How to change the lamp on SHADOWS

Procedure for changing the lamp on SHADOWS spectro-gonio radiometer:

1) If the lamp no longer starts when you press the "LAMP" button on the power supply, then you need to change the bulb. Check that the fan in the lamp housing is working. If it is not, the fan must be repaired/changed, otherwise there is a risk of overheating and the bulb’s life will be reduced.

2) Switch off the lamp power supply (black button in OFF position).

3) Unscrew the 4 black screws located around the removable plate of the casing containing the lamp (the removable face of the casing is the one to which the flux controller is connected). Be careful not to unscrew the two grey screws that control the position of the mirror. Once the screws have been removed, gently pull the plate outwards and place it on the optical table.

4) Put on gloves, pinch the base of the bulb and pull outwards to disconnect it. Be careful not to touch the mirror to the left of the bulb.

5) Still wearing gloves, plug in the new 250 W bulb, holding it firmly by its base. Push the bulb pins into the socket as far as they will go. Be careful not to touch the bulb or the mirror.

6) Replace and screw back the removable plate containing the lamp. Be careful not to touch the grey screws.

7) Check that the lamp feet are inside the two triangles marked by the strips of aluminum tape on the optical table.

8) Switch on the lamp power supply (black ON button) then press "LAMP" to switch on the lamp. Wait at least 45 min before starting a new measurement.

9) Run a Spectralon measurement (whole spectrum or one wavelength) and check that the flux value is relatively close to a previous measurement carried out under the same conditions (same slit opening, etc.).

10) If the flux value is of the same order of magnitude, well done! Record the date of the bulb change in the SHADOWS laboratory notebook.

11) If the flux is significantly different, then it is possible that the marking on the optical table has been degraded/modified or that the grey mirror screws have been touched. If this is the case, try to achieve a value close to the previous flux by repositioning the lamp in front of the monochromator entrance (rough alignment), then changing the position of the mirror with the grey screws. Once the maximum flux value has been reached, lock the position of the mirror using the screws located under the grey screws, and mark the position of the housing feet (two feet on the same diagonal) using tape.

Updated on 17 June 2023