focal Length Measurement
薄透镜焦距测量实验中焦深问题的研究
They have a focal length, and where an image is formed depends on a combination of the focal length and the distance between the object and the lens.
透镜有焦距，而影像形成的位置，取决于焦距及物体与透镜距离的组合。
Measurement for the Long Focus Length of Lens by Images of Moire Fringes
利用莫尔条纹的计算机图象测量长焦距透镜焦距
The focal length of the conelensing lens should be such that the image of the source just fills the projecting lens.
聚光透镜的焦距应使光源的像正好照满放映透镜。
a photographic lens with a short focal length used to take pictures at short ranges.
带有短焦距在小范围内照相的照相机镜头。
The focal length of a given lens is different for different colors.
一个特定的透镜的焦距因颜色的不同而不同。