Telescope Making
One-power Aiming Device
Written by Toshimi Taki
November 15, 2003
Revised August 28, 2004
Introduction
One-power aiming device consists of a convex lens, an acrylic plate, and a red light emitting diode (LED) covered with pinhole. The red LED is placed at the focal point of the lens and the lens projects the light from the LED on the acrylic plate. You can see a red point of light through the acrylic plate together with stars.
I designed a one-power aiming device shown in figure 1.
The case is made of 3mm thick plywood. The red LED is installed in a tube covered with a pinhole. The distance between the pinhole and the lens is adjustable with sliding the tube. After adjusting the focus on the acrylic plate, the tube is fixed on the case.
Figure 1. One-power Aiming Device
Material List
- Case
... 3mm thick plywood
... Tube with 7mm inner diameter (LED case)
- Optical parts
... Convex lens, focal length 40mm
- Acrylic Plate
- Electrical parts
... Red LED
... Battery x 2
... Battery case
... Switch
... Electric wire
- Others
... Black paint
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