GB/T 17341-1998[GB/T 17341-1998] Optics and optical instruments. Focimeters (English PDF)

5.1 Reference wavelength

The reference wavelength, which is used to display the vertex power and

Use a piece of white paper instead of the inspected lens, to adjust the focus of the eyepiece crosshairs clearly. Then remove the white paper. Focus the measurement target image of the instrument clearly.

7.2.1.2 Inspection of parallax-elimination

Adjust the focus of the crosshairs and the target image, according to 7.2.1.1.

Then it may check whether the parallax has been eliminated. The observer moves his gaze back and forth above the eyepiece; there shall be no obvious shift between the crosshairs and the target image.

7.2.2 Visually check whether the instrument meets the requirements of 6.5.

7.3 Inspection of vertex power indication

Use one group of spherical standard lens (it shall comply with the requirements of JJG 866-94), to check whether the indication error of vertex power meets the requirements of Table 1.

7.3.1 When the lens is not placed, the indication of vertex power of the instrument shall meet the requirements of 6.6.1.

7.3.2 Measure the spherical standard lenses one by one. The indication of

vertex power of the instrument shall meet the requirements of 6.6.2.

7.4 Inspection of indication of prismatic power

Use a set of prismatic standard lenses (it shall meet the requirements of JJG

866-94), to check whether the indication error of the prismatic power meets the requirements of Table 2.

7.4.1 When checking the prismatic power, it shall first make the vertex power of the instrument become zero.

7.4.2 Measure the prismatic standard lenses in sequence; the indication of

prismatic power of the instrument shall meet the requirements of 6.7.

7.5 Inspection of the deviation BETWEEN the axis mark of the optical center of the lens AND the optical axis of the focimeter

Use a +15D spherical standard lens (it shall comply with the requirements of

JJG 866-94). First align the center, so that the prismatic power is zero. Then mark the center axis's position. Then rotate the spherical standard lens by 180°.

Center it again. Mark the center axis's position again.

The half of the distance, between the axis marks of the center point, which are made for the first time and the second time, shall not be greater than 0.4 mm.

8.2.2 The items of the exit-factory inspection are 6.1 ~ 6.10 of this standard.

8.3 Type inspection

8.3.1 Type inspection shall be carried out in one of the following situations.

a) When the new product is subject to type-finalization identification, OR the old product is subject to prototype test after trans-plant production;

b) After normal production, if there are major changes in structure, material, process, which may affect product performance;

c) During normal production, inspections shall be carried out periodically or after accumulating a certain output;

d) When production resumes after a long-term suspension of production;

e) When there is a big difference BETWEEN the exit-factory inspection result

AND the last type inspection;

f) When the national quality supervision agency puts forward a requirement for type inspection.

8.3.2 The type inspection shall include all the items, which are specified in this standard. The samples for the type inspection shall be taken from the qualified products of the exit-factory inspection.

8.3.3 Sampling for type inspection. At least three samples shall be taken for each type of product; if one of the samples is unqualified, the product of this type shall be deemed unqualified.

9.1 Marking

9.1.1 Product mark

a) The name or trademark of the manufacturer;

b) Product name;

c) Product model;

d) Exit-factory number.

9.1.2 Packaging mark

The packaging mark of the instrument shall meet the requirements of GB/T

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