Term
| A case hardened lense must be able to withstand |
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Definition
| A drop ball test with a 5/8" steel ball from a height of 50" |
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Term
| The weight of the ball, in ounces, used for a the drop ball test is |
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Definition
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Term
| For a thick edge lens, with a hand bevel, the bevel apex should be approximately how far back from the front surface |
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Definition
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Term
| The first step in the proper use of the vertometer is to |
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Definition
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Term
| A pattern has an A dimension of 52mm and a difference of 8mm. If you edge a lense to a 54mm eyesize, what is the B dimension |
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Definition
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Term
RX: -5.00 - -1.00 X 90. What is the tolerance for the axis
Also what is the power tolerance for the axis |
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Definition
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Term
| What are some disadvantages for heat tampering a lense |
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Definition
Warp lenses
Cracked & Chipped lenses
Loses safety effectiveness |
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Term
| What does toric curve (surface) mean |
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Definition
| Different readings on different axis |
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Term
| What is "effective diameter" |
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Definition
| 2 times the longest radius |
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Term
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Definition
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Term
| What is mechanical center |
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Definition
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Term
| In what dioptric range do most RX's fall into |
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Definition
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Term
| What is the size and weight of the ball used to test industrial thick lenses |
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Definition
| 1 inch diameter as well as 2.4 ounces |
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Term
| Name three lense types exempt from the drop-ball test |
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Definition
Exec bifocals
Raised ledge bifocals
Plastic lens
Plano sunglasses |
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Term
| What is the reason that a 6.00 D base curve was chosen as ideal |
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Definition
| Because it matches the curve of the rotation of the eye |
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Term
| What is the calibration of the lense clock between the black six and seven |
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Definition
Quarter steps
Quarter of a diopter |
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Term
| if you are using a zyl file correctly on a frame composed of zyl, what angle are you increasing |
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Definition
Let back angle
or
Temple spread |
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Term
| What is the state tolerance for vertical prism |
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Definition
+/- quarter for each eye
1/3 vertical prism |
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Term
| How much stronger are industrial safety frame then dress eyewear frames |
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Definition
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