Design Principles of the LVT-2 Model Laser Instrument for the Measurement of Visual Characteristics.

摘要

The LVT-2 model laser visual acuity measuring instrument, after its model improvement, it not only is capable of measuring the visual acuity of retina (LVA), but also capable of measuring the MTF of retina. The light path system of the instrument has three sections. One is a double light bundle common path interference system making use of double Dufu prisms to divide bundles. It uses the movement of a reflection lends M2 in order to change the interval distance of the two mutually interfering bundles. As a result of this, it changes the spacial frequency of the interference bands. This acts as the light path to measure LVA. The second is the background light set composed of such components as the tungsten filament lamp T sub L, the interference filter optical plate OF, and the polarization lens P2. It is used in order to form, on the retina, a uniform background base light. Through adjustments of the dispersion prism B in the light path, adjustments are made in the degree of contrast change I sub O/I sub u measuring the MTF of the retina. Chinese translations. (JHD)