Atchison D A, Bradley A, Thibos L N, Smith G
Centre for Eye Research, School of Optometry, Queensland University of Technology, Brisbane, Australia.
Optom Vis Sci. 1995 Apr;72(4):279-84. doi: 10.1097/00006324-199504000-00010.
The simple Badal Optometer consists of a movable target and a fixed positive power lens placed at its focal distance away from the eye. The perceived angular size of the target is independent of target position and the power scale is linear. Limitations of the simple Badal Optometer include restriction of negative (myopic) ocular vergence range, the need for targets to be small, and the problem of "proximal" accommodation. We describe two modifications to the Badal system in which these limitations may be overcome by the use of a movable auxiliary optical system. In one modification, the movable auxiliary system consists of a target and positive lens which together may provide a virtual "target" for the Badal lens and thus increase the negative range. In the second modification, the Badal lens is positioned as it would normally be, but the target is an image of a distant stimulus created by the auxiliary lens. The target position (and hence the ocular vergence) is changed by moving the auxiliary lens. The distant target eliminates the proximal accommodative stimulus and allows spatial detail near the resolution limit to be displayed.
简单的巴达尔验光仪由一个可移动的目标和一个固定的正透镜组成，该正透镜放置在距眼睛其焦距的位置。目标的感知角大小与目标位置无关，且屈光度刻度是线性的。简单巴达尔验光仪的局限性包括对负（近视）眼聚散范围的限制、对小目标的需求以及“近点”调节问题。我们描述了对巴达尔系统的两种改进方法，通过使用可移动的辅助光学系统可以克服这些局限性。在一种改进方法中，可移动的辅助系统由一个目标和一个正透镜组成，它们共同可为巴达尔透镜提供一个虚拟“目标”，从而增加负屈光度范围。在第二种改进方法中，巴达尔透镜按正常位置放置，但目标是由辅助透镜产生的远处刺激的图像。通过移动辅助透镜来改变目标位置（从而改变眼聚散度）。远处目标消除了近点调节刺激，并允许显示接近分辨率极限的空间细节。
